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Reactions of2-Oxo-2H-1-benzopyran-3-carbonitrile

 

作者: Conor N. O’Callaghan,  

 

期刊: Journal of Chemical Research, Synopses  (RSC Available online 1997)
卷期: Volume 0, issue 9  

页码: 312-313

 

ISSN:0308-2342

 

年代: 1997

 

DOI:10.1039/a701462g

 

出版商: RSC

 

数据来源: RSC

 

摘要:

OH CHO 1 O CN O 2 O N NH2 NC CN CN NH2 O N N NC CN NH2 CNCH2CN NH4OH 1 or 2 3 4 NH2 OH CN NH OH O NC O NH O O NC 9 11 H+ 2 CH3CO2NH4 CNCH2CO2R NH2 O CN OH CN N NH2 NH2 NC 8 10 CH3CO2NH4 NH2 NC CN H+ O N NH2 NH2 NC 12 NH O N NH2 NH2 NC 13 O 312 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 312–313 J. Chem. Research (M), 1997, 2101–2122 Reactions of 2-Oxo-2H-1-benzopyran-3-carbonitrile Conor N. O’Callaghan,* T. Brian H. McMurry, John E. O’Brien and Sylvia M. Draper University Chemical Laboratory, Trinity College, Dublin 2, Ireland Synthetic reactions of 2-oxo-2H-1-benzopyran-3-carbonitrile afford products which establish that partial or complete cleavage of the starting material occurs in the course of reaction.Benzopyran derivatives are useful starting materials for the preparation of polyheterocyclic compounds,2–4 but the products vary considerably according to the structure and reactivity of the parent benzopyran. The use in synthesis of the stable compound 2-oxo-2H-1-benzopyran-3-carbonitrile 2 (which is formed by reaction of salicylaldehyde 1 with alkyl cyanoacetates5) is now described.Some synthetic reactions of the bicyclic compound 2 have already been reported in the literature. Most of these reactions were carried out in the pre-NMR era; in some cases it was not possible to formulate the products, while in others the products were formulated incorrectly. It is now clear that the basic mistake was the assumption that, during reaction, the 2-oxo-2H-1-benzopyran structure remained essentially intact (as happens, for example, when 2-oxo-2H-1- benzopyran-3-carboxamide undergoes reaction4).In fact, our results show that the nitrile derivative 2 usually undergoes ring-opening (by fission of the 1,2 bond) and that fission of the 3,4-bond may also occur, resulting in cleavage of the molecule. This is well illustrated by the reaction of 2-oxo- 2H-1-benzopyran-3-carbonitrile 2 with malononitrile and ammonium acetate.A previous report states that this affords an inseparable mixture of (unformulated) products.6 The products formed are now identified as the tri- and tetra-cyclic compounds 3 and 4, both of which have been shown to be formed directly from the reaction of salicylaldehyde with malononitrile.2 The reaction of the bicyclic compound 2 with methyl cyanoacetate in the presence of ammonia or ammonium acetate affords the tricyclic product 11. (This product is also obtained from the reaction of 2 with ammonia or ammonium acetate alone, when the mechanism must involve disproportionation of 2.) Prior to purification of 11, when the crude product is first obtained, the 1H NMR spectrum shows that a monocyclic impurity is also present.This is presumed to be the pyridine derivative 9 but it is not isolable; in [2H6]dimethyl sulfoxide solution it slowly changes into the tricyclic product 11 (a change which takes place more rapidly in the presence of mineral acid).In the course of examining the reaction 2h9h11, we studied also the related reaction of ammonium acetate with the benzopyran derivative 8 (which represents the first isolable product formed by reaction of salicylaldehyde with malononitrile in 1:2 ratio). This reaction follows a similar pathway 8h10h12h13, but in this case it is possible to isolate the monocyclic pyridine intermediate 10. This is also converted, in the presence of acid, into a tricyclic product 13; presumably the imino group in the postulated intermediate 12 is hydrolysed during formation of 13.The reaction of 2 with 2-aminoprop-1-ene-1,1,4-tricarbonitrile 14 in the presence of ammonia has been reported to afford the simple addition compound 15,11 but the NMR spectrum is not reconcilable with the structure, and in fact the correct formulation of the product is 16. In a different type of reaction, the benzopyran 2 reacts with ketones and ammonium acetate to afford the bridged structure 20.Thus, with 3-oxobutanamide 17 (R=H, Rp=CONH2) and ammonium acetate, the amide derivative 20 (R=H, Rp=CONH2) is formed. In a related reaction, when the benzopyran 2 reacts with methyl acetoacetate and ammonium acetate, the main product is the ester derivative 20 (R=CO2Me, Rp=H). The molecular structure of this compound, as determined by X-ray diffraction, is shown in Fig. 1. This appears to be the first published example of an X-ray determination of a bridged structure of this general type.Crystal Structure Determination of 20 (R=CO2Me, Rp=H).·Data were collected on an Enraf-Nonius CAD-4 *To receive any correspondence.NC NH2 CN CN 14 2 + O O CN NC NH2 NC CN O O NC NH NC CN NH2 15 16 2 + RCH2COCH2R¢ O NH R¢CH2 R H CN O 20 17 J. CHEM. RESEARCH (S), 1997 313 diffractometer (Mo radiation, graphite monochromator, w–2y scans) at 20 °C. The crystal data and experimental parameters are given in Table 1. The final cell parameters were determined using the Celdim routine.It was not found necessary to apply decay or absorption corrections to the data. The data were reduced to give the number of unique reflections and those with |F|E4s|F| were used in structure solution and refinement. The structure was solved by automatic direct methods using SHELXS-86.15 The structure was refined by full-matrix least-squares analysis on F2 with SHELXL.16 The non-hydrogen atoms were refined anisotropically and all the hydrogen atoms were located from subsequent difference Fourier maps and refined with individual temperature factors to a final R value of 4.4%. Techniques used: IR, 1H NMR, 13C NMR, X-ray crystallography, elemental analysis References: 17 Appendix: Tables of atomic coordinates and equivalent isotropic displacement parameters, bond lengths and angles, anisotropic displacement parameters, and hydrogen coordinates and isotropic displacement parameters for 20 (R=CO2Me, Rp=H) Received, 3rd March 1997; Accepted, 3rd June 1997 Paper E/7/01462G References cited in this synopsis 2 C.N. O’Callaghan, T. B. H. McMurry and J. E. O’Brien, J. Chem. Soc., Perkin Trans. 1, 1995, 417. 3 C. N. O’Callaghan, T. B. H. McMurry, J. E. O’Brien, S. M. Draper and D. J. Wilcock, J. Chem. Soc., Perkin Trans. 1, 1996, 1067. 4 C. N. O’Callaghan, T. B. H. McMurry and J. E. O’Brien, J. Chem. Res., 1995, (S) 490; (M) 3001. 5 B. B. Dey and H. Dalal, J. Chem.Soc., 1923, 123, 3384. 6 H. Junek and F. Frosch, Z. Naturforsch., Teil B., 1971, 26, 1124. 11 H. Junek, Monatsh Chem., 1964, 95, 234. 15 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467. 16 G. M. Sheldrick, SHELXL 93, Program for Crystal Structure Refinement, University of G�ottingen, G�ottingen, 1993. Table 1 Crystal data and structure refinement for 20 (R=CO2Me, Rp=H) Empirical formula C15H14N2O4 Formula weight 286.28 Temperature 293(2) K Wavelength 0.71069 Å Crystal system monoclinic Space group P21/c Unit cell dimensions a=13.445(2) Å a=90° b=12.449(2) Å b=108.57° c=8.918(3) Å g=90° Volume 1415.0(5) Å Z 4 Density (calculated) 1.344 g cmµ3 Absorption coefficient 0.099 mmµ1 F(000) 600 Crystal size 0.3Å0.5Å0.4 mm Theta range for data collection 1.60–21.98° Index ranges µ13shs13, 0sks13, 0sls9 Reflections collected 1866 Independent reflections 1728 [R(int)=0.0189] Refinement method Full-matrix least-squares on F2 Data/restraints/parameters 1728/0/246 Goodness-of-fit on F2 1.219 Final R indices [Ia2s(()] R1=0.0444, wR2=0.1074 R indices (all data) R1=0.0600, wR2=0.1132 Largest diff. peak and hole 0.198 and µ0.205 e ŵ3 Fig. 1 Molecular structure of methyl 12-cyano-9-methyl-11-oxo- 8-oxa-10-azatricyclo[7.3.1.02,7]trideca-2,4,6-triene-13-carboxylate 20 (R=CO2Me, Rp=H), showing the crystallographic numbering sy

 



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