摘要:

Mendeleev Communications Electronic Version, Issue 5, 2001 1 Quantum-chemical simulation of the electronic structure and chemical bonding in the new ‘superstoichiometric’ titanium carbonitride Ti2CN4 Mikhail V. Ryzhkov* and Alexander L. Ivanovskii Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, 620219 Ekaterinburg, Russian Federation. Fax: +7 3432 74 4495; e-mail: ryzhkov@ihim.uran.ru 10.1070/MC2001v011n05ABEH001488 The electronic properties and the nature of interatomic interactions in the new ‘superstoichiometric’ metal-like titanium carbonitride Ti2CN4 with the spinel structure have been predicted using the ab initio DFT-DV calculaions of large clusters. Two classes of compounds provide the basis for the quest of novel ceramic and composite materials.The first class includes compounds of d metals (M) with light sp elements. Among them are cubic (B1-type) carbides and nitrides [M(C,N)]1 which (i) have wide homogeneity regions [containing a variable number of vacancies in the non-metallic sublattice M(C,N)y 0.5<y<1.0] and (ii) form mutual solid solutions. The properties of solid solutions (for example, carbonitrides MCxNy, x + y £ 1.0) change non-monotonically with concentration.1,2 It is important that atoms in these systems have an octahedral environment and the relative content of atomic components does not exceed (C,N)/M £ 1.0.The exception being several ‘superstoichiometric’ nitrides (MNy > 1 obtained as films) where the ratio N/M > 1.0 is achieved due to the presence of vacancies in the M sublattice.3 The second class comprises refractory compounds of sp nonmetals [carbides, nitrides and oxides of B, Si and Al, multicomponent phases, for instance, silicon oxynitrides (Si2N2O), sialons (Alx + ySi6 – xOxN8 – x + y), etc.4] characterised by a tetrahedral atomic coordination.Recently, the synthesis (at P = 15 GPa and T » 2000 K) of the new polymorphous modification of silicon nitride with the cubic structure (c-Si3N4) was reported.5 According to estimates,5 its cohesive properties are similar to those of the hardest modification of SiO2 (stishovite).The new c-Si3N4 phase is of the spinel structural type and contains silicon atoms in octahedral [SioN6] and tetrahedral [SitN4] surroundings (Sio:Sit = 2:1). By substituting C or Ti for silicon in c-Si3N4, the simulation of novel compounds, namely, the cubic carbon nitride (Co 2CtN4)6 and the ‘superstoichiometric’ titanium nitride (Tio 2 TitN4)7 was made. These hypothetical phases include 2/3 (Co) or 1/3 (Tit) cations in an octahedral or tetrahedral environment, which are not typical (in the corresponding binary phases C3N4 and TiN), i.e., the proposed6,7 compounds are difficult to synthesise.According to our opinion, it is more realistic to obtain a new cubic phase with the spinel structure, viz., the ‘superstoichiometric’ titanium carbonitride of the formal composition Ti2CN4, which will be isoelectronic and isostructural with c-Si3N4 and will contain C and Ti cations in inherent to them (in binary nitrides) octahedral [TioN6] and tetrahedral [CtN4] coordinations. It may be suggested that, assembled of the main ‘structural fragments’ TiN and C3N4, the ‘superstoichiometric’ carbonitride Ti2CN4 may possess an unusual combination of their most attractive properties: the plasticity of a metal-like titanium nitride1,2 and the hardness of a high-covalence carbon nitride.8 We performed a quantum-chemical simulation of the electronic structure and interatomic bonds in Ti2CN4 and compared them with those of the known nitrides TiN and C3N4.The electronic structure was calculated in the density functional theory (DFT) approximation using the original code of the self-consistent discrete variational (DV)8 cluster method with local exchange-correlation potential.9 The basis set of numerical atomic orbitals (AO), which were the solutions of Hartree–Fock–Slater equations for isolated neutral atoms, included Ti 4p functions in addition to occupied AOs.The Diophantine integration grid with 4000 and 2000 sample points per each Ti and C(N) site, respectively, was used for the calculations of matrix elements. Ti2CN4 was simulated by the 185-atomic cluster Ti28C29N128 (point group symmetry Td).It is known10 that the positions of atoms in the spinel structure (space group Fd3m–O7 h) are determined by two parameters a and x. Assuming that the parameters of the coordination polyhedra [TioN6] and [CtN4] for Ti2CN4 are equal to those for TiN (RTi–N = 2.122 Å) and C3N4 (RC–N = 1.585 Å), we derived the values a = 8.098 Å and x = 0.363. To compare the electronic structure of Ti2CN4 and C3N4 obtained using a similar Figure 1 Total (top) and partial densities of states for the Ti28C29N128 cluster. 100 80 60 40 20 0 20 0 10 0 80 60 40 20 0 20 0 20 0 20 0 20 0 –20 –15 –10 –5 0 5 10 15 20 E/eV Ti 3d Ti 4s Ti 4p Ti28C29N128 C 2p C 2s N 2p N 2s Table 1 Overlap populations (OP, e) of the valence orbitals of neighbouring atoms in TiN, Ti2CN4 and C3N4 (×103, per pair of interacting centres) and effective atomic charges (Qef, e) in TiN, Ti2CN4 and C3N4 (the charges obtained according to the Mulliken scheme are given in brackets).OP TiN Ti2CN4 C3N4 N 2s N 2p N 2s N 2p N 2s N 2p Ti(Co) 3d 4s (2s) 4p (2p) 33 –25 87 121 77 68 37 –1 53 174 73 48 — –7 79 — 130 229 Ct 2s 2p —— —— 14 173 205 349 –15 127 202 348 Qef [Ti (Co)] 1.43 (0.82) 1.49 (0.88) 0.57 (0.29) Qef (Ct) — 0.55 (0.36) 0.54 (0.34) Qef (N) –1.59 (–0.83) –0.93 (–0.53) –0.42 (–0.23)Mendeleev Communications Electronic Version, Issue 5, 2001 2 approach, we also performed DFT-DV calculations of the cluster Co 28Ct 29N128 in the C3N4 structure with bond lengths of 1.585 and 1.676 A for Ct.N and Co.N, respectively.6 Boundary conditions in the ¡®extended cluster¡� scheme11,12 were used.The model densities of states (MDOS) of the cluster Ti28C29N128 are presented in Figure 1. The total band width of bonding states is about 10 eV. It is made up of the contributions from hybrid Ti 3d.N 2p (0.5 eV), N 2p.C 2p (5.7.5 eV) and N 2p.C 2s orbitals [7.5.10 eV below the Fermi level (EF)] that form Ti.N and C.N bonds in [TioN6] and [CtN4] polyhedra.Ti2CN4 has no forbidden gap (FG) and will exhibit metal-like properties. A comparison with DFT-DV results for the cluster Ti79N140 used to model TiN13 shows that the most essential differences in the electronic structures of TiN and Ti2CN4 concern the mutual arrangement of the Ti 3d and N 2p states. In the nitride, the upper edge of the N 2p band (total width of 5 eV) is 4 eV below EF located in the region of ¥�-like antibonding Ti 3d states.13 The cubic C3N4 has a FG of more than 3 eV according to our calculations (1.14 eV according to ref. 7); its spectrum (Figure 2) contains a continuous N 2s,p.C 2s,p band of the total width of 17 eV. The differences in the MDOS of Ct centres in C3N4 and Ti2CN4 are attributed to the considerable broadening of Ct 2s,2p bands, their shift to lower binding energies and a decrease of Ct 2s,2p.N 2s hybridization in the nitride.The differences in the MDOS of Ct and Co in C3N4 concern the different hybridization effects in [CtN4] and [CoN6] polyhedra. The orbital overlap populations (OP) of TiN, C3N4 and Ti2CN4 obtained by the same cluster DFT-DV method are listed in Table 1.It can be seen that on going from TiN to Ti2CN4 the OP of Ti 3d.N 2p AO, which provides the major contribution to the Ti.N bonding, increase appreciably, whereas the OP of Ti 4p.N 2s and Ti 4p.N 2p AO decrease slightly. In general, the Ti.N chemical bonding in the simulated carbonitride is not weaker than that in TiN. A comparison of the OP of Ct centres with the neighbours in Ti2CN4 and C3N4 shows that the Ct.N bonds in the carbonitride are stronger due to the Ct 2p.N 2s hybridization.The fact that the octahedral coordination is less advantageous for carbon is evident from a comparisonthe OP of Ct.N and Co.N in C3N4: all the contributions forming the Co.N bonding are on the average 1.5 times smaller than those for Ct.N. Let us compare effective atomic charges (Qef) in TiN, Ti2CN4 and C3N4 (Table 1), which were obtained by three-dimensional integration in the space between nuclei.11 The values of Qef at Ti in TiN and Ti2CN4 appear to be similar, whereas the charges at nitrogen atoms in the carbonitride are only ¡í 60% of the corresponding values for TiN.The fundamental difference between Ti2CN4 and the known B1 carbonitrides MCxNy (x + y ¡Ì 1.0) incorporating carbon in the anionic state2 is the cationic form of Ct, the effective charges of Ct in Ti2CN4 and C3N4 being very close.The charges at N in C3N4 are half as large as in Ti2CN4 and are lower than those in TiN by a factor of 4, i.e., Ti2CN4 is intermediate in the degree of ionicity among the binary nitrides under consideration. In conclusion, note that due to the similarity of the simulated ¡®superstoichiometric¡� titanium nitride Ti2CN4 and the familiar interstitial phase TiN, Ti2CN4 may be expected to have properties2 typical of those of titanium nitride, such as nonstoichiometry in the N sublattice (Ti2CN4 .y-type compositions) or the formation of multicomponent solid solutions by replacing Ti atoms by other d metals (for example, Ti2 .xZrxCN4 and Ti2 . xHfxCN4). The synthesis of more complicated phases, where Si or Ge partially substitute for carbon, is possible. This work was supported by the Russian Foundation for Basic Research (grant no. 01-03-32513). References 1 L. Toth, Transition Metal Carbides and Nitrides, Academic Press, New York, 1971. 2 V. A. Gubanov, A. L. Ivanovskii and V. P.Zhukov, Electronic Structure of Refractory Carbides and Nitrides, University Press, Cambridge, 1994. 3 M. Lerch, E. Fuglein and J. Wrba, Z. Anorg. Allg. Chem., 1996, 622, 367. 4 A. L. Ivanovskii and G. P. Shveikin, Kvantovaya khimiya v materialovedenii. Nemetallicheskie tugoplavkie soedineniya i nemetallicheskaya keramika (Quantum Chemistry in Material Science. Refractory Compounds of Non-Metals and Non-Metal Ceramic), Izd.UB RAS, Ekaterinburg, 2000 (in Russian). 5 A. Zerr, G. Miehe, G. Serghiou, M. Schwarz, E. Kroke, R. Riedel, H. Fuess, P. Kroll and R. Boehler, Nature, 1999, 400, 340. 6 S.-D. Mo, L. Ouyang, W. Y. Ching, I. Tanaka, Y. Koyama and R. Riedel, Phys. Rev. Lett., 1999, 83, 5046. 7 W. Y. Ching, S.-D. Mo, L. Ouyang, T. Tanaka and M. Yoshiya, Phys. Rev., 2000, B61, 10609. 8 M. R. Press and D. E. Ellis, Phys. Rev., 1987, B35, 4438. 9 O. Gunnarsson and B. I. Lundqvist, Phys. Rev., 1976, B13, 4274. 10 U. L. Bragg and G. Klaringbull, Crystalline Structure of Minerals, Mir, Moscow, 1967 (in Russian). 11 M. V. Ryzhkov, Zh. Strukt. Khim., 1998, 39, 1134 [J. Struct. Chem. (Engl. Transl.), 1998, 39, 933]. 12 M. V. Ryzhkov, T. A. Denisova, V. G. Zubkov and L. G. Maksimova, Zh. Strukt. Khim., 2000, 41, 1123 [J. Struct. Chem. (Engl. Transl.), 2000, 41, 927]. 13 M. V. Ryzhkov and A. L. Ivanovskii, Zh. Strukt. Khim., 1999, 40, 630 [J. Struct. Chem. (Engl. Transl.), 1999, 40, 515]. 100 80 60 40 20 0 20 0 10 0 40 20 0 20 0 60 40 20 0 20 0 .20 .15 .10 .5 0 5 10 15 E/eV C29C28N128 Ct 2p Ct 2s Co 2p Co 2s N 2p N 2s Figure 2 Total (top) and partial densities of states for the Co 28 Ct 29 N128 cluster. Received: 26th June 2001; Com. 01/18

ISSN:0959-9436     

出版商:RSC    

年代:2001

数据来源: RSC

摘要:

Mendeleev Communications Electronic Version, Issue 5, 2001 1 New evidence for the electronic nature of the strong metal-support interaction effect over a Pt/TiO2 hydrogenation catalyst Aleksandr Yu. Stakheev,*a Yurii M. Shulga,b Natalia A. Gaidai,a Natalia S. Telegina,a Olga P. Tkachenko,a Leonid M. Kustova and Khabib M. Minacheva a N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.Fax: +7 095 135 5328; e-mail: st@ioc.ac.ru b Institute of Problems of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russian Federation 10.1070/MC2001v011n05ABEH001446 Analysis of the Pt 4f line asymmetry evidenced that the suppression of the hydrogenation activity of Pt/TiO2 in the SMSI state is caused by a decrease in the d-electron density at the Fermi level of platinum particles, while the net charge of the metal particles remains unaltered.Interest in the effect of strong metal-support interaction (SMSI) in M/TiO2 systems (M = Pt, Rh, Pd, Ni, etc.) has increased since 1980 because the performance of these catalysts can change dramatically depending on the reduction temperature.1 Despite intensive research efforts directed toward the elucidation of the nature of this phenomenon, its mechanism remains unclear.Several hypotheses have been proposed including encapsulation of metal particles by the support material or alteration of their electronic properties.2�C7 In this study, we used a new method for the evaluation of the electronic state of supported metal particles.This method is based on the analysis of the lineshape asymmetry in the XPS spectra of the metal.8 The importance of this parameter for studying the electronic state of supported metal clusters stems from the fact that the asymmetry of an XPS line is a function of the density of d-electrons at the Fermi level.9 Taking into account that d-electrons are deeply involved in the catalytic conversion over metals, an analysis of the XPS line asymmetry may provide a new insight into the relation between the electronic structure of supported metals and their catalytic performance.Therefore, the aim of this study was to find a relationship between variations in the catalytic activity and the electronic state of metal particles upon transition of the Pt/TiO2 catalyst between the SMSI and non-SMSI states.In order to minimise experimental uncertainties resulting from possible phase transitions in the carrier material and from variations in the dispersion of platinum, a 3 wt% Pt/TiO2 catalyst supported on high-purity rutile type TiO2 with a narrow particlesize distribution was used. The catalyst was prepared by impregnation of TiO2 (95 m2 g�C1) with an aqueous solution of H2PtCl6 (Aldrich, 99.995%) followed by drying and calcination at 500 ¡ãC.The removal of residual chlorine was monitored by XPS. After calcination, the catalyst samples were reduced in a hydrogen flow at 200 and 500 ¡ãC, and the particle size of platinum was estimated by transmission electron microscopy (EM- 125 electron microscope operated at 75 kV) and from X-ray diffraction line broadening.The X-ray diffraction line broadening gave a particle size of ~6.0 nm for both samples, which is in a good agreement with the estimates on the basis of XPS data (see below). The TEM data also ensured the absence of bigger platinum particles (>10 nm) in both samples. X-ray photoelectron spectra were obtained using an XSAM- 800 spectrometer (Kratos) with AlK¦Á1,2 radiation for spectra excitation.The binding energies of peaks were corrected with account of sample charging by referencing to the C 1s peak at 285.0 eV. The Pt/Ti surface atomic ratio was calculated from the integral intensities of XPS peaks using the Scofield photoionization cross-sections for AlK¦Á1,2 excitation.10 The particle size of Pt was calculated from the Pt 4f /Ti 2p intensity ratio using the Kerkof ¡®stacking sheets¡� model.11 Reductive and oxidative pretreatments were performed using a home-made reactor attached directly to the analytical chamber of the spectrometer.12 The samples were treated in flowing H2 and O2 and transferred to the spectrometer without exposure to ambient air.A Pt foil was cleaned using a standard procedure13 of several cycles of sputtering with Ar ions (2 kV, 0.25 ¦Ìa, t ~ 30 min) followed by heating in oxygen (pO2 = 6¡Á10�C5 mbar, t = 45 min).Surface contaminations were below the detection limits of XPS. The spectra were analysed by a curve fitting procedure using the Doniach�CSunjic function14 where e is the kinetic energy of the photoelectrons, G is the gamma-function, g is the lifetime width of the core hole created as a result of photoemission and a is the line asymmetry parameter. The function was convoluted with a Gaussian curve for taking into account an experimental broadening (instrumental resolution, sample inhomogeneity, etc.). Kinetic investigations of toluene hydrogenation activity under stationary conditions were carried out in a gradientless flow-cir- Table 1 Variations of the Pt 4f7/2/Ti 2p3/2 atomic ratio, Pt particle size, and binding energies (BE) of Pt 4f7/2 and Ti 2p3/2 lines with the reduction temperature.Pre-treatment Pt 4f7/2/Ti 2p3/2 intensity ratio Particle size of Pt/nma aCalculated from XPS data using the Kerkof model.5 Pt 4f7/2 BE/ eV Ti 2p3/2 BE/ eV H2, 200 ¡ãC 0.015 5.7 70.9 458.9 H2, 500 ¡ãC 0.013 6.5 70.8 458.9 O2, 200 ¡ãC + H2, 200 ¡ãC 0.013 6.5 70.8 458.8 H2, 300 ¡ãC 0.014 6.1 70.7 458.9 H2, 400 ¡ãC 0.013 6.5 70.8 458.9 H2, 500 ¡ãC 0.013 6.5 70.7 458.8 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 200 300 400 500 200 Reaction rate /mmol g�C1 cat h�C1 Reduction temperature/¡ãC Treatment in O2 at 200 ¡ãC Figure 1 Effect of the reduction temperature on the reaction rate of toluene hydrogenation at 130 ¡ãC over Pt/TiO2.I(e) = cos[0.5¦�a + q(e)], ~ G(1 �C a) (e2 + g2)(1 �C a)/2 q(e) = (1 + a)tan�C1(e/g), (1) (2)Mendeleev Communications Electronic Version, Issue 5, 2001 2 culation system at atmospheric pressure with the on-line gaschromatographic analysis of the reaction products. The reaction rates were measured at low conversions at 130 °C and PC7H8/ PH2 = 0.004.The dependence of the rate of toluene hydrogenation on the reduction temperature is depicted in Figure 1. The reaction rate abruptly decreases with increasing reduction temperature above 300–400 °C. However, the oxidation of the catalyst reduced at 500 °C in O2 at 200 °C followed by the reduction at 200 °C completely restores the activity.It was found that the oxidation–reduction cycles could be repeated five times without appreciable changes in the reaction rates. Clearly, the catalyst demonstrates the behaviour typical of reversible transition between non-SMSI and SMSI states. The XPS spectra of the Pt 4f line (Figure 2) indicated that the binding energy of the Pt 4f line in the catalyst reduced at 200 °C is higher by ~0.4 eV as compared to the position of the Pt 4f line of platinum foil, which is typical of supported metals.The curve fitting analysis of the line shape reveals a very similar value of the Pt 4f line asymmetry a for platinum foil and Pt/TiO2 reduced at 200 °C. The reduction at 500 °C does not affect the position of the Pt 4f line (Figure 2, Table 1). However, it leads to the pronounced narrowing of the line (Figure 2).Note that, after reduction at 500 °C, the Pt 4f line becomes narrower than that in Pt foil, which is unexpected for supported metal. The curve fitting analysis demonstrates that the narrowing resulted from a significant decrease in the asymmetry parameter a (Figure 2). The dependences of the catalytic activity (Figure 1) or the Pt 4f7/2 line asymmetry (Figure 3) on the reduction temperature reveals a good correlation between these parameters. An increase in the reduction temperature results in a simultaneous decrease in the catalytic activity and in er hand, the oxidation of the deactivated catalyst followed by the reduction at 200 °C completely restores the activity and the a value.The above data allowed us to interpret the observed effect. Two main mechanisms were proposed for the explanation of changes in the catalytic performance of the catalyst in the SMSI state. One mechanism implies the decoration or encapsulation of metal particles with the support material species. The other mechanism assumes the alteration of the electronic properties of the metal particles due to their interaction with defects on the support surface created in the course of high-temperature treatment.However, the Pt 4f/Ti 2p atomic ratio remained almost unchanged upon the treatments (Table 1). Therefore, we can presume that the decoration or encapsulation of the metal particles with the support moieties seems not to be the governing factor of the catalytic performance.The constancy of the Pt 4f/Ti 2p intensity ratio also implies the absence of any pronounced sintering of metal particles (Table 1). On the other hand, a decrease in the catalytic activity is consistent with the changes of the electronic state of the metal particles deduced from the variations of the Pt 4f line asymmetry. The decrease in the line asymmetry is presumably caused by a decrease in the local density of a d-state at the Fermi level.In turn, the structure of the d-band is the crucial factor determining the reactivity of metal surface.15,16 This allows us to suggest that the strong metal–support interaction can result in the lowering of the density of d-electrons on the Fermi level of the metal particle, thus decreasing the overall activity of the catalyst.It is noteworthy that the Pt 4f7/2 line asymmetry in the SMSI catalyst (a = 0.06) becomes close to that for Au (a = 0.03 for Au 4f7/2). The d-electron density of states for gold is low, which is in a good agreement with the low catalytic activity of Au in the reaction requiring the activation of H–H, C–H or C–C bonds. Thus, the results of this study indicate that the strong metal– support interaction induced by the high-temperature reduction presumably decreases the density of d-electrons at the Fermi level thus suppressing the activity of metal clusters.Another important finding is that the interaction between a metal particle and the support may affect the distribution of d-electrons in the metal cluster and change its catalytic performance, while the net charge of the particle remains nearly constant.This work was supported by the Russian Foundation for Basic Research (grant no. 99-03-32222). 500 °C, H2 200 °C, H2 Pt-foil 81 78 75 72 69 Binding energy/eV Figure 2 XPS spectra and the results of the curve-fitting analysis of the Pt 4f line in Pt/TiO2 after reduction at 200 and 500 °C and in Pt foil.Dotted lines correspond to the Pt 4f line with a = 0 and are shown for comparison. 0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 200 500 200 300 400 500 Reduction temperature/°C Asymmetry (a) of Pt 4f7/2 (a.u.) Figure 3 Dependence of the Pt 4f7/2 line asymmetry (a) on the reduction temperature. Treatment in O2 at 200 °C Pt-foilMendeleev Communications Electronic Version, Issue 5, 2001 3 References 1 S.J. Tauster, S. C. Fung and R. L. Garten, J. Am. Chem. Soc., 1978, 100, 170. 2 B. C. Bruce and P. N. Ross, J. Phys. Chem., 1986, 90, 6811. 3 D. E. Resasco, R. J. Fenoglio, M. P. Suarez and J. O. Cechini, J. Phys. Chem., 1986, 90, 4330. 4 T. H. Fleisch, A. T. Bell, J. R. Regalbuto, R. T. Thomson, G. S. Lane, E. E. Wolf and R. F. Hicks, Stud.Surf. Sci. Catal., 1988, 38, 791. 5 S. Tang, G. X. Xiong and H. G. Wang, J. Catal., 1988, 111, 136. 6 G. L. Haller and D. E. Resasco, Adv. Catal., 1989, 36, 173. 7 A. Dandekar and M. A. Vannice, J. Catal., 1999, 183, 344. 8 S.Hüfner, G. K. Wertheim and J. H. Wernick, Solid State Commun., 1975, 17, 417. 9 D. Briggs and J. C. Riviere, in Practical Surface Analysis by Auger and X-ray Photoelectron Spectroscopy, eds. D. Briggs and M. P. Seach, John Wiley, New York, 1983. 10 J. H. Scofield, J. Electron Spectrosc., 1976, 9, 29. 11 F. P. J. M. Kerkof and J. A. Moulijn, J. Phys. Chem., 1979, 83, 1612. 12 W. Grunert, A. Yu. Stakheev, E. S. Shpiro, K. Anders, R. Feldhaus, Kh. M. Minachev and W. Haupt, Reaktor-Schubstange System zur Hermetishen Uberfuhrung von Festkorperproben in Vakuumgerate, Patent no. 289596 BRD 02.05.91, 1–11. 13 Y. M. Sun, D. Sloan, D. J. Alberas, M. Kovar and J. M.White, Surf. Sci., 1994, 319, 34. 14 S. Doniach and M. Sunjic, J. Phys. C, 1970, 3, 285. 15 A. Ruban, B. Hammer, P. Stoltze, H. L. Skriver and J. K. Nørskov, J. Mol. Catal. A, 1997, 115, 421. 16 B. Hammer and J. K. Nørskov, Surf. Sci., 1995, 343, 211. Received: 1st March 2001; Com. 01/1772

ISSN:0959-9436     

出版商:RSC    

年代:2001

数据来源: RSC

摘要:

Mendeleev Communications Electronic Version, Issue 5, 2001 1 Chemiluminescence in the oxidation of europium ¥â-diketonates by dimethyldioxirane Dmitri V. Kazakov,* Gulchekhra Ya. Maistrenko, Olga A. Kotchneva, Ramilya R. Latypova and Valeri P. Kazakov Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, 450054 Ufa, Russian Federation. Fax: +7 3472 35 6066; e-mail: chemlum@ufanet.ru 10.1070/MC2001v011n05ABEH001482 The oxidation of Eu(FOD)3 and Eu(TTA)3 (FOD is heptafluorodimethyloctanedionate and TTA is thenoyltrifluoroacetonate) by dimethyldioxirane (DMD) is accompanied by chemiluminescence; the excitation of europium(III) occurs due to an energy released upon oxidation of the ligands.Luminescent lanthanide complexes are widely studied as structural and analytical luminescent probes and labels in various chemical and biochemical investigations.1,2 Another important feature of lanthanide chemistry is the utilization of these compounds as activators of chemiluminescence (CL) arising in chemical reactions,3.11 such as oxidation of organic compounds5 and decomposition of dioxetanes.1,6.10.Among the compounds of lanthanides, the complexes with organic ligands such as europium ¥â-diketonates, which exhibit intense fluorescence and high solubility in organic solvents, are useful for CL enhancement.A study of the CL of lanthanide chelates allows one to receive information on the mechanisms of various dark processes (e.g., quantum chain reactions) which otherwise are difficult or even impossible to explore.9,10 It is generally accepted that lanthanide ¥â-diketonates are inert activators, which are excited via intermolecular energy transfer from the excited species formed in a chemiluminescent reaction to the metal-centered 4f states. In this communication, we report a new type of lanthanide CL, when light emission arises due to the oxidation of organic ligands rather than as a result of outersphere energy transfer.We found that the interaction of Eu(FOD)3 with the powerful organic peroxide oxidant DMD12,13 is accompanied by bright CL. A study of the kinetics of CL¢Ó revealed that Eu(FOD)3 is not an energy acceptor, but chemically interacts with the dioxirane. In fact, regardless of the ratio between the reactants, the kinetics of CL decay has a rather complex character (Figure 1) and is characterised by the presence of two maxima (the first maximum, lasting 2.3 seconds and the second, which is considerably more prolonged and intense).Figure 1 shows that the total period of the CL decay coincides with the time of decrease of the dioxirane concentration (determined by iodometry in a control experiment) in the course of the reaction with Eu(FOD)3, and the consumption of DMD is stopped with the end of CL decay.Iodometric analysis revealed that, regardless of the excess (from 10 to 20 equivalents) of dioxirane over a lanthanide chelate, six equivalents of DMD is consumed in the reaction with one equivalent of Eu(FOD)3 so that two molecules of the dioxirane react with one molecule of the FOD ligand.The more excess of DMD over Eu(FOD)3 is taken in the reaction, the shorter time is needed to reach the main maximum in the kinetic curve of CL decay. The overall time of luminescence decay also decreases with increasing DMD concentration at a constant concentration of the europium complex. The emitter of CL is an excited EuIII ion since the CL spectrum recorded in the reaction of DMD with Eu(FOD)3 corresponds (Figure 2) to the photoluminescence spectrum of europium (570.650 nm).The yield of CL (20 ¡ÆC, acetone, [Eu(FOD)3]0 = = 1¡¿10.3 mol dm.1, [DMD]0 = 6¡¿10.3 mol dm.3) was calculated from the ratio of the total amount of light evolved in the reaction to the initial DMD concentration to be 6¡¿10.7 einstein mol.1. Unfortunately, it is impossible to calculate the europium excitation yield since the photoluminescence intensity considerably decreases during the reaction with DMD.The CL behaviour appeared to be sensitive to the presence of water. When the reaction was carried out in wet acetone, an almost threefold decrease in CL intensity was observed. This effect is expectable since H2O is known to quench the luminescence of lanthanides.However, the duration of CL decay is also significantly shortened (by a factor of 4.6) in the presence of water, indicating that the latter influences the chemical inter- ¢Ó CL was recorded using a FEU-140 photomultiplier on a photometric setup. In a typical procedure, a solution of Eu(FOD)3 in acetone was added to an acetone solution of DMD. The concentrations of reactants were varied in the ranges (5.100)¡¿10.4 mol dm.3 for Eu(FOD)3 and (1.25)¡¿10.3 mol dm.3 for DMD.The reactions were carried out at 20 ¡ÆC in a nitrogen atmosphere. DMD as an acetone solution was stored at .24 ¡ÆC over molecular sieves 4 A before use. Eu(FOD)3 was dehydrated according to the published method.14 The reactions were carried out in anhydrous acetone, which was obtained by boiling over K2CO3 for several hours followed by distillation from molecular sieves.In order to test the influence of water on the CL behaviour, in a control experiment, a small amount of twice distilled water was added to anhydrous acetone solutions of the reactants before the reaction so that the overall reaction volume contained ca. 1% H2O. The solvent effect on the CL behaviour was tested using dry co-solvents such as benzene, CCl4, MeCN, ethyl acetate, MeOH and tert-butanol added to acetone in a 12.5:1 ratio.EuIIIL3+ EuIIIP* Eu*IIIP hv (570.650 nm) O O C(Me)2 DMD L is heptafluorodimethyloctanedionate or thenoyltrifluoroacetonate P is the product of L oxidation by DMD Scheme 1 Excitation transfer 300 250 200 150 100 50 0 200 400 600 800 1000 15 14 12 11 10 9 8 7 6 Intensity (arbitrary units) t/s [DMD]/103 mol dm.3 1 2 20 10 0 0.0 2.5 5.0 Intensity (arbitrary units) t/s Figure 1 Kinetics of (1) CL decay and (2) consumption of DMD in the reaction with Eu(FOD)3 (acetone, 20 ¡ÆC, [Eu(FOD)3] = 1¡¿10.3 mol dm.3, [DMD] = 1.4¡¿10.2 mol dm.3, N2 atmosphere).Insert: the initial fast flash of CL intensity.Mendeleev Communications Electronic Version, Issue 5, 2001 2 action of the europium chelate with the dioxirane, presumably due to the ability of H2O to act as a donor of hydrogen bonds or possible coordination of water to the metal.In fact, solvents with hydrogen bond donor capacity, such as MeOH and tertbutanol, significantly accelerate the rate of CL decay as compared with acetone and MeCN.On the other hand, the solvent polarity is also important for this chemiluminescent reaction. Thus, the CL decays faster in weakly polar benzene or carbon tetrachloride compared with more polar acetone, acetonitrile and ethyl acetate. The europium complex is oxidised by DMD as follows from NMR and UV-spectroscopic data. The UV spectrum of the reaction product (acetone was evaporated from the system, and the residue was dissolved in CCl4) showed no intense absorption of Eu(FOD)3 at lmax = 290 nm, whereas a new weaker absorption band appeared at lmax = 420 nm.The 1H NMR spectrum [the residue was dissolved in a CDCl3.MeOH (2.5:1) mixture] showed a new signal at 3 ppm instead of that at 6 ppm attributed to the proton of the CH group14 (the signal of tert-butyl at 1.1 ppm remained unchanged).The photophysical characteristics of the reaction product are also completely different from those of the initial europium chelate. The new compound emits much less intense fluorescence upon irradiation with ultraviolet light at 390 nm: the photoluminescence spectrum taken after the reaction with DMD showed a drastic decrease in the photoluminescence intensity (PL-I) of europium (by more than two orders of magnitude), as compared with initial Eu(FOD)3.A redistribution of photoluminescence bands of europium is also observed (Figure 2). Similar results were obtained with the Eu(TTA)3 complex (TTA = thenoyltrifluoroacetonate). The CL emitter observed in the reaction of Eu(TTA)3 with DMD is an excited europium ion (570.650 nm), and the kinetics of luminescence decay is characterised by the presence of a maximum.Eu(TTA)3 is oxidised by DMD as manifested by the disappearance of its UV absorption at 343 nm in the course of the reaction. As in the case of Eu(FOD)3, six equivalents of DMD were consumed in the reaction with one equivalent of Eu(TTA)3, and the newly formed product of the chelate oxidation is more than two orders of magnitude weakly fluorescent compared with the initial europium complex.Although the precise mechanism of the reaction of DMD with Eu(FOD)3 or Eu(TTA)3 remains unknown, the data obtained allow us to conclude that the excitation of europium occurs as a result of its oxidation by the dioxirane.¢Ô The presence of a maximum in the kinetic curve of CL decay occurring upon the interaction of Eu(TTA)3 and Eu(FOD)3 with DMD is obviously caused by the accumulation of an intermediate (presumably of a peroxidic type) and its subsequent exothermic decomposition followed by energy transfer to the metal ion (Scheme 1).The results of this work also testify that the ¥â-diketonates of europium are not always passive and may significantly contribute to the production of CL as a result of their oxidation by peroxides.This circumstance should be taken into account when lanthanide complexes are used as ¡®inert¡� activators for studying chemi- or bioluminescent reactions. This work was supported by the Russian Foundation for Basic Research (grant no. 99-03-32140a), the programme Leading Scientific Schools Support (grant no. 00-15-97323) and the Presidium of the Russian Academy of Sciences (6th Young Scientists Projects Competition, grant no. 126). We thank Dr. S. S. Ostakhov and A. S. Alab¡�ev for their assistance in photoluminescence measurements. References 1 M. Elbanowski, B. Makowska, K. Staninski and M. Kaczmarek, J. Photochem. Photobiol. A: Chem., 2000, 130, 75. 2 I. Hemmila and S. Webb, Drug Discov.Today, 1997, 2, 373. 3 V. P. Kazakov, Zh. Fiz. Khim., 1965, 39, 2936 (Russ. J. Phys. Chem., 1965, 39, 1567). 4 V. P. Kazakov and A. I. Lapshin, Teor. Eksp. Khim., 1966, 2, 376 [Theor. Exp. Chem. (Engl. Transl.), 1966, 2, 286]. 5 V. A. Belyakov, R. F. Vasilev and G. F. Fedorova, Khim. Vys. Energ., 1978, 12, 247 [High Energy Chem. (Engl. Transl.), 1978, 12, 208]. 6 F. McCapra and D.Watmore, Tetrahedron Lett., 1982, 23, 5225. 7 A.V.Trofimov, R.F.Vasil¡�ev, K. Mielke and W. Adam, Photochem. Photobiol., 1995, 62, 35. 8 A. I. Voloshin, N. M. Shavaleev and V. P. Kazakov, J. Lumin., 2000, 91, 49. 9 V. P. Kazakov, A. I. Voloshin and S. S. Ostakhov, Kinet. Katal., 1999, 40, 1 [Kinet. Catal. (Engl. Transl.), 1999, 40, 180]. 10 V. P. Kazakov, A. I. Voloshin and N.M. Shavaleev, J. Photochem. Photobiol., A: Chem., 1998, 119, 177. 11 M. M. Richter and A. J. Bard, Anal. Chem., 1996, 68, 2641. 12 V. P. Kazakov, A. I. Voloshin and D. V. Kazakov, Usp. Khim., 1999, 68, 283 (Russ. Chem. Rev., 1999, 68, 253). 13 W. Adam, L. P. Hadjiarapoglou, R. Curci and R. Mello, in Organic Peroxides, ed. W. Ando, Wiley, New York, 1992, vol. 4, p. 195. 14 C. S. Springer, Jr., D.W. Meek and R. E. Sievers, Inorg. Chem., 1967, 6, 1105. 15 K. Sakanishi, Y. Kato, E. Mizukoshi and K. Shimizu, Tetrahedron Lett., 1994, 35, 4789. 16 D. V. Kazakov, A. B. Barzilova and V. P. Kazakov, Chem. Commun., 2001, 191. ¢Ô The results of this work give an example of the generation of excited states during the oxidative reactions of dioxiranes. The area of so-called oxidative CL of dioxiranes is a highly perspective avenue of their chemistry, which has begun to be explored only in recent years.13,15,16 1 2 (PL-I¡¿100) 3 550 600 650 l/nm 2 Figure 2 (1) Luminescence spectrum of Eu(FOD)3 (acetone, 20 ¡ÆC, [Eu(FOD)3]0 = 3¡¿10.3 mol dm.3). (2) Luminescence spectrum of the reaction mixture taken after the reaction of Eu(FOD)3 with DMD (acetone, 20 ¡ÆC, [Eu(FOD)3]0 = 3¡¿10.3 mol dm.3, [DMD]0 = 3¡¿10.2 mol dm.3). (3) Chemiluminescence spectrum taken during the reaction of DMD with Eu(FOD)3 (acetone, 50 ¡ÆC, [Eu(FOD)3]0 = 5¡¿10.3 mol dm.3, [DMD]0 = = 1.2¡¿10.2 mol dm.3, N2 atmosphere). Received: 7th June 2001; Com. 0

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 A theoretical study of the hydrogen molecule activation by the Ni2 cluster, nickel phthalocyanine and a complex formed by nickel phthalocyanine with the Ni2 cluster Viktor M. Mamaev,* Kirill V. Ermakov, Igor P. Gloriozov, Mikhail N. Gradoboev, Sergei Ya. Ishchenko and Dmitrii A. Lemenovskii Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation.Fax.: +7 095 932 8846; e-mail: vmam@nmr.chem.msu.su 10.1070/MC2001v011n05ABEH001473 A new system based on the addition of the Ni2 cluster to a mononuclear phthalocyanine complex with an energy stability of about 26 kcal mol.1 was suggested for the barrierless activation of the H.H bond. According to experimental data, mononuclear transition metal complexes in solutions1.3 and metal surfaces4,5 catalyse many reactions with the activation of H.H, C.H and C.C bonds.Catalytic systems can also be developed in the absence of solutions on the basis of isolated mononuclear phthalocyanine complexes of transition metals (MPc). The complexes can be immobilised on solid surfaces, and they are the most active catalysts for oxidation by molecular oxygen.6.8 The reactions of H.H and C.H bond activation by mononuclear transition metal complexes take place with considerable activation barriers, and the energy of products may be higher than the energy of isolated reactants.9.14 Transition metal clusters are more effective than mononuclear transition metal complexes.15,16 We theoretically found17(a) that catalysts based on binuclear palladium complexes are best suited for ethylene hydrogenation. In many cases, the processes of H.H bond activation by transition metal clusters in a gas phase are barrierless,16,17(b),18 as distinct from the activation by mononuclear complexes.However, in contrast to metal complexes, clusters are unstable in a gas phase; they are produced by the action of powerful radiation on a metal surface before an activation process.16 Based on a theoretical study, we found that the Ni2 clusters can be stabilised by the addition to the MPc=NiPc molecule with the formation of bonds with peripheral atoms of the macrocyclic ring: We also found that Ni.Ni does not form a metal.metal bond with the Ni(1) atom of the Ni(1)Pc complex: We examined the reactions of H.H bond activation by the NiPc molecule, the Ni.Ni cluster and the Ni(1)Pc(Ni.Ni) complex: We found that reactions (IV) and (V) are barrierless.The calculations were performed using the density functional theory (DFT), which was successfully applied to metal complexes such as metal porphyrins.19.22 The published computer program23 and the exchange correlation functional PBE22 were used.Large orbital basis sets of contracted Gaussian-type functions of the size (5s1p)/[3s1p] for H, (11s6p2d)/[6s3p2d] for C, N and (18s13p8d)/[12s9p4d] for Ni were used in conjunction with the density-fitting basis sets of uncontracted Gaussian-type functions of the size (5s1p) for H, (10s3p3d1f) for C, N and (18s6p6d5f 5g) for Ni. The basis set was optimised by D.N. Laikov.23 Based on the full optimisation of molecular systems, we examined the geometry of the products [PR(i), i = I, II], as well as the energy difference between PR and separated reactants (SR) .E(i) = E[PR(i)] . E[SR(i)], for reactions (I) and (II). According to the molecular geometry of PR(I) = Ni(1)Pc(Ni.Ni), the Ni.Ni cluster occurs at a considerable distance from Ni(1), which is longer than 4.5 A, and forms bonds with the peripheral atoms of Ni(1)Pc [see Figure 1(a) and Table 1].The obtained value .E(I) = .26.6 kcal mol.1 is indicative of the stabilisation of the Ni.Ni cluster. Qualitatively, the addition of the second cluster to Ni(1). Pc(Ni.Ni) [reaction (II)] is analogous to reaction (I) [see Figure C(30) Ni(2) C(3) Ni(3) N(8) N Ni(1) N N N N N N N (a) (b) N N(8) N Ni(2) Ni(3) Ni(1) Figure 1 The numbering of atoms in the molecules (a) PR(I) and (b) PR(II) of the products of reactions (I) and (II).Ni(4) Ni(5) N N N N N(6) C(12) C(22) C(30) C(3) Ni(1)Pc + (Ni.Ni) ¢ç Ni(1)Pc(Ni.Ni) Ni(1)Pc(Ni.Ni) + (Ni-Ni) ¢ç Ni(1)Pc[2(Ni.Ni)] (I) (II) Ni(1)Pc + (Ni.Ni) ¢ç [Ni.Ni(1).Ni]Pc ¢ç Ni(1)Pc(Ni.Ni) (Ia) NiPc + H2 ¢ç (H.Ni.H)Pc (Ni.Ni) + H2 ¢ç H.(Ni.Ni).H Ni(1)Pc(Ni.Ni) + H2 ¢ç Ni(1)Pc[H.(Ni.Ni).H] (III) (IV) (V) Table 1 Atomic distances in the products of reactions (I) and (II)/A.Distancea aThe numbering of atoms is shown in Figure 1. PR(I) PR(II) R[Ni(2).Ni(3)] 2.45 2.40 R[Ni(2).C(3)] 1.99 2.01 R[Ni(2).C(30)] 2.01 1.93 R[Ni(3).N(8)] 1.92 1.89 R[Ni(4).Ni(5)] 0 2.44 R[Ni(4).C(12)] 0 1.99 R[Ni(4).C(22)] 0 2.01 R[Ni(5).N(6)] 0 1.92Mendeleev Communications Electronic Version, Issue 5, 2001 2 1(b) and Table 1].In this case, .E(II) = .25.5 kcal mol.1, which is close to .E(I). The [Ni.Ni(1).Ni]Pc complex was examined because we assumed that the Ni.Ni cluster could be stabilised by the formation of metal.metal bonds with the Ni(1) atom of the Ni(1)Pc complex [reaction (Ia)].The DFT optimisation of the Ni(1)Pc complex suggested that the Ni(1) atom has four bonds with four nitrogen atoms with the same lengths R[Ni(1).N] = 1.91 A. To form metal.metal bonds at the Ni(1) atom, the Ni.Ni cluster was oriented with the bond lengths R[Ni(1).Ni] = 2.3 A, which are close to R(Ni.Ni) in the Ni.Ni cluster (see Figure 2). In the [Ni.Ni(1).Ni]Pc complex thus obtained the closest distances are R(Ni.N) ¡í 2.5 A, which are much longer than R[Ni(1).N] = 1.91 A.The structure of the [Ni.Ni(1).Ni]Pc complex changed after the optimisation. The internuclear distances Ni.Ni(1) increased from 2.3 to 2.5 and 2.7 A. At the same time, the Ni.N bonds 1.9 A long were formed. Thus, the [Ni.Ni(1).Ni]Pc complex was converted into the PR(Ia) = Ni(1)Pc(Ni.Ni) complex.In the PR(Ia) complex, the Ni.Ni cluster is closer to Ni(1) than in the PR(I) complex. In this case, the energy difference .E(Ia) was .14.6 kcal mol.1, which is 12 kcal mol.1 higher than .E(I). Thus, the Ni.Ni cluster on Ni(1)Pc becomes more stable by the formation of Ni.N and Ni.C bonds at the longest Ni.Ni distances from Ni(1). To study the reaction of H.H bond activation by the NiPc complex [reaction (III)], we optimised (H.Ni.H)Pc with different fixed R(H.H).Figure 3 summarises the results. It can be seen that NiPc cannot activate the H.H bond of the hydrogen molecule. The optimisation of the (H.Ni.H)Pc complex with no fixed R(H.H) resulted in the separated reactants NiPc + H2. To examine the reaction path (RC) of H.H bond activation in the hydrogen molecule by the Ni.Ni cluster [reaction (IV)], we optimised H.(Ni.Ni).H with different fixed R(H.H).The rhombic orientation between H.H and Ni.Ni was retained over the entire path; this is consistent with the results of a study on the barrierless activation of the H.H bond by the Pd.Pd complex.18 Figures 2 and 4 illustrate the results. Evidently, the H.H bond activation by the Ni.Ni cluster is barrierless and .E(III) = = .46.44 kcal mol.1 (with respect to the singlet state of Ni.Ni).To examine the H.H bond activation in the hydrogen molecule by the Ni(1)Pc(Ni.Ni) complex [reaction (V)], we optimised the structure of Ni(1)Pc[Ni(H.H)Ni] with different fixed R(H.H). We found that the H2 molecule can be activated by the Ni(1)Pc(Ni.Ni) complex (Figure 4), and this activation is barrierless, as well as the activation of H.H bonds by clusters in a gas phase.In the activation of the H2 molecule by the Ni(1)Pc(Ni.Ni) complex [PR(V)] the bond lengths R(Ni.N) and R(Ni.C) of the Ni.Ni cluster with NiPc atoms insignificantly increased by ~0.1 A (Tables 1 and 2). The bond lengths R(H.Ni) of hydrogen atoms of the activated H2 molecule with the Ni.Ni cluster atoms on the surface of NiPc are ~1.6 A.They are insignificantly different from the corresponding bond lengths of the reaction product in the activation of the hydrogen molecule by isolated Ni.Ni clusters (Figure 2, Table 2). The stabilisation energy is .E(V) = .35.5 kcal mol.1; thus, the product of hydrogen molecule activation by the Ni(1)Pc(Ni.Ni) complex is more stable than that in the activation by mononuclear complexes.9,12,14,24 Thus, effective catalytic systems can be developed on the basis of isolated Ni(1)Pc molecules with transition metal clusters.References 1 S. B. Duckett, R. Eisenberg and A. S. Goldman, J. Chem. Soc., Chem. Commun., 1993, 1185. 2 X-X. Zhang and B. B. Wayland, J. Am. Chem. Soc., 1994, 116, 7897. 3 R. H. Schultz, A. A. Bengali, M. J. Tauber, B. H.Weiller, E. P.Wasserman, K. R. Kyle, C. B. Moore and R. G. Bergman, J. Am. Chem. Soc., 1994, 116, 7369. 4 A. D. Johnson, S. P. Daley, A. L. Utz and S. T. Ceyer, Science, 1992, 257, 223. 5 S. T. Ceyer, Science, 1990, 239, 133. 6 S. A. Borisenkova, Neftekhimiya, 1991, 31, 391 (in Russian). 7 B. V. Romanovskii, Kinet. Katal., 1999, 40, 742 [Kinet.Catal. (Engl. Transl.), 1999, 40, 673]. 8 (a) S. A. Borisenkova, Vestn. Mosk. Univ., Ser. 2: Khim., 1984, 75, 427 (in Russian); (b) S. A. Borisenkova, E. G. Girenko and B. G. Giherassinov, Journal of Porphyrins and Phtalocyanines, 1999, 3, 210. 9 N. Koga and K. Morokuma, Chem. Rev., 1991, 91, 823. 10 K. Albert, Ph. Gisdakis and N. Rosch, Organometallics, 1998, 17, 1608. 11 Sh. Sakaki, B. Biswas and M. Sugimoto, Organometallics, 1998, 17, 1278. Table 2 Atomic distances in the product of reaction (V)/A. Distance PR(V) R[Ni(2).Ni(3)] 2.35 R[Ni(2).C(3)] 2.11 R[Ni(2).C(30)] 2.08 R[Ni(3).N(8)] 2.03 R[Ni(2).H(17)] 1.62 R[Ni(2).H(18)] 1.57 R[Ni(3).H(17)] 1.64 R[Ni(3).H(18)] 1.61 R[H(17).H(18)] 1.81 H Ni H Ni 1.58 2.30 1.58 1.58 1.58 Figure 2 The structure of the product of reaction (IV) (bond lengths in angstrom units). 120 100 80 60 40 20 0 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 E/kcal mol.1 R(H.H)/A Figure 3 The energy profile constructed on the basis of the optimisation of (H.Ni.H)Pc with different fixed R(H.H): E is the energy difference E[(H.Ni.H)Pc] .E[SR(1a)]. .5 0 5 .10 .15 .20 .25 .30 .40 .35 .45 .50 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 E/kcal mol.1 R(H.H)/A V IV Figure 4 The reaction profiles for H.H bond activation in hydrogen molecules by (IV) the Ni.Ni cluster and (V) the Ni(1)Pc(Ni.Ni) complex: R(H.H) (A) is the reaction coordinate.Mendeleev Communications Electronic Version, Issue 5, 2001 3 12 V.M. Mamaev, I. P. Gloriozov, V. V. Simonyan, E. V. Zernova, E. M. Myshakin and Yu.V. Babin, Mendeleev Commun., 2000, 12. 13 V. M. Mamaev, I. P. Gloriozov, V. V. Simonyan, Yu. V. Babin and D. A. Lemenovskii, Mendeleev Commun., 2000, 155. 14 Yu. A. Ustynyuk, L. J. Ustynyuk, D. N. Laikov and V. V. Lunin, J. Organomet. Chem., 2000, 597, 182. 15 J. J. Carroll, K. L. Haug, J. C.Weisshaar, M. Blomberg, P. Siegbahn and M. Svensson, J. Phys. Chem., 1995, 99, 13955. 16 P. Fayet, A. Kaldor and D. M. Cox, J. Chem. Phys., 1990, 92, 254. 17 (a) V. M. Mamaev, I. P. Gloriozov, D. A. Lemenovskii and Yu. V. Babin, Mendeleev Commun., 2000, 51; (b) V. M. Mamaev, I. P. Gloriozov, V. V. Simonyan, E. V. Zernova, A. V. Prisyajnyuk and Yu. A. Ustynyuk, Mendeleev Commun., 1997, 246. 18 M. R. A. Blomberg, P. E. M. Siegbahn and M. Svensson, J. Phys. Chem., 1992, 96, 5783. 19 V. M. Mamaev, I. P. Gloriozov, D. A. Lemenovskii and E. V. Zernova, Kinet. Katal., 2000, 41, 40 [Kinet. Catal. (Engl. Transl.), 2000, 41, 33]. 20 N. Matsuzava, M. Ata and D. A. Dixon, J. Phys. Chem., 1995, 99, 7698. 21 C. Rovira, K. Kunc, J. Hutter, P. Ballone and M. Parrinello, J. Phys. Chem., 1997, 101, 8914. 22 J. P. Perdew, K. Burke and M. Ernzerhof, Phys. Rev. Lett., 1996, 77, 3865. 23 D. N. Laikov, Chem. Phys. Lett., 1997, 281, 151. 24 F. Maseras, A. Liedos, E. Clot and O. Eisenstein, Chem. Rev., 2000, 100, 601. Received: 7th May 2001; Com. 01/1799

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 Water-soluble [60]fullerene compositions with carbohydrates Larissa S. Litvinova,* Veniamin G. Ivanov, Maxim V. Mokeev and Vladimir N. Zgonnik Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg, Russian Federation. Fax: +7 812 328 6869; e-mail: LitvinLS@hq.macro.ru 10.1070/MC2001v011n05ABEH001459 Water-soluble compositions of [60]fullerene with carbohydrates were mechanochemically synthesised and investigated by UV-VIS and solid-state high-resolution 13C NMR spectroscopy.For using fullerenes in biology and medicine, they should be converted into a water-soluble state by means of complexing agents. At present, several water-soluble fullerene-containing compounds have been obtained.These are [60]fullerene complexes with ¦Ã-cyclodextrin,1,2 polyvinylpyrrolidone3,4 water-soluble calix[n]- arenes,5,6 poly(vinyl alcohol)7 and tetraphenylporphine with polyvinylpyrrolidone. 8 Moreover, the preparation of stable colloid aqueous solutions of [60]fullerene with no stabilizing agents has also been described.9,10 However, no information is available on the products of fullerene interaction with low- and high molecular weight carbohydrates such as dextran, which is known in medicine as an effective blood plasma substitute. The probable reason is the absence of common solvents for fullerene and carbohydrates, making it possible to mix the components homogeneously and to investigate the products of their interaction.The aim of this work was to obtain water-soluble [60]fullerene compositions with oligosaccharides and polysaccharides (dextran with a molecular weight of 40 kDa), to study the state of fullerene, and to find optimal conditions for the formation of a water-soluble product with carbohydrates characterised by different molecular weights.To obtain fullerene compositions with carbohydrates, a modified mechanochemical method7 was used.A carbohydrate was suspended in a fixed volume of [60]fullerene solution in CCl4 at a concentration of 0.1 mg ml�C1. After evaporating the solvent in air, the mixture was ground in an agate mortar and then dried in a vacuum at 40 ¡ãC for 48 h to remove CCl4 traces. The [60]fullerene content of the dry mixture with the carbohydrate ranged from 0.1 to 30%.A known volume of water was added to the finally dispersed powder; the mixture was stirred for 1 min and centrifuged; then, the solution was separated from the precipitate by decantation. The water-soluble part of the composition was investigated by UV-VIS spectroscopy on a Specord M40 spectrophotometer. High resolution solid-state 13C NMR spectra were obtained at room temperature on a Bruker CPX-100 spectrometer using magic angle spinning (MAS), and cross-polarisation (CP MAS) techniques. The working frequency of 13CNMR was 25.18MHz, and the sample spin rate was 3�C4 kHz.Tetramethylsilane (TMS) was used as reference. The concentration and the molar absorption coefficient of water-soluble [60]fullerene were determined photometrically by isolating fullerene from aqueous solutions by TLC on silica gel plates prewashed with MeOH using CHCl3 as an eluent.Under these conditions, carbohydrate complexes were decomposed and the fullerene remained entirely at the solvent front. Subsequently, the part of the silica gel layer containing fullerene was transported to a Schott filter, [60]fullerene was desorbed from silica gel wih CCl4, the solution obtained was photometrically examined at l = 328 nm.The concentration (C) and molar absorption coefficient (e) of fullerene passed into water were determined. The RSD for C and e was better than 15%. Figure 1 shows the electronic spectra of a [60]fullerene solution in hexane, the spectra of its films on a quartz support and the spectra of an aqueous solution of a [60]fullerene composition with sucrose.The spectra of the composition and the film are similar and greatly differ from that of fullerene. The bands are wider, the bathochromic shifts of band maxima is observed, the ratio of their intensities change and new spectral features in the long-wave region appear. A similar bathochromic shift and band widening in the spectra of solutions of the products of [60]fullerene interaction with ¦Ã-cyclodextrin and liposomes was attributed previously8 to the presence of [60]fullerene aggregates in solutions.Similar results were obtained for [60]fullerene�C pyridine�Cwater mixtures,9 which were explained by the formation of monodisperse, spherical, and chemically inert [60]fullerene nanocapsules. The absorbance of solutions depends on the fullerene content of the initial composition (Figure 2). The solutions obtained from a composition with a high fullerene content (10% or higher) and, correspondingly, with a lower carbohydrate content, are characterised by low absorbance.This is probably due to a low concentration of fullerene passed into solution (for sucrose, less than 1¡Á10�C5 mol dm�C3). The increasing carbohydrate fraction in the composition at a fixed quantity of [60]fullerene leads, first, to a drastic and then to a gradual increase in absorbance. When the sucrose content of the solid-phase composition is higher than 99.7 wt%, the fullerene concentration in water increases A 1.0 0.8 0.6 0.4 0.2 210 250 300 400 500 600 1 2 3 ¡Á0.5 ¡Á2.5 Figure 1 Absorption spectra of (1) a [60]fullerene solution in hexane (2) a [60]fullerene film on quartz and (3) an aqueous solution of sucrose�C[60]fullerene composition (solid-phase [60]fullerene concentration is 2 wt%).l/nm A 0.8 0.6 0.4 0.2 0.125 0.25 0.5 1 2 4 8 16 32 [60]Fullerene/Carbohydrate (wt%) 1 2 Figure 2 Absorbance (330 nm) of [60]fullerene in an aqueous solution as a function of [60]fullerene concentration in solid-phase compositions with (1) sucrose and (2) dextran (40 kDa).Mendeleev Communications Electronic Version, Issue 5, 2001 2 up to (1.2)¡¿10.4 mol dm.3.The absorbance and hence concentration are lower for dextrans than for sucrose. To better understand the properties of the products, the concentration dependence of the molar absorption coefficient of water-soluble fullerene was studied using the above technique (Figure 3).The molar absorption coefficient increases with decreasing the concentration of fullerene passed into water. This indicates that the ratio of components passed into solution from the compositions with different carbohydrate contents is not constant. A maximal concentration of fullerene in water at its concentration of 4% in the solid-phase composition was attained with the use of sucrose, and it was 5¡¿10.4 mol dm.3. The concentration dependence of absorption, the UV-VIS spectra of water-soluble fractions (broadening and shift of fullerene bands in the UV region and new spectral features in the long-wave range) show that fullerene passes into water as aggregates.They exhibit high stability and do not form smaller fragments when the solution is diluted.It is impossible to extract fullerene from aqueous solutions by organic solvents. The solid-state 13C MAS NMR spectrum of a composition with dextran contains a signal characteristic of [60]fullerene (143.6 ppm). The half-width of the line increased to 1.2 ppm, whereas for pure fullerene it is 0.16 ppm. The spectrum of the same composition obtained by a CP MAS technique also contains a [60]fullerene signal, which indicates that protoncontaining groups are located near the fullerene surface.In the spectra of the composition with sucrose, the [60]fullerene line in the MAS spectrum is broadened (1.2 ppm) and shifted upfield (dMAS 141.3 ppm). Moreover, in the CP MAS spectrum, a new low-intensity peak appeared at the higher magnetic field (dCP MAS 139.2 ppm).The line splitting and upfield shift of the [60]fullerene signal in CP MAS can be interpreted by the interaction of fullerene with hydroxyl groups in the carbohydrate. This suggestion is consistent with published data,2 according to which the interaction in the [60]fullerene complex with ¥ã-cyclodextrine takes place via oxygen atoms including tyl groups. This interaction is of the donor.acceptor character.2 It was found13,14 that when [60]fullerene is included in capsule-like cage molecules (palladium-linked bis-porphyrins and homooxacalix[3]arene dimeric capsules) the 13C NMR spectra also exhibit an additional upfield line of encapsulated [60]fullerene.The NMR data confirm the fullerene interaction with the carbohydrate in the composite. In conclusion, water-soluble compositions of [60]fullerene with sucrose and dextran (40 kDa) were prepared mechanochemically.Sucrose is a better solubilising agent for [60]fullerene than dextran. Two types of interactions occurred in the test samples: fullerene .carbohydrate (complexation) and fullerene.fullerene (aggregation).The stability of an aqueous solution of fullerene with respect to [60]fullerene extraction by such solvents as toluene and chloroform suggests that fullerene passes into solution in the form of aggregates in a carbohydrate shell. Moreover, the surface carbohydrate layer forms a van der Waals complex with fullerene. This work was supported by the Russian Research and Development Programme ¡®Fullerenes and Atomic Clusters¡� (grant no. 94053). References 1 T. Andersson, K. Nilsson, M. Sundahl, G.Westman and O.Wennerstrom, J. Chem. Soc., Chem. Commun., 1992, 604. 2 Z. Yoshida, H. Takekuma, S. Takekuma and Y. Matsubara, Angew. Chem., Int. Ed. Engl., 1994, 33, 1597. 3 Y. N. Yamakoshi, T. Yagami, K. Fukuhara, S. Sueyoshi and N. Miyata, J. Chem. Soc., Chem. Commun., 1994, 517. 4 L. V. Vinogradova, E. Yu. Melenevskaya, A. S. Khachaturov, E. E. Kever, L. S. Litvinova, A. V. Novokreshchenova, M. A. Sushko, S. I. Klenin and V. N. Zgonnik, Vysokomol. Soedin., Ser. A, 1998, 40, 1854 (Polym. Sci., Ser. A, 1998, 40, 1152). 5 J. L. Atwood, G. A. Koutsantonis and C. L. Raston, Nature, 1994, 368, 229. 6 K. Komatsu, K. Fujiwara, Y. Murata and T. Braun, J.Chem. Soc., Perkin Trans. 1, 1999, 2963. 7 L. S. Litvinova and V. N. Zgonnik, Abstracts of IWFAC¡�99, St. Petersburg, 1999, p. 294. 8 E. Yu. Melenevskaya, V. A. Reznikov, L. S. Litvinova, L. V. Vinogradova and V. N. Zgonnik, Vysokomol. Soedin., Ser. A, 1999, 41, 864 (Polym. Sci., Ser. A, 1999, 41, 578). 9 G. V. Andrievsky, M. V. Kosevich, O. M. Vovk, V. S. Shelkovsky and L.A. Vashchenko, J. Chem. Soc., Chem. Commun., 1995, 1281. 10 N. O. Mchedlov-Petrossyan, V. K. Klochkov and G. V. Andrievsky, J. Chem. Soc., Faraday Trans., 1997, 93, 4343. 11 R. V. Bensasson, E. Bienvenue, M. Dellinger, S. Leach and P. Seta, J. Phys. Chem., 1994, 98, 3492. 12 A. Mrzel, A. Mertelj, A. Omerzu, M. opi and D. Mihailovic, J. Phys. Chem. B, 1999, 103, 11256. 13 D. Sun, F. S. Tham, C. A. Reed, L. Chaker, M. Burgess and P. D. W. Boyd, J. Am. Chem. Soc., 2000, 122, 10704. 14 A. Ikeda, M. Yoshimura, H. Udzu, C. Fukuhara and S. Shinkai, J. Am. Chem. Soc., 1999, 121, 4296. 4 3 2 1 0.0 0.4 0.8 1.2 1.6 [C60]/104 mol dm.3 e/10.4 dm3 mol.1 cm.1 Figure 3 The concentration dependence of the molar absorption coefficient (e) of water-soluble fullerene in aqueous solutions of a [60]fullerene. sucrose composition (l = 440 nm). (a) (b) (c) 0.16 1.2 165 155 145 135 125 160 150 140 130 120 Figure 4 High-resolution solid-state 13C NMR spectra of (a) [60]fullerene, (b) and (c) sucrose.[60]fullerene composition (20 wt%) in MAS (a), (b) and CP MAS (c) modes. d/ppm C c Received: 3rd April 2001; Com. 01/

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 Molecular structure of 1,3-dihydroxydecamethylcyclohexasilane Alexander A. Korlyukov, Denis Yu. Larkin, Nina A. Chernyavskaya,* Mikhail Yu. Antipin and Alexey I. Chernyavskii A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow, Russian Federation. Fax: +7 095 135 5085; e-mail: chern@ineos.ac.ru 10.1070/MC2001v011n05ABEH001484 As found by X-ray diffraction analysis, oxygen atoms in the molecule of 1,3-dihydroxydecamethylcyclohexasilane occupy axial positions.Bifunctional cyclosilanes are valuable starting compounds for the synthesis of polycyclic silanes and cyclolinear copolymers containing cyclosilane units. It was found earlier1,2 that the interaction of dodecamethylcyclohexasilane (Me2Si)6 with SbCl5 in a CCl4 solution yields dichloro-substituted cyclohexasilanes, which are a mixture (in a ratio of ~1:1) of structural isomers, 1,3-dichlorocyclohexasilane 1 and 1,4-dichlorocyclohexasilane 2. These isomers should be separated for their use as starting compounds for the synthesis of polymers or copolymers.Structural isomers 1 and 2 have similar physico-chemical properties; therefore, they can be separated by only chemical methods.2.4 The simplest method is the hydrolysis of an isomeric mixture of 1 and 2 followed by the separation of reaction products 3 and 4 by vacuum distillation (Scheme 1).4 The treatment of hydrolysis products 3 and 4 with acetyl chloride leads to dichloro-substituted cyclosilanes 1 and 2 in quantitative yields. The X-ray diffraction analysis of the hydrolysis products of compound 2 demonstrated4 that a unit cell contains both bridged compound 4 and 1,4-dihydroxycyclosilane 5 in a ratio of 2:1.The X-ray data for compound 3 were not reported. We reproduced the method4 of separation of hydrolysis products by vacuum distillation, but dihydroxy derivative 3 was obtained in a low yield (< 10%), probably, due to its condensation during distillation.We obtained compound 3 in 48% yield by partial crystallization of hydrolysis products.¢Ó We determined the molecular and crystal structure of 3 by X-ray diffraction analysis.¢Ô The six-membered cyclosilane ring exhibits a chair conformation (Figure 1). The oxygen atoms O(1) and O(2) occupy axial positions.The positions of the oxygen atoms O(1) and O(2) may be described as cis; the corresponding pseudotorsion angle O(1)Si(1)Si(3)O(2) is equal to .8.0¡Æ. It is noteworthy that, in the molecule of 5, similar oxygen atoms occupied the trans positions.4 The bond lengths and bond angles are close to those in the majority of similar compounds.5 The Si(4).Si(5) and Si(5).Si(6) bonds in 3 are shorter than others.The elongation of the other Si.Si bonds may be explained by an anomeric effect (n.¥ò* interaction between oxygen lone pairs and vacant orbitals of the Si.Si bonds). The disordering of the ¢Ó 12.0 g (0.034 mol) of an isomeric mixture of 1 and 2 in 100 ml of pentane, which was obtained by the interaction of 20.0 g (0.052 mol) of (Me2Si)6 with 23.6 g (0.079 mol) SbCl5, was added dropwise to a mixture of 40 ml (0.45 mol) of H2O and 15.8 g (0.157 mol) Et3N in 100 ml of pentane. The precipitate of Et3N¡�HCl was filtered off.The organic solvent and an excess of Et3N and H2O were removed in vacuo at room temperature. Compound 3 was obtained by partial crystallization of the residue from pentane. Yield 2.6 g (48% on a 1 basis), mp 124.126 ¡ÆC.MS, m/z (%): 334 (11.9) [M . H2O]+, 319 (4.2) [M . H2O .Me]+, 293 (13.0), 259 (18.5), 245 (12.8), 217 (13.5), 189 (13.0), 175 (18.1), 147 (14.4), 117 (40.6), 73 (100) [SiMe3]+. ; ; ; ; ; ; &O &O ; ; ; ; ; ; &O &O ; ; ; ; ; ; 2+ 2+ ; ; ; ; ; ; 2+ +2 ; ; ; ; ; ; 2 +2 (W1 ; 6L0HQ Q Scheme 1 ¢Ô Crystallographic data for 3: C10H32O2Si6, M = 352.90, F(000) = 1536, monoclinic crystals, space group C2/c, a = 17.662(4) A, b = 10.066(2) A, c = 26.040(5) A, b = 107.09(3)¡Æ, V = 4425(2) A3, Z = 8, dcalc = 1.059 g cm.3, m(MoK¥á) = 0.372 mm.1.Intensities of 5460 reflections were measured with a Siemens P3/PC diffractometer at ambient temperature [l(MoK¥á) = = 0.71072 A, q/2q scan, 2q < 56¡Æ], and 5285 independent reflections (Rint = = 0.0277) were used in a further refinement.The structure was solved by a direct method and refined by the full-matrix least-squares technique against F2 in the anisotropic.isotropic approximation. Hydrogen atoms were located from the Fourier synthesis and refined in the isotropic approximation. An analysis of the Fourier electron density synthesis revealed additional maxima in the regions of shortest intermolecular O¡�¡�¡�O contacts, which were interpreted as a disorder of hydroxyl groups [H(1), H(1') and H(2), H(2')].The refinement converged to wR2 = = 0.1038 and GOF = 0.938 for all independent reflections [R1 = 0.0315 was calculated against F for 4512 observed reflections with I > 2s(I)]. All calculations were performed using SHELXTL-97 V5.106 on an IBM PC.Atomic coordinates, bond lengths, bond angles and thermal parameters have been deposited at the Cambridge Crystallographic Data Centre (CCDC). For details, see ¡®Notice to Authors¡�, Mendeleev Commun., Issue 1, 2001. Any request to the CCDC for data should quote the full literature citation and the reference number 1135/97. C(9) Si(6) C(10) C(1) Si(1) O(1) C(7) C(8) Si(5) Si(2) C(3) O(2) Si(3) C(4) C(6) Si(4) C(5) C(2) Figure 1 Molecular structure of 3.Hydrogen atoms are omitted for clarity. Selected bond lengths (A): Si(1).O(1) 1.671(3), Si(1).Si(6) 2.346(3), Si(1).Si(2) 2.350(2), Si(2).Si(3) 2.353(3), Si(3).O(2) 1.663(3), Si(3).Si(4) 2.349(2), Si(4).Si(5) 2.334(2), Si(5).Si(6) 2.334(2), Si.C 1.872.1.897; selected bond angles (¡Æ): O(1).Si(1).C(1) 106.7(1), O(1).Si(1).Si(6) 107.6(1), C(1).Si(1).Si(6) 111.8(1), O(1).Si(1).Si(2) 111.04(7), O(2).Si(3).C(4) 107.0(1), O(2).Si(3).Si(4) 110.42(6), O(2).Si(3).Si(2) 109.59(6), Si(1).Si(2).Si(3) 115.47(3), Si(4).Si(3).Si(2) 111.63(3), Si(5).Si(4).Si(3) 112.73(3), Si(6).Si(1).Si(2) 111.35(3), Si(5).Si(6).Si(1) 108.5(1); torsion angles (¡Æ): Si(1).Si(2).Si(3).Si(4) 45.33(2), Si(2).Si(3).Si(4).Si(5) .46.18(4), Si(3).Si(4).Si(5).Si(6) 55.35(2), Si(4).Si(5).Si(6).Si(1) .59.68(4), Si(2).Si(1). Si(6).Si(5) 56.42(4), Si(6).Si(1).Si(2).Si(3) .51.52(4).Mendeleev Communications Electronic Version, Issue 5, 2001 2 hydrogen atoms of hydroxyl groups may explain the elongation of both of the adjacent Si–Si bonds. In the crystal of 3, molecules are linked by hydrogen bonds into infinite chains along the a axis (Figure 2).This work was supported by the Russian Foundation for Basic Research (grant nos. 00-03-33189, 00-15-97359 and 01-03-06231). References 1 W. Wojnowski, B. Dreczewski, A. Herman, K. Peters, E. M. Peters and H. G. von Sehnering, Angew. Chem., Int. Ed. Engl., 1985, 24, 992. 2 E. Hengge und M. Eidl, J. Organomet.Chem., 1992, 428, 335. 3 F. K. Mitter und E. Hengge, J. Organomet. Chem., 1987, 332, 47. 4 A. Spielberger, P. Gspaltl, H. Siegl, E. Hengge and K. Gruber, J. Organomet. Chem., 1995, 499, 241. 5 R.West, in Comprehensive Organometallic Chemistry II, eds. G.Wilkinson, A. G. F. Stone and E. Abel, Elsevier, Amsterdam, 1995, vol. 2, p. 95. 6 G.M.Sheldrick, SHELXTL-97 V5.10, Bruker AXS Inc., Madison, USA, 1997. H(1A) O(1A) H(2B) H(1A)' O(2B) H(2B)' H(2A) O(2A) H(1B) H(2A)' O(1B) H(1B)' Figure 2 H-bonded chains in 3. The second position of the hydroxyl hydrogen atom is shown by an open line. The parameters of H-bonds are: O(1A)–H(1A)'···O(2B): O(2B)···H(1A)' 1.69 Å, O(1A)···O(2B) 2.818(2) Å, O(1A)–H(1A)–O(2B) 136°; O(2B)–H(2B)···O(1A): O(1A)···H(2B) 1.91 Å, O(1A)···O(2B) 2.818(2) Å, O(2B)–H(2B)–O(1A) 163°; O(2A)– H(2A)'··· O(2B): O(2B)&middo·H(2A) 1.69 Å, O(2A)···O(2B) 2.701(2) Å, O(2A)–H(2A)'– O(2B) 169°; O(2B)–H(2B)'···O(2A): H(2B)'···O(2B) 1.03 Å, O(2A)···O(2B) 2.701(2) Å, O(2A)–H(2A)'–O(2B) 169°. Received: 13th June 2001; Com. 01/1810

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 An alternative reaction of ortho-(N-benzylidene)aminophenol with chlorophosphites: formation of 2-(2'-alkoxy)-2-oxo-3-phenyl-5,6-benzo-1,4,2-oxazaphosphorinanes Mudaris N. Dimukhametov,* Eugenia V. Bajandina, Elena Yu. Davydova, Alexey B. Dobrynin, Aidar T. Gubaidullin, Igor A. Litvinov and Vladimir A. Alfonsov A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Centre of the Russian Academy of Sciences, 420088 Kazan, Russian Federation.Fax: +7 8432 75 5322; e-mail: mudaris@iopc.kcn.ru 10.1070/MC2001v011n05ABEH001478 The reactions of o-(N-benzylidene)aminophenol with ethylene chlorophosphite and diethyl chlorophosphite in CHCl3 in the absence of an external acceptor of HCl result in the formation of diastereomeric 2-(2'-alkoxy)-2-oxo-3-phenyl-5,6-benzo-1,4,2-oxazaphosphorinanes different in the configurations of phosphorus atoms.The reactions of PIII halides with compounds which contain both a hydroxy group and an imino C=N unit have not been widely studied. Several papers describe the formation of polycyclic phosphoranes via the reaction of Cl.PIII derivatives with phenols containing an imino group in the presence of a base.1.3 We have observed an alternative reaction pathway in similar systems.Here we report the reactions of o-(N-benzylidene)- aminophenol 1 with ethylene chlorophosphite and diethyl chlorophosphite. These reactions¢Ó were carried out in the absence of an external HCl acceptor, and they resulted in the formation of two stereoisomers (diastereomers A and B) of 2-(2'-alkoxy)-2-oxo- 3-phenyl-5,6-benzo-1,4,2-oxazaphosphorinanes 4 and 5 differing only in the configuration at the phosphorus atom.The diastereomeric ratio A:B in both cases was approximately equal to 2:1. Diastereomers 4A and 4B (from the reaction of imine 1 with ethylene chlorophosphite) and diastereoisomer 5A (from the reaction of imine 1 with diethyl chlorophosphite) were isolated by column chromatography on silica gel as air-stable colourless crystals.The structures of 2-(2'-chloroethoxy)-2-oxo-3-phenyl- 5,6-benzo-1,4,2-oxazaphosphorinane diastereomers 4A and 4B were determined by X-ray¢Ô diffraction analysis (Figure 1). The structures of products 5A and 5B formed in the reaction of imine 1 with diethyl chlorophosphite were determined by comparing their 1H NMR and IR spectra with those of diastereomers 4A and 4B.¡× In the 1H NMR spectrum of diastereomer 4A, the proton of the PCH fragment appears at d 4.81 ppm, whereas the analogous proton of diastereomer 4B occurs at a lower field (d 4.94 ppm).In addition, the magnitude of the geminal coupling 2JHP in 4A is approximately twice lower than that for diastereomer 4B. The 1H NMR spectrum of a mixture of the two diastereomers of 2-(2'-ethoxy)-2-oxo-3-phenyl-5,6-benzo-1,4,2-oxazaphosphor- ¢Ó A typical experimental procedure was as follows: A solution of 1 (7.1 mmol) in CHCl3 (5 ml) was added dropwise to a solution of 2 (7.1 mmol) in CHCl3 (10 ml) in a dry argon atmosphere, with cooling (10 ¡ÆC) and stirring.After stirring for 10 min at this temperature, the reaction mixture was warmed slowly to room temperature and additionally stirred for 2 h; then, it was evaporated to dryness in a vacuum.The residue was purified by column chromatography (silica gel; toluene. acetonitrile, 4:1). OH N CHPh 1 + (RO)2PCl CHCl3 OP(OR)2 N CHPh 2 H Cl (RO)2 = OCH2CH2O, (EtO)2 N P(OR)2 O Ph H Cl 3 N P O Ph H O OR' 4A,B R' = CH2CH2Cl 5A,B R' = Et Scheme 1 ¢Ô X-ray diffraction analysis.Crystallographic data for 4A and 4B at 20 ¡ÆC: crystals of C15H15ClNO3P 4A are orthorhombic, space group P212121, a = 8.857(6) A, b = 10.532(2) A, c = 16.40(1) A, V = 1529.5(1) A3, Z = 4, M = 323.72, dcalc = 1.41 g cm.3, m(CuK¥á) = 3.327 cm.1, F(000) = 672; crystals of C15H15ClNO3P 4B are monoclinic, space group P21/c, a = 8.70(2) A, b = 16.698(6) A, c = 10.942(6) A, b = 102.10(5)¡Æ, V = 1554.8(4) A3, Z = 4, M = 323.72, dcalc = 1.38 g cm.3, m(CuK¥á) = 3.273 cm.1, F(000) = 672.Intensities of 1816 reflections for M10 and 2377 reflections for M11 were measured on an Enraf Nonius CAD-4 diffractometer at 20 ¡ÆC (l CuKa radiation, w/2q scan technique, 2qmax < 144¡Æ for M10 and 114¡Æ for M11), of which 1710 and 2068 were with I > 3s for M10 and M11, respectively.The structures were solved by direct methods and difference Fourier syntheses using the SIR program4 and the MolEN package.5 All nonhydrogen atoms were refined anisotropically; H atoms located in .F maps were refined isotropically. The absolute crystal structure and the absolute configuration of a molecule of 4A were determined by the Hamilton test ratio6 with a probability of 95%.The final agreement factors are R 0.034, Rw 0.044 based on 1643 reflections with F2 ©ø 3s for 4A and R 0.034, Rw 0.046 based on 1955 reflections with F2 ©ø 3s for 4B. Atomic coordinates, bond lengths, bond angles and thermal parameters have been deposited at the Cambridge Crystallographic Data Centre (CCDC).For details, see ¡®Notice to Authors¡�, Mendeleev Commun., Issue 1, 2001. Any request to the CCDC for data should quote the full literature citation and the reference number 1135/96. ¡× 1H and 31P NMR spectra (solvent: CD3CN) were measured on Bruker WM-250 (1H, 250 MHz, TMS) and Bruker MSL-400 (31P, 162 MHz, 85% H3PO4) instruments. IR spectra were recorded on a UR-20 spectrometer. Compound 4.Overall yield of diastereomers 4A + 4B is 73%. Diastereomer 4A: mp 149.150 ¡ÆC. 1H NMR, d: 3.51 (m, 2H, CH2Cl), 3.91 (m, 1H, OCH), 4.08 (m, 1H, OCH'), 4.81 (d, 1H, CHP, 2J 10.6 Hz), 6.80.7.04 (m, 4H, C6H4), 7.44.7.60 (m, 5H, Ph). 31P NMR, d: 10.6. IR (vaseline oil, KBr, n/cm.1): 1030, 1043 (P.O.C), 1222, 1252 (P=O), 3275 (N.H). Found (%): C, 55.74; H, 4.68; Cl, 10.48; N, 4.38; P, 9.31.Calc. for C15H15ClNO3P (%): C, 55.64; H, 4.64; Cl, 10.97; N, 4.33; P, 9.58. Diastereomer 4B: mp 90.91 ¡ÆC. 1H NMR, d: 3.76 (m, 2H, CH2Cl), 4.37 (m, 2H, OCH2), 4.94 (d, 1H, CHP, 2J 20.4 Hz), 6.76.7.05 (m, 4H, C6H4), 7.39 (m, 5H, Ph). 31P NMR, d: 11.2. IR (vaseline oil, KBr, n/cm.1): 1038, 1088 (P.O.C), 1230, 1250 (P=O), 3253 (N.H). Found (%): C, 55.85; H, 4.41; Cl, 11.21; N, 4.19; P, 9.12.Calc. for C15H15ClNO3P (%): C, 55.64; H, 4.64; Cl, 10.97; N, 4.33; P, 9.58. Compound 5. Overall yield of diastereomers 5A + 5B is 79%. Diastereomer 5A: mp 138.139 ¡ÆC. 1H NMR, d: 1.08 (t, 3H, Me, 3J 7.5 Hz), 3.83 (m, 1H, OCH), 3.97 (m, 1H, OCH'), 4.78 (d, 1H, CHP, 2J 11.4 Hz), 6.81.7.03 (m, 4H, C6H4); 7.39.7.62 (m, 5H, Ph). 31P NMR, d: 10.3.IR (vaseline oil, KBr, n/cm.1): 1035 (P.O.C), 1205, 1260 (P=O), 3292 (N.H). Found (%): C, 62.44; H, 5.60; N, 4.78; P, 10.68. Calc. for C15H16NO3P (%): C, 62.28; H, 5.54; N, 4.84; P, 10.78. Mixture of diastereomers 5A + 5B, 1:1.3. Light-brown oil, nD 20 1.5670. IR (KBr, n/cm.1): 1025, 1035, 1070 (P.O.C), 1210, 1223, 1260 (P=O), 3280, 3292 (N.H). Found (%): C, 62.02; H 5.16; N 4.19; P 9.12.Diastereomer 5B: 1H NMR, d: 1.26 (t, 3H, Me, 3J 7.1 Hz), 4.23 (m, 2H, OCH2), 4.87 (d, 1H, CHP, 2J 19.5 Hz), 6.75.7.07 (m, 4H, C6H4), 7.27.7.78 (m, 5H, Ph). 31P NMR, d: 12.0.Mendeleev Communications Electronic Version, Issue 5, 2001 2 inane 5 formed in the reaction of imine 1 with diethyl chlorophosphite shows two doublets at d 4.76 (J 11.4 Hz) and 4.87 ppm (J 19.5 Hz).The 1H NMR spectrum of the isolated product 5A exhibits a doublet at d 4.78 ppm (J 11.4 Hz). Based on this observation and the earlier result for diastereomers 4A and 4B, we can conclude that the isolated diastereomer of 5 has the structure of 5A, which is analogous to diastereomer 4A, i.e., the alkoxy group in both cases adopts an axial orientation. The IR spectra of diastereomers 4A, 4B, 5A and 5B are similar with the most characteristic absorption band for the secondary amino group NH at 3250–3280 cm–1.The formation of 1,4,2-oxazaphosphorinanes 4 and 5 in the course of the reaction of 1 with chlorophosites can be illustrated by Scheme 1. Initially formed iminium salts 2 undergo intramolecular cyclization by the nucleophilic attack of the PIII atom at the electrophilic carbon atom of the imonium group, resulting in the formation of quasiphosphonium salts 3.The latter give final products 4 and 5 according to the second stage of the Arbuzov reaction. References 1 A. Schmidpeter and J. H. Weinmaier, Angew. Chem., 1975, 87, 517. 2 A. Schmidpeter and J. H. Weinmaier, Chem. Ber., 1978, 111, 2086. 3 S. D. Harper and A.J. Arduengo, J. Am. Chem. Soc., 1982, 104, 2497. 4 A. Altomare, G. Cascarano, C. Giacovazzo and D. Viterbo, Acta Crystallogr., 1991, A47, 744. 5 L. Straver and A. J. Schierbeek, MolEN, Structure Determination System, Nonius B.V., 1994, vol. 1, p. 180. 6 W. C. Hamilton, Acta Crystallogr., 1965, 18, 502. C(17) C(18) C(16) C(15) C(13) N(4) C(3) C(5) C(6) C(7) C(8) C(9) C(10) C(14) O(1) P(2) O(2) O(3) C(11) C(12) Cl(2) Cl(2) C(12) C(11) O(3) P(2) O(1) O(2) C(17) C(16) C(15) C(14) C(13) N(4)C(3) C(5) C(6) C(7) C(8) C(9) C(10) C(18) Figure 1 Molecular structure of diastereomers A,B of compound 4.For 4A, selected bond lengths (Å) : P(2)–O(1) 1.569(2), P(2)–O(2) 1.466(2), P(2)–O(3) 1.572(2), P(2)–C(3) 1.815(2), N(4)–C(3) 1.450(3), N(4)–C(5) 1.394(3), O(1)–C(6) 1.407(3), C(5)–C(6) 1.402(3), C(3)–C(13) 1.511(3); selected bond angles (°): O(1)–P(2)–O(2) 113.0(1), O(1)–P(2)–O(3) 101.8(1), O(1)–P(2)–C(3) 103.0(1), O(2)–P(2)–O(3) 114.9(1), O(2)–P(2)–C(3) 115.5(1), O(3)–P(2)–C(3) 107.0(1), P(2)–O(1)–C(6) 124.5(2), P(2)–O(3)–C(11) 122.9(2), C(3)–N(4)–C(5) 117.6(2), P(2)–C(3)–N(4) 107.1(2), P(2)–C(3)–C(13) 110.4(2), N(4)–C(3)–C(13) 113.6(2), N(4)–C(5)–C(6) 121.1(2), O(1)–C(6)–C(5) 121.2(2), O(1)–C(6)–C(7) 116.8(2).For 4B, selected bond lengths (Å): P(2)–O(1) 1.584(1), P(2)–O(2) 1.459(2), P(2)–O(3) 1.559(1), P(2)–C(3) 1.810(2), N(4)– C(3) 1.457(2), N(4)–C(5) 1.386(2), O(1)–C(6) 1.413(2), C(5)–C(6) 1.390(2), C(3)–C(13) 1.509(2); selected bond angles (°): O(1)–P(2)–O(2) 113.39(8), O(1)–P(2)–O(3) 102.83(7), O(1)–P(2)–C(3) 102.76(8), O(2)–P(2)–O(3) 115.74(7), O(2)–P(2)–C(3) 116.68(8), O(3)–P(2)–C(3) 103.65(8), P(2)– O(1)–C(6) 120.5(1), P(2)–O(3)–C(11) 121.6(1), C(3)–N(4)–C(5) 122.2(1), P(2)–C(3)–N(4) 105.9(1), P(2)–C(3)–C(13) 111.8(1), N(4)–C(3)–C(13) 111.7(1), N(4)–C(5)–C(6) 122.7(1), O(1)–C(6)–C(5) 120.7(1), O(1)–C(6)– C(7) 116.9(2). 4A 4B Received: 22nd May 2001; Com. 01/1804

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 Synthesis of 1,5-dihydro-3-methyl-6-trihalomethyl-4H-pyrazolo[3,4-d]pyrimidin-4-ones Mikhail V. Vovk,* Andrei V. Bol¡�but, Vyacheslav I. Boiko, Vladimir V. Pirozhenko and Aleksandr N. Chernega Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 02094 Kiev, Ukraine. Fax: +380 44 543 6843; e-mail: hetfos@ukrpack.net 10.1070/MC2001v011n05ABEH001479 N-(Methoxycarbonyl)trihaloacetimidoylchlorides react with 5-aminopyrazoles under mild conditions to give N-methoxycarbonyl- N'-(5-pyrazolyl)trihaloacetamidines, which furnish 6-trihalomethyl-4H-pyrazolo[3,4-d]pyrimidin-4-ones by thermal intramolecular cyclocondensation. Pyrazolo[3,4-d]pyrimidines represent a general class of adenosine receptor antagonists.1,2 Their effect on adenosine receptor selectivity is determined by the nature of substituents at the atoms N(1), C(4) and C(6).3.5 The starting substances for the preparation of 4-subsituted 1H-pyrazolo[3,4-d]pyrimidines6 are 4H-pyrazolo[ 3,4-d]pyrimidin-4-ones, which are obtained by the condensation of 5-amino-1H-pyrazole-4-carboxamides with formamide6 or esters.7 In particular, 4H-pyrazolo[3,4-d]pyrimidin-4-ones containing alkyl, phenyl and alkoxycarbonyl substituents at the 6-position can be synthesised.Here we report a new synthetic approach to 6-trihalomethyl-4H-pyrazolo[3,4-d]pyrimidin-4-ones. The introduction of trifluoromethyl groups into the above molecules is expected to enhance their lipophilicity.8,9 In turn, a trichloromethyl group facilitates the introduction of amino groups at the 6-position by ipso substitution.10 The method proposed is based on the use of N-(methoxycarbonyl) trihaloacetimidoylchlorides 1a,b11 as new synthetic units, which react with 2-aminopyrazoles 2a.d to form a pyrimidine ring.We found that compounds 1a,b react with 1-alkyl(aryl, hetaryl)- 5-aminopyrazoles 2a.d in benzene at room temperature in the presence of triethylamine to give N-methoxycarbonyl-N'-(5-pyrazolyl) trihaloacetamidines 3a.g in high yields.The structures of these compounds corroborated by elemental analysis and spectroscopy.¢Ó 1H NMR signals from 4-H protons of the pyrazole ring observed at 5.90.6.09 ppm for compounds 3a.f (and at 6.68 ppm for compound 3g) unambiguously confirm the N-acylation of amines 2a.d by imidoylchlorides 1a,b.On boiling N-(methoxycarbonyl)amidines 3a.e,g in toluene and amidine 3f in o-xylene for 3 h, they were converted into 3-methyl-6-trihalomethyl-4H-pyrazolo[3,4-d]pyrimidin-4-ones 4a.g in satisfactory or high yields.¢Ô The cyclization most likely occurs through the electrophilic attack of the carbonyl group at the ¥�-electron-rich C-4 atom of the pyrazole ring.However, the thermolysis of N-(methoxycarbonyl) amidine to isocyanate,12,13 a more electrophilic system, which in fact attacks the pyrazole nucleus, can also take place. The structure of compounds 4a.g was supported by elemental analysis and IR, 1H, 19F and 13C NMR spectroscopic data and X-ray diffraction analysis, which was carried out for 4g (Figure 1).The N(1.4)C(1.5) bicyclic system is planar: the atom devia- N Cl X3C COOMe N N Me H2N R NEt3 . NEt3¡�HCl N N Me N R N X3C MeOOC H 1a,b 2a.d . MeOH . HN N N N R O X3C Me 3a.g 4a.g 1a X = F 3a, 4a X = F, R = CH2CH2CN 1b X = Cl 3b, 4b X = Cl, R = CH2CH2CN 2a R = CH2CH2CN 3c, 4c X = F, R = Ph 2b R = Ph 3d, 4d X = Cl, R = Ph 2c R = 2-Cl-5-CF3C6H3 3e, 4e X = F, R = 2-Cl-5-CF3C6H3 2d R = 2-pyridyl 3f, 4f X = Cl, R = 2-Cl-5-CF3C6H3 3g, 4g X = Cl, 2-pyridyl Scheme 1 ¢Ó Melting points were determined using a Thomas.Hoover apparatus.The IR spectra were measured in KBr pellets. The 1H, 13C and 19F NMR spectra were measured at 300.0, 75.5, and 282.24 MHz, respectively, in [2H6]DMSO with SiMe4 (1H and 13C) and CFCl3 (19F) internal standards. The general procedure for the preparation of N-methoxycarbonyl-N'- (5-pyrazolyl)trihaloacetamidines 3a.g.A solution or suspension of aminopyrazole 2a.d (5 mmol) and triethylamine (5 mmol, 0.69 ml) in benzene (10 ml) was added to a solution of imidochloride 1a,b (5 mmol) in benzene (10 ml) with stirring at room temperature. After additional stirring for 2 h, the mixture was heated to boiling, and the resulting triethylamine hydrochloride precipitate was filtered off.The filtrate was evaporated, and the residue was crystallised from benzene. N'-[1-(2-Cyanoethyl)-3-methyl-1H-pyrazol-5-yl]-N-methoxycarbonyltrifluoroacetamidine 3a: yield 85%, mp 91.92 ¡ÆC. 1H NMR, d: 2.28 (s, 3H, Me), 2.88 (t, 2H, CH2, J 6.9 Hz), 3.79 (s, 3H, OMe), 4.59 (t, 2H, CH2N, J 6.9 Hz), 5.91 (s, 1H, 4-Hpyrazole), 7.32 (s, 1H, NH). 19F NMR, d: .71.5 (s, CF3). IR (n/cm.1): 3090 (NH), 2260 (CN), 1735 (C=O). Found (%): C, 43.64; H, 4.14; N, 22.78; F, 18.64. Calc. for C11H12F3N5O2 (%): C, 43.57; H, 3.99; N, 23.09; F, 18.80. N'-[1-(2-Cyanoethyl)-3-methyl-1H-pyrazol-5-yl]-N-methoxycarbonyltrichloroacetamidine 3b: yield 87%, mp 138.139 ¡ÆC. 1H NMR, d: 2.27 (s, 3H, Me), 2.91 (t, 2H, CH2, J 7.2 Hz), 3.74 (s, 3H, OMe), 4.52 (t, 2H, CH2N, J 7.2 Hz), 5.90 (s, 1H, 4-Hpyrazole), 7.34 (s, 1H, NH).IR (n/cm.1): 3075 (NH), 2260 (CN), 1730 (C=O). Found (%): C, 37.70; H, 3.44; N, 19.75; Cl, 30.35. Calc. for C11H12Cl3N5O2 (%): C, 37.47; H, 3.43; N, 19.86; Cl, 30.16. N-Methoxycarbonyl-N'-(3-methyl-1-phenyl-1H-pyrazol-5-yl)trifluoroacetamidine 3c: yield 96%, mp 111.112 ¡ÆC. 1HNMR, d: 2.35 (s, 3H, Me), 3.75 (s, 3H, OMe), 6.01 (s, 1H, 4-Hpyrazole), 7.31 (t, 1H, 4'-H, J 6.6 Hz), 7.42 (m, 2H, 3'-H, 5'-H), 7.51 (s, 1H, NH), 7.59 (d, 2H, 2'-H, 6'-H, J 7.6 Hz). 19F NMR, d: .71.9 (s, CF3). IR (n/cm.1): 3100 (NH), 1740 (C=O). Found (%): C, 51.79; H, 3.83; N, 17.41; F, 17.56. Calc. for C14H13F3N4O2 (%): C, 51.54; H, 4.02; N, 17.17; F, 17.47. N-Methoxycarbonyl-N'-(3-methyl-1-phenyl-1H-pyrazol-5-yl)trichloroacetamidine 3d: yield 95%, mp 112.113 ¡ÆC. 1H NMR, d: 2.25 (s, 3H, Me), 3.83 (s, 3H, OMe), 5.93 (s, 1H, 4-Hpyrazole), 6.95 (t, 1H, 4'-H, J 6.8 Hz), 7.12 (m, 2H, 3'-H, 5'-H), 7.56 (s, 1H, NH), 7.90 (d, 2H, 2'-H, 6'-H, J 7.9 Hz). IR (n/cm.1): 3080 (NH), 1745 (C=O). Found (%): C, 44.38; H, 3.65; N, 15.07; Cl, 21.59. Calc. for C14H13Cl3N4O2 (%): C, 44.76; H, 3.49; N, 14.92; Cl, 28.31.N'-{1-[2-Chloro-5-(trifuoromethyl)phenyl]-3-methyl-1H-pyrazol-5-yl}- N-methoxycarbonyltrifluoroacetamidine 3e: yield 68%, mp 127.128 ¡ÆC. 1H NMR, d: 2.38 (s, 3H, Me), 3.82 (s, 3H, OMe), 6.06 (s, 1H, 4-Hpyrazole), 7.29 (s, 1H, NH), 7.64 (s, 2H, 3'-H, 4'-H), 7.74 (s, 1H, 6'-H). 19F NMR, d: .63.9 (s, CF3), .71.6 (s, CF3). IR (n/cm.1): 3100 (NH), 1740 (C=O). Found (%): C, 42.11; H, 2.69; N, 13.32; F, 26.38.Calc. for C15H11ClF6N4O2 (%): C, 42.02; H, 2.59; N, 13.07; F, 26.59. N'-{1-[2-Chloro-5-(trifuoromethyl)phenyl]-3-methyl-1H-pyrazol-5-yl}- N-methoxycarbonyltrichloroacetamidine 3f: yield 77%, mp 160.161 ¡ÆC. 1H NMR, d: 2.38 (s, 3H, Me), 3.77 (s, 3H, OMe), 6.09 (s, 1H, 4-Hpyrazole), 7.26 (s, 1H, NH), 7.62 (s, 2H, 3'-H, 4'-H), 7.76 (s, 1H, 6'-H).IR (n/cm.1): 3100 (NH), 1735 (C=O). Found (%): C, 37.71; H, 2.45; N, 11.47; Cl, 29.43. Calc. for C15H11Cl4F3N4O2 (%): C, 37.68; H, 2.32; N, 11.72; Cl, 29.66. N-Methoxycarbonyl-N'-[3-methyl-1-(2-pyridinyl)-1H-pyrazol-5-yl]trichloroacetamidine 3g: yield 73%, mp 139.140 ¡ÆC. 1H NMR, d: 2.32 (s, 3H, Me), 3.83 (s, 3H, OMe), 6.68 (s, 1H, 4-Hpyrazole), 7.16 (m, 1H, Hpyridine), 7.86.8.04 (m, 3H, Hpyridine), 13.6 (s, 1H, NH).IR (n/cm.1): 3100 (NH), 1725 (C=O). Found (%): C, 41.69; H, 3.07; N, 18.84; Cl, 28.60. Calc. for C13H12Cl3N5O2 (%): C, 41.46; H, 3.21; N, 18.59; Cl, 28.24.Mendeleev Communications Electronic Version, Issue 5, 2001 2 tions from the least-squares plane do not exceed 0.04 A, the dihedral angle between N(1)N(2)C(1.3) and N(3)N(4)C(3.5) cycles being only 2.9¡Æ.The N(5)C(8.12) ring is turned out from the bicyclic plane by 23.0¡Æ. In a crystal, molecules of 4g are joined in dimeric pairs by the intermolecular hydrogen bonds N(1).H(1)¡�¡�¡

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 Heterocyclization of N-[2-(cyclopent-1-enyl)phenyl]acetamides and ethyl N-[2-(cyclopent-1-enyl)phenyl]carbamates under the action of hydrogen peroxide Rail R. Gataullin,* Marat F. Nasyrov, Ol’ga V. Shitikova, Leonid V. Spirikhin and Il’dus B. Abdrakhmanov Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, 450054 Ufa, Russian Federation.Fax: +7 3472 35 6066; e-mail: chemorg@anrb.ru 10.1070/MC2001v011n05ABEH001489 The oxidation of N-[2-(cyclopent-1-enyl)phenyl]acetamides and ethyl N-[6-methyl-2-(cyclopent-1-enyl)phenyl]carbamate with hydrogen peroxide in methanolic NaOH gave spiro[4H-3,1-benzoxazine-4,1'-cyclopentanes]. On the other hand, ethyl [2-(cyclopent- 1-enyl)phenyl]carbamate reacted with hydrogen peroxide in the presence of acetonitrile and NaOH to give ethyl 3a-hydroxy- 2,3,3a,8b-tetrahydrocyclopenta[b]indole-4(1H)-carboxylate, which was dehydrated with polyphosphoric acid to ethyl 2,3-dihydrocyclopenta[ b]indole-4(1H)-carboxylate.Benzoxazine derivatives exhibit considerable activity in the inhibition1 of chymase or reverse transcriptase of HIV-1.2 Recently, we have reported a convenient synthesis of 3,1-benzoxazines from ortho-(alk-1-enyl)anilides under the action of hydrogen chloride or bromine.3,4 At present, the cyclization of these anilides under the effect of oxidising agents as hydrogen peroxide has not been studied.In order to search for new methods of controllable heterocyclization of ortho-alkenylanilines, the effect of hydrogen peroxide on acetamides 1a,b and carbamates 1c,d† has been studied. Therefore, the reaction of 1a3 or 1c with hydrogen peroxide in the presence of sodium hydroxide in acetonitrile and methanol as solvents gave 8-methylspiro[4H-3,1-benzoxazine- 4,1'-cyclopentanes] 2a or 2c.‡ Under the same reaction conditions, carbamate 1d gave ethyl 3a-hydroxy-2,3,3a,8b-tetrahydrocyclopenta[ b]indole-4(1H)-carboxylate 4, the effect of polyphosphoric acid on which caused dehydration and gave ethyl 2,3-dihydrocyclopenta[b]indole-4(1H)-carboxylate 5.§ Compounds 1a–d were found to be sensitive to oxidation conditions.The interaction of 1d with H2O2 in the presence of Na2WO4 and H3PO4 resulted in 3,1-benzoxazinone 3. Under these conditions, amide 1b gives benzoxazine 2b in 85% yield.¶ Under the same conditions, anilides 1a and 1c did not react.To clarify the mechanism of the formation of 4, the wellknown reaction of aryl(cycloalk-1-enes) bearing no amine moiety with hydrogen peroxide, which leads to arylcycloalkylketones should be taken into account.5 Probably, 4 is formed by the intramolecular cyclization of intermediate A (Scheme 1), which was not detected in the reaction mixture most probably because of its high reactivity under alkaline conditions.The structure of compounds 1b–d, 2a–c, 3–5 was determined using spectral methods and elemental analyses. † General methods. 1H and 13C NMR spectra were recorded using a Bruker AM-300 spectrometer at 300.13 and 75.47 MHz (with Me4Si as an internal standard).IR spectra were recorded on a Specord M-80 spectrophotometer. The purity of initial compounds and reaction products was controlled with a Chrom 5 instrument and Silufol UV 25 plates. Mass spectra were recorded using an MH 1320 spectrometer (70 eV). Acetamide 1b was obtained according to the published method3 by the reaction of ortho-(cyclopent-1-enyl)aniline6 with acetic anhydride.General procedure for the synthesis of carbamates 1c and 1d. Ethyl chloroformate (1.3 g, 12 mmol) was added dropwise to a vigorously stirred mixture of ortho-(cyclopent-1-enyl)aniline6 or 2-methyl-6-(cyclopent- 1-enyl)aniline3 (10 mmol) and potassium carbonate (2.76 g, 20 mmol) in dichloromethane (20 ml) at 20 °C. After 1 h, water (2 ml) was added, the mixture was stirred, the precipitate was filtered off, and the filtrate was washed with water and dried (MgSO4).The solvent was evaporated in a vacuum, the products were isolated as a yellowish oil. 1c: yield 95%, mp 51–53 °C. 1H NMR (CDCl3) d: 1.30 (t, 3H, Me, J 7.31 Hz), 1.90–2.70 (m, 6H, 3CH2), 2.30 (s, 3H, Me), 4.15 (m, 2H, CH2), 5.90 (s, 1H, CH), 6.35 (s, 1H, NH), 7.10 (m, 3H, Ar). 13C NMR (CDCl3) d: 14.65 (Me), 18.34 (Me), 23.66 [C(4')], 33.51 [C(3')], 35.91 [C(5')], 61.14 (OCH2), 126.14 [C(5)], 126.73 [C(4)], 129.24 [C(2)], 130.91 [C(3)], 133.80 [C(6)], 136.37 [C(2')], 138.35 [C(1)], 141.33 [C(1')], 154.60 (C=O).Found (%): C, 73.19; H, 7.15; N, 5.43. Calc. for C15H19NO2 (%): C, 73.47; H, 7.76; N, 5.71. 1d: yield 95%, Rf 0.6 (hexane–EtOAc, 4:1). 1H NMR (CDCl3) d: 1.3 (t, 3H, Me, J 7.3 Hz), 2.0 (quint, 2H, CH2, J 7.8 Hz), 2.6 (br.s, 2H, CH2), 2.7 (br. s, 2H, CH2), 4.2 (q, 2H, CH2O, J 7.2 Hz), 5.9 (br. s, 1H, =CH), 7.0 (m, 1H, ArH), 7.1 (br. s, 1H, NH), 7.1–7.3 (m, 2H, ArH), 8.1 (d, 1H, ArH, J 8.1 Hz). 13C NMR (CDCl3) d: 14.3 (Me), 23.0, 33.5, 36.4 (3CH2), 61.0 (CH2O), 119.5 [C(6)], 122.7 [C(2')], 127.3 [C(4)], 127.5 [C(3)], 127.6 [C(2)], 129.9 [C(5)], 134.6 [C(1')], 140.3 [C(1)], 153.4 (C=O).Found (%): C, 72.68; H, 7.45; N, 5.99. Calc. for C14H17NO2 (%): C, 72.70; H, 7.41; N, 6.06. ‡ General procedure for the synthesis of spirobenzoxazinecyclopentanes 2a and 2c and tetrahydrocyclopentaindole 4. Acetamide 1a or carbamate 1c or 1d was added to a stirred solution of sodium hydroxide (0.2 g) in methanol (5 ml) and acetonitrile (5 ml).To the resulting mixture, an excess of a 50% hydrogen peroxide solution (1 g, 29.4 mmol) was added dropwise. Evolution of oxygen and an increase of the reaction temperature were observed upon standing for 2 h. A saturated sodium thiosulfate solution (10 ml) was added, extracted with dichloromethane and dried (MgSO4). The solvent was evaporated in vacuo, and the yellowish oily residue was purified by column chromatography using silica gel (5 g, eluent: hexane–EtOAc, 2:1) to give spirobenzoxazinecyclopentane 2a, which was recrystallised from ethyl acetate or spirobenzoxazinecyclopentane 2c, which crystallised upon standing or tetrahydrocyclopentaindole 4, which was obtained as an amorphous substance. 2a: yield 80%, mp 103 °C. 1HNMR (CDCl3) d: 1.7–2.0 (m, 2H, CH2), 2.1 (s, 3H, Me), 2.1–2.2 (m, 2H, CH2), 2.3 (s, 3H, Me), 2.4–2.5 (m, 2H, CH2), 2.9 (br.s, 1H, OH), 4.0 (d, 1H, CH, J 5.9 Hz), 7.0–7.3 (m, 3H, ArH). 13C NMR (CDCl3) d: 17.3, 21.8 (2Me), 20.6, 31.5, 34.4 (3CH2), 75.5 (CHOH), 90.2 [C(4)], 122.6 [C(6)], 123.5 [C(4a)], 125.4 [C(5)], 130.8 [C(7)], 132.4 [C(8)], 137.5 [C(8a)], 159.6 (C=N). MS, m/z: 231 (M+). Found (%): C, 72.45; H, 7.42; N, 6.30. Calc.for C14H17NO2 (%): C, 72.70; H, 7.41; N, 6.06. 2c: yield 63%, mp 105 °C. 1H NMR (CDCl3) d: 1.4 (t, 1H, Me, J 7.2 Hz), 1.7–2.2 (m, 6H, 3CH2), 2.3 (s, 3H, Me), 4.1 (br. s, 1H, CH–O), 4.4 (m, 2H, CH2), 5.0 (br. s, 1H, OH), 6.9–7.0 (m, 2H, ArH), 7.1 (d, 1H, ArH, J 8.1 Hz). 13C NMR (CDCl3) d: 14.2, 17.0 (2Me), 20.6, 31.4, 34.2 (3CH2), 64.3 (OCH2), 75.4 (CHOH), 93.5 [C(4)], 122.3 [C(4a)], 122.6 [C(6)], 123.2 [C(5)], 130.7 [C(7)], 131.7 [C(8)], 140.0 [C(8a)], 154.8 (C=O).Found (%): C, 68.42; H, 7.21; N, 5.40. Calc. for C15H19NO3 (%): C, 68.94; H, 7.33; N, 5.36. 4: yield 70%. 1H NMR (CDCl3) d: 1.3 (t, 3H, Me, J 7.6 Hz), 1.5–1.7 (m, 2H, CH2), 1.7–1.9 (m, 2H, CH2), 2.2–2.4 (m, 2H, CH2), 3.5–3.6 (m, 1H, CH), 4.3 (q, 2H, CH2, J 6.9 Hz), 7.0 (t, 1H, ArH, J 7.4 Hz), 7.1–7.3 (m, 3H, ArH), 7.6 (br.s, 1H, OH). 13C NMR (CDCl3) d: 14.6 (Me), 25.4 [C(2)], 34.0 [C(1)], 42.2 [C(3)], 53.2 [C(8b)], 61.9 (OCH2), 103.6 [C(3a)], 114.4 [C(5)], 123.2 [C(7)], 124.4 [C(8)], 129.0 [C(6)], 132.7 [C(8a)], 141.5 [C(4a)], 153.5 (C=O). Found (%): C, 67.83; H, 6.71; N, 5.78. Calc. for C14H17NO3 (%): C, 68.00; H, 6.93; N, 5.66. § Synthesis of tetrahydrocyclopentaindole 5.A mixture of tetrahydrocyclopentaindoline 4 (0.5 g, 2.02 mmol), phosphoric acid (85%) (3 g) and phosphorus pentoxide (2 g) was vigorously stirred and then left to stand for 10 h. The acid solution was neutralised with aqueous sodium hydroxide, extracted with benzene, and the organic extract was dried (NaOH). The solvent was evaporated to give crystalline tetrahydrocyclopentaindole 5.Yield 97%, mp 67 °C. 1H NMR (CDCl3) d: 1.4 (t, 3H, Me, J 6.2 Hz), 2.4 (q, 2H, CH2, J 7.0 Hz), 2.7 (t, 2H, CH2, J 6.8 Hz), 3.0 (t, 2H, CH2, J 6.6 Hz), 4.4 (q, 2H, CH2), 7.1–7.3 (m, 2H, ArH), 7.3 (d, 1H, J 7.4 Hz, H-8), 8.1 (d, 1H, H-5, J 6.2 Hz). 13C NMR (CDCl3) d: 14.5 (Me), 24.2, 27.5, 29.0 (3CH2), 62.8 (OCH2), 115.9 [C(5)], 118.7 [C(8)], 124.8 [C(6)], 125.1 [C(7)], 127.0 [C(8a)], 128.0 [C(8b)], 140.3 [C(3a)], 144.0 [C(4a)], 151.5 (C=O).Found (%): C, 74.01; H, 6.67; N, 6.00. Calc. for C14H15NO2 (%): C, 73.34; H, 6.59; N, 6.11.Mendeleev Communications Electronic Version, Issue 5, 2001 2 Finally, it must be concluded that the structure of products obtained (benzoxazine or indoline type) is dependent on the nature of protecting group and the type of catalysts used (tungstate –phosphoric acid or acetonitrile–alkali) despite that both of these systems are epoxydising.References 1 M.Gütschow, Sci. Pharm., 1999, 67, 524. 2 M. E. Pierce, R. L. Parsons, L. A. Radesca, Y. S. Lo, St. Silverman, J. R. Moore, Q. Islam, A. Choudhury, J. M. D. Fortunak, D. Nguyen, C. Luo, S. G. Morgan, W. P. Davis, P.N. Confalone, C. Chen, R. D. Tillyer, L. Frey, L. Tan, F. Xu, D. Zhao, A. S. Thomson, E. G. Corley, E. G. G. Grabowski, R. Robert and P. P. Reider, J. Org. Chem., 1998, 63, 8536. 3 R. R. Gataullin, I. S. Afonkin, I. V. Pavlova, A. A. Fatykhov, I. B. Abdrakhmanov and G. A. Tolstikov, Izv. Akad. Nauk, Ser. Khim., 1999, 398 (Russ. Chem. Bull., 1999, 48, 396). 4 R. R. Gataullin, I.S. Afonkin, A. A. Fatykhov, L. V. Spirikhin and I. B. Abdrakhmanov, Izv. Akad. Nauk, Ser. Khim., 2000, 118 (Russ. Chem. Bull., 2000, 49, 122). 5 E. N. Prilezhaeva, Reaktsiya Prilezhaeva. Elektrofil’noe okislenie (Prilezhaev Reaction. Electrophilic Oxidation), Nauka, Moscow, 1974, p. 332 (in Russian). 6 R. R. Gataullin, T. V. Kazhanova, A. A. Fatykhov, L. V. Spirikhin and I. B.Abdrakhmanov, Izv. Akad. Nauk, Ser. Khim., 2000, 171 (Russ. Chem. Bull., 2000, 49, 174). ¶ General procedure for the synthesis of spirobenzoxazinecyclopentane 2b and 3. A solution of sodium tungstate (50 mg, 0.17 mmol) in water (0.2 ml), one drop of conc. phosphoric acid and a solution of 50% of hydrogen peroxide (0.34 g, 4.98 mmol) were added to a solution of acetamide 1b or carbamate 1d (2.48 mmol) in methanol (5 ml).The reaction mixture was allowed to stand for 48 h at 30 °C, and then dichloromethane (50 ml) was added, washed with a saturated sodium thiosulfate solution followed by water and then the organic extracts were dried (MgSO4). The solvent was evaporated in vacuo to give an oil of spirobenzoxazinecyclopentanes 2b or 3, which crystallised on standing. 2b: yield 80%, mp 143 °C. 1H NMR (CDCl3) d: 1.7–2.0 (m, 2H, CH2), 2.0 (s, 3H, Me), 2.1–2.2 (m, 2H, CH2), 2.4–2.5 (m, 2H, CH2), 2.7 (br. s, Scheme 1 Reagents and conditions: i, H2O2, NaOH, MeCN+MeOH (1:1); ii, H2O2, Na2WO4, H3PO4; iii, PPA, 20 °C. NHC(O)R R1 1a–d a R = R1 = Me b R = Me, R1 = H c R = OEt, R1 = Me d R = OEt, R1 = H N O HO R1 R 2a–c N O HO O 3 H NHCO2Et A i, 1a–c ii, 1d i, 1d O N H OH CO2Et 4 iii N CO2Et 5 Received: 28th June 2001; Com. 01/1815 1H, OH), 4.1 (d, 1H, CH, J 4.62 Hz), 7.0 (d, 1H, J 7.59 Hz), 7.1–7.3 (m, 3H, ArH). 13C NMR (CDCl3) d: 21.5 (Me), 20.5, 31.6, 34.7 (3CH2), 75.9 (CHOH), 90.0 [C(4)], 123.5 [C(4a)], 123.6 [C(6)], 125.1 [C(7)], 125.8 [C(8)], 129.1 [C(5)], 139.1 [C(8a)], 160.3 (C=N). Found (%): C, 71.03; H, 6.82; N, 6.76. Calc. for C13H15NO2 (%): C, 71.87; H, 6.96; N, 6.45. 3: yield 85%, mp 216 °C. 1H NMR ([2H6]DMSO) d: 1.6–2.4 (m, 6H, 3CH2), 4.0 (m, 1H, CH–O), 4.9 (br. s, 1H, OH), 6.9 (d, 1H, H-5, J 8.2 Hz), 7.0 (t, 1H, ArH, J 7.6 Hz), 7.2 (t, 2H, ArH, J 7.4 Hz), 10.1 (s, 1H, NH). 13C NMR ([2H6]DMSO) d: 19.5, 32.1, 33.2 (3CH2), 74.6 (CHOH), 92.8 [C(4)], 113.5 [C(8)], 120.7 [C(4a)], 121.7 [C(6)], 126.5 [C(5)], 128.6 [C(7)], 136.0 [C(8a)], 150.7 (C=O). Found (%): C, 65.30; H, 6.02; N, 6.36. Calc. for C12H13NO3 (%): C, 65.74; H, 5.98; N, 6.39.

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Mendeleev Communications Electronic Version, Issue 5, 2001 1 Iodocyclization of N-(2-nitrophenyl)- and N-phenyl-N'-[2-(alk-1-enyl)phenyl]ethanimidamides Rail R. Gataullin, Ivan S. Afon’kin,* Akhnaf A. Fatykhov, Leonid V. Spirikhin and Il’dus B. Abdrakhmanov Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, 450054 Ufa, Russian Federation. Fax: +7 3472 35 6066; e-mail: chemorg@anrb.ru 10.1070/MC2001v011n05ABEH001490 The action of iodine on N-(2-nitrophenyl)- or N-phenyl-N'-[2-(alk-1-enyl)phenyl]ethanimidamides obtained by the condensation of 2-(cyclopent-1-enyl)-6-methylaniline with N-(1-chloroethylidene)aniline or N-(1-chloroethylidene)-2-nitroaniline results in corresponding spiro(3,4-dihydroquinazoline)-4,1'-(2'-iodocyclopentane) in good yields, but the analoguous reaction with 4-methyl-2- (1-methylbut-1-enyl)aniline leads to an N-[(2,3-dihydro-1H-indol-1-yl)ethylidene]aniline derivative. In the past few years, quinazolines and their 3,4-dihydro derivatives obtained from 2-aminomethylanilines1,2 or by the addition of alkylisocyanates to 2-aminocinnamic acid esters3 have attracted the attention of scientists due to their biological activities.Continuing our work4 on the heterocyclization of alkenylarylethanimidamides synthesised from 2-(alk-1-enyl)anilines, we now report on the interaction with I2. Therefore, the condensation of 2-(cyclopent-1-enyl)-6-methylaniline 15 with N-(1-chloroethylidene) aniline 2 or N-(1-chloroethylidene)-2-nitroaniline 36 in benzene at 80 °C gave ethanimidamides 46 or 5† in high yield (Scheme 1).The interaction of ethanimidamides 4 and 5 with iodine lead to spiro(dihydroquinazoline)cyclopentane 6 or 7. Using the Overhauser effect to determine the orientation of the H(2') proton in the cyclopentane fragment of a model of 7 suggested that the reaction proceeds via the formation of onium complex A. In contrast, the interaction of 8 with iodine obtained from amine 97 and acetanilide lead to basic reaction product indoline 10 (Scheme 2).The following reaction mechanism is proposed. Carbocation 11 resulting from the reaction of iodine with 8 loses a proton to give amidine 12. By intramolecular displacement of iodide, ion 12 cyclises to 10.‡ The structure of all new compounds was determined by spectral methods and elemental analysis.In the 1H NMR spectra of compounds 6 and 7, a signal of the H(2') proton is observed at 4.3 ppm as a double doublet with spin–spin coupling constants at 8.2–9.0 and 9.6–11.0 Hz. The high values of these constants support the axial orientation of proton H(2'). The 13C NMR spectra of compounds 6 and 7, detected in the JMOD regime, show a peak in the NH2 Me 1 X N=C(Me)Cl 2 X = H 3 X = NO2 benzene 80 °C HN Me Me N X 4 X = H 5 X = NO2 Me NH N Me X I A I2, Na2CO3, CHCl3 N N Me Me I He Ha Ha X 1 2 3 4 5 6 7 8 8a 4a 2 3 6 X = H 7 X = NO2 Scheme 1 20 °C † General methods. 1H and 13C NMR spectra were recorded using a Bruker AM-300 spectrometer at 300.13 and 75.47 MHz (with Me4Si as an internal standard). IR spectra were measured on a UR-20 instrument.Mass spectra were measured on an MX 1320 mass spectrometer (EI, 70 eV). The purity of the reaction products was checked by TCL on Silufol UV-254 plates. General procedure for the synthesis of N-(2-cyclopent-1-en-1-yl-6- methylphenyl)-N'-(2-nitrophenyl)ethanimidamide 5 and N-{4-methyl-2- [(E)-1-methylbut-1-enyl]phenyl}-N'-phenylethanimidamide 8. The corresponding acetanilide (0.02 mol) was added slowly in small portions to a stirred cooled solution of phosphorus pentachloride (4.8 g, 0.023 mol) in chloroform or benzene (20 ml).After completion of reaction, a solution of alkenylaniline 1 or 9 (0.02 mol) in chloroform or benzene (10 ml) was added slowly. The resulting reaction mixture was refluxed for 2.5 h. After cooling, it was treated with a 10% sodium hydroxide solution, extracted with chloroform or benzene and dried (MgSO4).The solvent was evaporated, and the crude residue was purified by column chromatography using silica gel to give ethanimidamide 5 or was extracted with hot hexane to give ethanimidamide 8. 5: yield 91%, yellow glassy mass. 1H NMR (CDCl3) d: 1.8–2.2 (m, 2H, CH2), 2.3 (s, 3H, Me), 2.5 (s, 3H, Me), 2.7 (m, 2H, CH2), 2.9 (m, 2H, CH2), 6.2 (s, 1H, H-2''), 7.0–7.7 (m, 5H, Ar), 8.3 (d, 1H, H-6– PhNO2, J 8.0 Hz), 9.7 (d, 1H, H-3–PhNO2, J 6.5 Hz), 10.2 (s, 1H, NH). 13C NMR (CDCl3) d: 18.3 (C-2), 19.2 [C(2')–Me], 23.3 [C(4'')], 33.3 [C(3'')], 35.1 [C(5'')], 120.4, 121.2, 122.3, 125.4, 126.1, 127.6, 128.0, 128.5, 128.6, 134.7, 135.7, 137.8, 141.7, 145.6 [CAr, C(1''), C(2'')], 151.4 [C(1)].IR, n/cm–1: 3270 (NH). Found (%): C, 71.28; H, 6.32; N, 12.11. Calc. for C20H21N3O2 (%): C, 71.62; H, 6.71; N, 12.53. 8: yield 95%, Rf 0.2 (C6H6–EtOAc, 2:1). 1H NMR (CDCl3) d: 1.0 (t, 3H, Me, J 7.5 Hz), 1.9 (m, 2H, CH2), 2.0, 2.1, 2.4 (3s, 3×3H, 3Me), 5.6 (t, H-3', J 6.9 Hz), 7.0 (s, 1H, H-3), 7.1–7.4 (m, 7H, Ar), 7.6 (s, 1H, NH). 13C NMR (CDCl3) d: 13.9, 17.0, 20.4, 24.3 (4Me), 22.3 [C(3')], 121.1 [C(6)], 127.9 [C(5)], 128.5 [C(2')], 130.7 [C(3)], 132.1 [C(2)], 133.2 [C(4)], 133.4 [C(1')], 145.2 [C(1)], 151.1 (N=C–N), 122.4, 127.7, 128.5, 130.7 (C–Ph).IR, n/cm–1: 3230 (NH). Found (%): C, 82.00; H, 8.07; N, 9.34. Calc. for C20H24N2 (%): C, 82.15; H, 8.27; N, 9.58. Me Me Me NH Me PhN Me Me NH2 Me 8 9 PhN=C(Cl)Me Me Me NH Me PhN 11 I I CH2 NH Me PhN 12 Me – H+ Me N PhN Me CH2 H Me 10 I2 Scheme 2Mendeleev Communications Electronic Version, Issue 5, 2001 2 aliphatic region, a quaternary carbon atom C(4) peak is observed at 71.5 ppm and a cyclopentane C(2') peak, at 34.0 and 35.9 ppm. The structure of compound 10 is supported by elemental analysis and spectral data.In the 1H NMR spectrum, non-equivalent alkene protons are observed at 5.2 and 5.5 ppm as two oneproton singlets, (spin–spin coupling constant is 0–2 Hz8).A peak corresponding to the H(2) proton is observed as a double doublet at 4.2 ppm (J1 5.9 Hz, J2 11.3 Hz). The two-proton multiplet peaks of the methylene group appear at 1.3–1.9 ppm and a three-proton triplet of the methyl group at 0.6 ppm (J 7.3 Hz) corresponds to the ethyl fragment. Moreover, two three-proton singlet peaks at 2.2 and 2.5 ppm correspond to the other two methyl groups.The 13C NMR data support this structure. In the aliphatic region, the five peaks observed are correlated using the method of a pulse sequence of J-modulated spin echo. Three of these signals correspond to carbon atoms of methyl groups, one to a methylene carbon atom of ethyl group, and that at low field (73.6 ppm) to the carbon atom C(2).There are 13 aromatic and olefinic peaks, where the carbon atom of the amidine group resonates at 155.0 ppm. The calculations on increments of substituents testify that these signals correspond to the given structure. The mass spectrum of compound 10 showed the presence of a molecular ion at m/z 290, as expected. Thus, the reaction path of the iodocyclization of N-[2-(alk-1- enyl)phenyl]ethanimidamides depends on the nature of alkenyl radical; thus, the derivatives of N-[2-(cyclopent-1-enyl)phenyl]- ethanimidamide gave corresponding spiro(3,4-dihydroquinazoline)- 4,1'-(2'-iodocyclopentane), but N-phenyl-N'-[2-(1-methylbut-1- enyl)phenyl]ethanimidamide gave an N-[(2,3-dihydro-1H-indol- 1-yl)ethylidene]aniline derivative.References 1 M. A. Arozome, T. Kondo and Y. Watanabe, J. Org. Chem., 1993, 58, 310. 2 V. A. Savel’ev and V. A. Loskutov, Khim. Geterotsikl. Soedin., 1991, 791 [Chem. Heterocycl. Compd. (Engl. Transl.), 1991, 27, 621]. 3 P. Molina, E. Aller and A. Lorenzo, Synthesis, 1998, 283. 4 R. R. Gataullin, T. V. Kazhanova, F. F. Minnigulov, A. A. Fatykhov, L. V. Spirikhin and I.B. Abdrakhmanov, Izv. Akad. Nauk, Ser. Khim., 2000, 1789 (Russ. Chem. Bull., 2000, 49, 1769). 5 R. R. Gataullin, I. S. Afon’kin, I. V. Pavlova, I. B. Abdrakhmanov and G. A. Tolstikov, Izv. Akad. Nauk, Ser. Khim., 1999, 398 (Russ. Chem. Bull., 1999, 48, 396). 6 R. R. Gataullin, I. S. Afon’kin, I. B. Abdrakhmanov and G. A. Tolstikov, Izv. Akad. Nauk, Ser. Khim., 2001, 522 (Russ.Chem. Bull., 2001, 50, 545). 7 R. R. Gataullin, I. S. Afon’kin, A. A. Fatykhov, L. V. Spirihin, E. V. Tal’vinskiy and I. B. Abdrakhmanov, Izv. Akad. Nauk, Ser. Khim., 2001, 633 (Russ. Chem. Bull., 2001, 50, 659). 8 B. I. Ionin, B.A. Ershov and A. I.Kol’tsov, YaMR-spektroskopiya v organicheskoi khimii (NMR Spectroscopy in Organic Chemistry), Khimiya, Leningrad, 1983 (in Russian).‡ General procedure for the synthesis of spiro(2,8-dimethyl-3-phenyl- 3,4-dihydroquinazoline)-4,1'-(2'-iodocyclopentane) 6, spiro[2,8-dimethyl- 3-(2-nitrophenyl)-3,4-dihydroquinazoline]-4,1'-(2'-iodocyclopentane) 7 and N-[(2-ethyl-5-methyl-3-methylene-2,3-dihydro-1H-indol-1-yl)ethylidene] aniline 10. A mixture of ethanimidamide 4, 5 or 8 (1 mmol), iodine (0.51 g, 2 mmol) and sodium carbonate (1.1 g, 10 mmol) in chloroform (7 ml) was stirred for 24 h at 20 °C.The progress of the reaction was monitored by TLC (CCl4 as an eluent). The reaction mixture was diluted with chloroform (30 ml), washed with a sodium thiosulfate solution (2×30 ml) and then with water (10 ml). The combined organic phases were dried (MgSO4), and the solvent was evaporated in vacuo.The residue was purified by column chromatography using silica gel (eluent: C6H6– EtOAc, 4:1) to give product 6; the recrystallization from benzene gave product 7; column chromatography using silica gel (eluent: C6H6–MeOH, 15:1) gave product 10. 6: yield 93%, amorphous solid, Rf 0.5 (C6H6–EtOAc, 2:1). 1H NMR (CDCl3) d: 1.2–2.3 (m, 6H, 3CH2), 2.0, 2.5 (2s, 2×3H, 2Me), 4.3 (dd, 1H, H-2', J1 9.0 Hz, J2 9.6 Hz), 6.8–7.5 (m, 7H, Ar). 13C NMR (CDCl3) d: 17.8, 24.8 (2Me), 23.2 [C(4')], 32.8 [C(5')], 34.0 [C(2')], 38.2 [C(3')], 71.5 [C(4)], 123.2, 125.2, 126.6, 128.3, 128.7, 130.1, 130.7, 130.8, 138.6, 138.9 (CAr), 155.8 [C(2)]. Found (%): C, 57.39; H, 4.76; I, 29.99; N, 6.34. Calc. for C20H21IN2 (%): C, 57.70; H, 5.09; I, 30.48; N, 6.73. 7: yield 95%, mp 125–127 °C, Rf 0.4 (C6H6–EtOAc, 2:1). 1H NMR (CDCl3) d: 1.3–2.3 (m, 6H, 3CH2), 2.0 (s, 3H, Me), 2.5 (s, 3H, Me), 4.3 (dd, 1H, H-2', J1 8.2 Hz, J2 11.0 Hz), 6.7–7.9 (m, 7H, Ar). 13C NMR (CDCl3) d: 17.5 [C(8')H3], 23.1 [C(4')], 24.9 [C(2')H3], 31.6 [C(5')], 33.1 [C(3')], 35.9 [C(2')], 71.5 [C(4)], 120.6 [C(7)], 123.6 [C(5)], 124.3 [C(6)], 125.9 [C(8)], 128.4 [C(4a)], 129.8 [C(8a)], 132.2, 133.1, 133.2, 139.6, 148.6 (CAr), 153.0 [C(2)]. Found (%): C, 51.69; H, 4.16; I, 27.06; N, 8.84. Calc. for C20H20IN3O2 (%): C, 52.07; H, 4.57; I, 27.51; N, 9.11. 10: yield 62%, mp 94–96 °C (Et2O). 1H NMR (CDCl3) d: 0.6 (t, 3H, Me, J 7.29 Hz), 1.3–1.9 (m, 2H, CH2), 2,27, 2.40 (s, 3H, Me), 4.2 (dd, 1H, H-2', J1 5.90 Hz, J2 11.34 Hz), 5.2 (s, 1H, H2C=), 5.5 (s, 1H, H2C=), 7.1–7.6 (m, 8H, Ar). 13C NMR (CDCl3) d: 10.1, 20.5, 25.1 (3Me), 25.0 (CH2), 73.6 [C(2')], 115.5 (H2C=C), 125.7, 126.0, 127.0, 128.1, 128.3, 129.1, 130.1, 134.6, 136.1, 142.7, 145.3, 155.0 (H2C=C, CAr, N–C=N). MS, m/z: 290 [M]+, 275 [M – Me]+, 261 [M – Et]+, 77 [M – Ph]+. Found (%): C, 82.31; H, 7.25; N, 9.21. Calc. for C12H17N (%); C, 82.72; H, 7.64; N, 9.65. Received: 28th June 2001; Com. 01/1816

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年代:2001

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