摘要:

The Synthesis and Preferred Conformation of Pyridoyl Urea and Analogous Derivatives: Preparation of a Folate Analogue Stefano Masiero,* Federico Fini, Giovanni Gottarelli* and Gian Piero Spada Dipartimento di Chimica Organica ``A. Mangini'', Universita! di Bologna, Via S. Donato 15, 40127 Bologna, Italy The synthesis of 2-pyridoyl urea and analogous derivatives is reported; NMR spectra show that the acylureas adopt an intramolecular H-bonded conformation. We are interested in pyridoyl urea and analogous derivatives as monocyclic models of guanine and pterine.1 A literature search revealed a scarcity of data on these unsubstituted acylurea derivatives and, in particular, a dearth of synthetic work.9a,b We have, therefore, tried a few straightforward synthetic pathways to easily obtain the desired derivatives from simple precursors (Scheme 1).The methyl ester gave the most encouraging results; speciRcally, when reacted with excess metallated urea (obtained in THF with KH) it gave the desired product in a 90% isolated yield.This synthetic procedure was extended to the obtainment of compounds 2�}6 and in all cases yields >60% of isolated products were obtained (Table 1) We decided to prepare the potentially biologically active folate analogue 14 with a pyridoyl urea in place of the pterine moiety. The synthetic pathway is described in Scheme 2. The 300 MHz 1H NMR spectrum of 2 in CDCl3 shows three di€erent signals (a, b and c), corresponding to three di€erent NH protons at 10, 8.3 and 5.3 ppm, respectively.The spectrum recorded in [2H6]DMSO at room temperature also displays three NH signals; however, signals b and c are much closer and at 60 8C they coalesce at ca. 7.5 ppm. J. Chem. Research (S), 1998, 634�}635 J. Chem. Research (M), 1998, 2736�}2753 Scheme 1 Scheme 2 Reagents: i, Fmoc-Cl in 10% Na2CO3/1,4-dioxane; ii, 2-chloro-4,6-dimethoxytriazine, N-methylmorpholine, L-glutamic acid dimethyl ester hydrochloride in CH2Cl2; iii, piperidine in CH2Cl2; iv, DIBAL-H in CH2Cl2; v, MeOH, CH(OCH3)3, PPTS; vi, KH, urea in THF; vii, H2O, H2SO4, silica; viii, L-glutamic acid dimethyl ester p-amino-benzoate, TFA, NaBH3CN in CH2Cl2; ix, 1 M NaOH/THF *To receive any correspondence. 634 J. CHEM. RESEARCH (S), 1998Hence, this molecule adopts the intramolecular H-bonded conformation 2b. This structure is stable and only in the competing DMSO solvent at high temperature does exchange of the bonded and free NH2 protons become fast on the NMR time scale.NMR spectra of derivatives 3±6 and 13 show a similar behaviour; thus, we think that intramolecularly H-bonded structures analogous to 2b are also the most stable for these derivatives. In vitro anti-cancer and anti-HIV screening of compounds 3±4 and 14 is in progress. We thank the University of Bologna (`Progetto d'Ateneo: Biomodulatori Organici') and C.N.R. (Rome) for ®nancial support for this work. Techniques used: 1H and 13C NMR, IR, mass spectrometry and circular dichroism References: 11 Schemes: 2 Table: 1 Fig. 1: The G-quartet Fig. 2: Species composed of two or more G-quartets in the presence of Ká Fig. 3: 1H NMR spectra of 2 Received, 18th May 1998; Accepted, 15th June 1998 Paper E/8/03698E References cited in this synopsis 1 G. Gottarelli, G. P. Spada and A. Garbesi, in Comprehensive Supramolecular Chemistry. Vol. 9, Templating, Self-Assembly and Self-Organization, eds. J.-P. Sauvage and M. W. Hosseini, Pergamon Press, Oxford, 1996, ch. 13. 9 (a) T. J. Ward and J. C. White, (Eur. Pat.) Chem. Abstr., 1989, 112, 118 671d; (b) J. W. Hani®n, Jr., R. A. Capuzzi and E. Cohen, (US Pat.) Chem. Abstr., 1967, 67, 116 893f. Table 1 Yields of derivatives 2±6 Derivative Formula Yield (%) 2 90 3 78 4 60 5 62 6 94 J. CHEM. RESEARCH (S), 19

ISSN:0308-2342    

DOI:10.1039/a803698e

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Synthesis of Analogues of Methyl Jasmonate using the Formation of Cyclopentenones from Alkyne(hexacarbonyl)dicobalt Complexes Carol J. Clements, Denis Dumoulin, David R. Hamilton, Milan Hudecek, William J. Kerr,* Matthias Kiefer, Paul H. Moran and Peter L. Pauson* Department of Pure and Applied Chemistry, University of Strathclyde, Cathedral Street, Glasgow G1 1XL, Scotland A range of mono- and bicyclic cyclopentenone and 3-oxocyclopentaneacetic acid derivatives have been made for biological comparison with jasmonates.Jasmonic acid as the free acid or its methyl ester 1a is very widely distributed in the plant kingdom and has various important growth regulatory functions.1 Apart from poten- tial uses of methyl jasmonate based on, for example, its anti- transpirant e€ect, its inhibition of seed germination and its control of fruit ripening, recent attention has been focussed on its ability to inhibit sprouting of potatoes2 and its ability to act as an elicitor of phytoalexins4 and hence, inter alia, to enhance taxol production in yew cell cultures.5 While the full range of action may be restricted to methyl jasmonate (1a) and very close analogues (including molecules that bio- degrade to jasmonic acid) some of the compounds described herein have shown, in tests of plant growth regulatory properties, that substances di€ering widely in structure from jasmonate may show selected e€ects to a high degree.The active compounds include some of the cyclopentenones of types 2 and 3, which were originally made as intermediates that are convertible into jasmonate analogues.The cyclopentenones were made from alkyne(hexa- carbonyl)dicobalt complexes and appropriate alkenes by the Khand reaction. Thus, for example, compounds 3c�}h are formed according to Scheme 1. Most Khand reactions were conducted with trimethylamine N-oxide as promoter, but the use of tributylphosphine oxide15 and of Smit's solid state adsorption technique16 (for intramolecular Khand reactions) is also exempliRed.Many of the compounds made have a pentyl side-chain at C-2, i.e. they are analogues of the biologically active methyl dihydrojasmonate (1b), chosen because they can be derived from the readily available hept- 1-yne, whereas the corresponding intermediate to provide the unsaturated side-chain of methyl jasmonate (1a) and of cis-jasmone (4) is (Z)-hept-4-en-1-yne, which requires a multistep synthesis.7 The aryl analogues were included when it was found that replacement of a pentyl by a phenyl side chain led to signiR- cant retention of biological activity.The p-methoxy-(3e), chloro-(3g) and �Puoro-(3h) compounds were obtained from the corresponding arylacetylenes, a new route involving dibromo-oleRnation of the aldehyde (Scheme 2) being used to make p-chlorophenylethyne. The p-acetyl derivative (3f ) was synthesised by Friedel�}Crafts acetylation of the phenyl compound (3d).The ketene silyl acetal Me3SiCH.C(OMe)OSiMe3 18 was the preferred reagent for the Michael-type reaction to add the acetate side-chain, for example, to cyclopentenone derivatives (3) to give oxo esters such as (5) and (6), but had to be replaced by the less sterically demanding CH2.C(OMe)OSiMe2But19 to make possible such addition to the fully-substituted double bond of the enone (7) to yield 9 with the acetate side-chain in the angular position. The epoxidation of methyl jasmonate with m-chloroper- benzoic acid is also described.J. Chem. Research (S), 1998, 636�}637 J. Chem. Research (M), 1998, 2658�}2677 *To receive any correspondence. 636 J. CHEM. RESEARCH (S), 1998Techniques used: 1H and 13C NMR References: 27 Schemes: 3 Table 1: Khand reactions Received, 8th June 1998; Accepted, 25th June 1998 Paper E/8/04323J References cited in this synopsis 1 For recent reviews see: B. Parthier, J. Plant Growth Regul., 1990, 9, 57; G. Sembdner and B.Parthier, Annu. Rev. Plant Physiol. Plant Mol. Biol., 1991, 44, 569; B. Parthier, Bot. Acta, 1991, 104, 446. 2 E. C. Lulai, P. H. Orr and M. T. Glynn, US Pat. 5436226 (25 July 1995). 4 (a) E. E. Farmer and C. A. Ryan, Proc. Natl. Acad. Sci. U.S.A., 1990, 87, 7713; (b) H. Gundlach, M. J. MuÈ ller, T. M. Kutchan and M. H. Zenk, Proc. Natl. Acad. Sci. U.S.A., 1992, 89, 2389; (c) S. Blechert, W. Brodschelm, S. HoÈ lder, L. Kammerer, T. M. Kutchan, M. J. Mueller, Z.-Q. Xia and M.H. Zenk, Proc. Natl. Acad. Sci. U.S.A., 1995, 92, 4099; (d) H. T. Alborn, T. C. J. Turlings, T. H. Jones, G. Stenhagen, J. H. Loughrin and J. H. Tumlinson, Science, 1997, 276, 945; (e) M. McConn, R. A. Creelman, E. Bell, J. E. Mullet and J. Browse, Proc. Natl. Acad. Sci. U.S.A., 1997, 94, 5473; ( f ) S. Blechert, C. Bockelmann, O. BruÈ mmer, M. FuÈ ûlein, H. Gundlach, G. Haider, S. HoÈ lder, T. M. Kutchan, E. W. Weiler and M. H. Zenk, J. Chem. Soc., Perkin Trans. 1, 1997, 3549. 5 (a) N. Mirjalili and J. C. Linden, Biotechnol. Prog., 1996, 12, 110; (b) Y. Yukimune, H. Tabata, Y. Higashi and Y. Hara, Nat. Biotechnol., 1996, 14, 2129. 7 D. C. Billington, P. Bladon, I. M. Helps, P. L. Pauson, W. Thomson and D. Willison, J. Chem. Res., 1988, (S) 326; (M) 2601. 15 D. C. Billington, I. M. Helps, P. L. Pauson, W. Thomson and D. Willison, J. Organomet. Chem., 1988, 354, 233. 16 W. A. Smit, S. O. Simonian, V. A. Tarasov, G. S. Mikaelian, A. S. Gybin, I. I. Ibragimov, R. Caple, D. Froen and A. Kreager, Synlett, 1989, 472. 18 I. Matsuda, S. Murata and Y. Izumi, J. Org. Chem., 1980, 45, 237. 19 Y. Kita, J. Segawa, J. Yasuda and Y. Tamura, J. Chem. Soc., Perkin Trans. 1, 1982, 1099. Scheme 1 Scheme 2 J. CHEM. RESEARCH (S)

ISSN:0308-2342    

DOI:10.1039/a804323j

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Studies on the Synthesis of Highly Substituted Naphthol: Preparation of 6-Hydroxy-5,7-dimethoxy- 2-naphthoic Acid, Isolated from Ulmus Thomasii Claudio Fuganti and Stefano Serra* Dipartimento di Chimica del Politecnico, Centro CNR per la Chimica delle Sostanze Organiche Naturali, Via Mancinelli 7, 20131 Milano, Italy An improvement to a known procedure, affording substituted 4-hydroxy-2-naphthoic acid derivatives from aromatic aldehydes, is described and its general applicability shown through the preparation of a natural naphthalene derivative isolated from Ulmus thomasii.Recently,1 we have developed a benzoannulation2 procedure in which divinylketene3 derivatives are easily generated at room temperature from 3-methoxycarbonyl-6-arylhexa-3,5- dienoic acid, using triethylamine/ethyl chloroformate as activating agent, to give 4-aryl-3-hydroxybenzoic esters in high yields. A further study4 has shown that a double bond of the heteraromatic ring can function as the g,d-double bond of the dienoic system. Accordingly we decided to investigate the general applicability of the mixed anhydride/ Et3N method for the synthesis of the naphthol derivatives starting from 3-alkoxycarbonyl-4-arylbuten-3-oic acid.Our procedure works under mild conditions, a€ording 4-hydroxy-2-naphthoic acid derivatives. In a typical exper- iment (Scheme 2) 3-alkoxycarbonyl-4-aryl-3-butenoic acid 6 or 7 was treated at room temperature with 2.1 equiv. of a suitable activating agent (ethyl chloroformate or tri�Puoroa- cetic anhydride) followed by the dropwise addition of an excess (3�}4 equiv.) of triethylamine.The thus formed mixed anhydride is unstable in base and can be isolated only in a deRciency of triethylamine. As mentioned above, the excess of base induces the conversion of 6 or 7 into a vinylketene intermediate which cyclizes through a 1,6-electrocyclic reaction to give 8 or 9 (or its carboxyethyl�}tri�Puoroacetyl derivative).The overall process is very fast (about 15 min at 0�}20 8C) and the mild conditions used tolerate a wide pattern of substituents on the aromatic ring. The starting mono acid�}mono ester was obtained through a classical Stobbe condensation or by using triphenyl(a-carbethoxy-b-carboxy- ethyl)phosphonium betaine when the substituents on the aromatic ring are labile towards the strong basic conditions of the direct condensation. The cyclization step was performed in THF solution and the crude product, which is a phenolic derivative, was isolated at the phenol-ester 8 or 9 upon rapid treatment with alcoholic NaOH (2 equiv.) followed by acidiRcation.If tri�Puoroacetic anhydride is the activating agent, reductive deprotection with NaBH4 is also possible and becomes the method of choice when the substituent group is labile in basic hydrolytic conditions. The yields of products puriRed upon crystallization or chromatography column (Table 1) are very good (80�}90% J.Chem. Research (S), 1998, 638�}639 J. Chem. Research (M), 1998, 2769�}2782 Scheme 2 Table 1 Isolated yields for the condensation reaction of aldehydes 5a�}f, affording 6a�}f, and for the cyclization reaction of acids 6a�}f, 7a�}b to esters 8a�}f, 9a�}b Aldehyde R Acid R' R0 Yield (%)a Ester Cycliz. method Yield (%) 5a H 6a Et H 85B 8a ClCO2Et/Et3N 57 5b 2,3,4-OMe 6b Me H 69A 8b ClCO2Et/Et3N 91 5c 3,5-OMe 4-OBz 6c Me H 59A 8c ClCO2Et/Et3N 84 5d p-Cl 6d Et H 78B 8d ClCO2Et/Et3N 50 5d p-Cl 6d Et H 78B 8d (CF3CO)2O/Et3N 80 5d p-Cl 7a Et Me 55B,b 9a (CF3CO)2O/Et3N 83 5d p-Cl 7b Et CH2CHCH2 58B,b 9b (CF3CO)2O/Et3N 85 5e p-CN 6e Et H 71B 8e (CF3CO)2O/Et3N 71 5f p-MeS 6f Et H 70B 8f ClCO2Et/Et3N 61 aA, B are the condensation methods.bThe yield includes both the condensation and alkylation step. *To receive any correspondence. 638 J. CHEM. RESEARCH (S), 1998in the preparation of 8b, 8c) when the substituent group Ractivates the aromatic ring towards the electrophilic attackof the intermediate ketene.If ethyl chloroformate is used and the starting acid lacksan activating group at the meta position or the aromaticring bears an electron-attracting substituent, the yields dropto 50¡Ó60% (8a, 8d¡Ó8f ) and a complementary amount ofthe ethyl ester of acids 6 is observed in the reaction mixture.We assume that ethanol, derived from the decompositionof mixed anhydride, reacts with the surviving ketene togive the ethyl ester.According to our scheme the sameprocedure, performed by using (CF3CO)2O and by prolong-ing the reaction time (0.5¡Ó3 h), gives good yields of cyclizedproducts (8d, 8e, 9a, 9b).Examination of the substitution pattern of the monoacids¡Ómono esters 6, 7 shows the exibility of the syntheticapproach: methoxy, halo, cyano allyl and methylthio groupsare unaected to give the related naphthols 8, 9.Recently new, mild, regioselective syntheses of sub-stituted naphthalenes have received signicant attention, es-pecially for the preparation of natural products.To investi-gate the validity of our method in this eld we prepared6-hydroxy-5,7-dimethoxy-2-naphthoic acid 16 (Scheme 3), anaphthalene derivative isolated12 from Ulmus thomasii. Ourprocedure compares favourably with the previous prep-aration,13 in which the key step was a ring closure througha classical Friedel¡ÓCrafts reaction.Thus, starting from commercially available syringaldehyde13, we synthesized the mono acid¡Ómono ester 6c througha Stobbe condensation between the protected phenol 5cand dimethyl succinate.The latter was cyclized using theClCOOEt/Et3N system and the product 8c was isolated asa phenol-ester derivative upon basis (NaOH, 2, equiv.) treat-ment followed by acidication (HCl 5%).The hydroxy group at position 4 of 8c was easilyremoved, via hydrogenolytic treatment of 14. The phenyl-tetrazolyl derivative 14, in a one-pot procedure, gives 15in 85% overall yield.The methyl ester 15 was convertedinto the acid 16, whose spectroscopic data are identical tothose reported in the literature.12 The method has prepara-tive signicance because the yield in the cyclization step ishigh (80% versus 30% for the classical procedure) and thedehydrogenation of tetralin is avoided.Moreover, treatment of 3-alkoxycarbonyl-4-arylbut-3-enoic acids 6 with 2 equiv. of lithium diisopropylamide at£¾78 8C aords the related dianions which can be easilyalkylated at the a-position using 1 equiv.of alkyl orallyl halide (Scheme 2). Cyclization of the resulting acid (7)gives 4-hydroxy-3-alkyl(allyl)-2-naphthoic acid derivatives 9in good yields. We have used this approach to build upnaphthofurans using a procedure described by Kishi et al.16The synthesis of this kind of compound is shown throughthe preparation of compound 17 (Scheme 4) which wasobtained in good yields upon warming a solution of allyl-phenol 9b in presence of a palladium salt.Thus, these results show that the mixed anhydride benzo-annulation oers the following advantages: (i) the basiccatalysis promoting the cyclization step is very mild andallows one to obtain a wide pattern of substituents on thenaphthalene ring; (ii) substituted benzaldehydes which arethe starting materials, are easily available; (iii) alkylationof the dianion of 3-alkoxycarbonyl-4-arylbut-3-enoic acidaords a useful method for the regioselective synthesis of4-hydroxy-3-alkyl-2-naphthoic acid derivatives.Techniques used: 1H NMR, IR and mass spectrometryReferences: 16Schemes: 4Table 1: Isolated yields for the condensation reactions of aldehydes5a¡Óf aording 6a¡Óf, and for the cyclization reaction of acids 6a¡Óf toesters 8a¡Óf, 9a,bTable 2: Isolated yields for the condensation reaction of aldehydes10a¡Óc aording 11a¡Óc, and for the cyclization reaction of acids11a¡Óc to give esters 12a¡ÓcReceived, 15th May 1998; Accepted, 23rd June 1998Paper E/8/03651IReferences cited in this synopsis1 E.Brenna, C. Fuganti, V. Perozzo and S. Serra, Tetrahedron,1997, 53, 15029.2 For a review on the aromatic annulation reaction see:P. Bameld and P. F. Gordon, Chem. Soc. Rev., 1984, 13, 441;for more recent examples in the R. Katritzky, G. Zhang and L. Xie, J. Org. Chem., 1997, 62,721; A. R. Katritzky, C. N. Fali and J. Li, J. Org. Chem., 1997,62, 8205.3 For a previous annulation method involving dienylketenes see:P. Turnbull and H. W. Moore, J. Org. Chem., 1995, 60, 644 andreferences cited therein; S. Karady, J. S. Amato, R. A. Reamerand L. M. Weinstock, Tetrahedron Lett., 1996, 37, 8277.4 E. Brenna, C. Fuganti and S. Serra, Tetrahedron, 1998, 54, 1585.12 F. D. Hostettler and M. K. Seikel, Tetrahedron, 1969, 25, 2325;C. Loung Chen and F. D. Hostettler, Tetrahedron, 1969, 25,3223; J. L. Charlton and K. Ann Lee, Tetrahedron Lett., 1997,38, 7311.13 M. Lehrer and R. Stevenson, J. Chem. Soc., Perkin Trans. 1,1974, 1165.16 B. A. Pearlman, J. M. McNamara, I. Hasan, S. Hatakeyama,H. Sekizaki and Y. Kishi, J. Am. Chem. Soc., 1981, 103, 4248.Scheme 3 Reagents and conditions: i, B2Cl, DMF, Na2CO3;ii, dimethylsuccinate, MeONa/MeOH; iii, ClCO2Et/Et3N;iv, 5-Cl-1Ph-1H-tetrazole, Na2CO3, DMF; v, H2, Pd/C; vi, NaOH,then H3OScheme 4J. CHEM. RESEARCH (S), 1998 639

ISSN:0308-2342    

DOI:10.1039/a803651i

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Montmorillonite Clays Catalysis. Part 12.1An Efficient and Practical Procedure for Synthesisof Diacetals from 2,2-Bis(hydroxymethyl)propane-1,3-diol with Carbonyl Compounds$Zhan-Hui Zhang,a,b Tong-Shuang Li,*a Tong-Shou Jina and Ji-Tai LiaaDepartment of Chemistry, Hebei University, Baoding 071002, Hebei Province, P.R. ChinabDepartment of Chemistry, Hebei Teachers University, Shijiazhuang 050091, Hebei Province,P.R. ChinaPreparation of diacetals from 2,2-bis(hydroxymethyl)propane-1,3-diol with aldehydes and ketones is catalysed bymontmorillonite clays in refluxing benzene or toluene in good to excellent yield.Pentaerythritol acetals are applied as plasticizers and vulca-nizers of various polymeric materials, as raw materials forproduction of valuable resins and lacquers, as physiologi-cally active substances2 and as defoamers for washingsolution containing anionic surfactants.3 They can be usedas potential protective groups for aldehydes and ketones aswell as important derivatives of carbonyl compounds sincemost are crystalline substances and have sharp meltingpoints.Several publications have described the preparationof pentaerythritol diacetals under acidic conditions.4Protic acids (hydrochloric acid,5 sulfuric acid,3,6,7 and p-toluenesulfonic acid5,8,9) and Lewis acids (zinc chloride,10anhydrous copper sulfate11) have been employed as cata-lysts. However, these methods have not been entirelysatisfactory, owing to problems of corrosion, tedious work-up, environmental pollution and non-recoverable catalysts.Consequently, there is a demand for environmentallyfriendly acid catalysts to synthesize pentaerythritol diacetalsunder mild conditions.Cation exchanger KU-22 and12-tungstophosphoric acid12 have been used as catalysts forthe condensation of 2,2-bis(hydroxymethyl)propane-1,3-diolwith aldehydes and ketones. More recently, microwaveirradiation was applied to accelerate this reaction.13Clay minerals are known to catalyse a variety of organicreactions in which the catalyst acts as a solid Lewis acid orBrnsted acid.14 Recently, we have developed ecientand convenient procedures for preparation15 and cleavage16of 1,3-dioxolanes catalysed by montmorillonite K-10.As apart of ongoing work on montmorillonite clay catalysis,17we now describe a direct condensation of aldehydes andketones with 2,2-bis(hydroxymethyl)propane-1,3-diol cata-lysed by montmorillonites K-10 and KSF.As summarized in Table 1, several aldehydes andketones in the presence of montmorillonites K-10 or KSFwere heated with 2,2-bis(hydroxymethyl)propane-1,3-diol inreuxing benzene or toluene, resulting in the correspondingdiacetals in good to excellent yields.K-10 worked betterthan KSF in terms of reaction time and yield. This may bedue to it having a greater surface area (220¡Ó270 m2 g£¾1)than that of KSF (20¡Ó40 m2 g£¾1). The reaction proceedscleanly and the work-up is simple, involving only ltrationof the catalyst and removal of solvent to obtain the productin high purity.The reaction rate is markedly dependent on temperature.The reaction proceeded much more slowly in reuxingbenzene than in toluene.For example, complete conversionof 3-chlorobenzaldehyde (1i) into the corresponding diacetal(3i) needed 0.8 h in reuxing toluene, but 1.5 h in reuxingbenzene under catalysis by montmorillonite K-10. Ketonesshow less reactivity than aldehydes for this reaction, forexample dibenzal pentaerythritol (3f ) was obtained in quan-titative yield (98%) from reuxing benzene for 1 h whereasacetophenone (1s) provided 89% yield of product fromreuxing toluene for 8 h in the presence of montmorilloniteK-10.It is worth noting that when 4-hydroxybenzaldehyde(1l) and 4-(dimethylamino)benzaldehyde (1n) were treatedwith 2,2-bis(hydroxymethyl)propane-1,3-diol in the presenceof K-10 the reactions took longer (>8 h) even under reux-ing in toluene.The explanation, we propose, is that thestrong donor groups hydroxy and dimethylamino reducethe reactivity.The catalysts are easily regenerated by washing withethanol followed by drying at 120 8C for 4 h. The catalystcould be reused three times for the synthesis of penta-erythritol diacetal 3f without signicant loss of activity.In conclusion, the present procedure appears to be e-cient for aldehydes and ketones. The operational simplicity,use of inexpensive, non-corrosive and reusable catalysts andhigh yields can make it a useful and attractive alternative tothe currently available methods.ExperimentalMelting points are uncorrected. 1H NMR spectra were deter-mined on a Varian VXR-300 S (300 MHz) spectrometer usingCDCl3 as solvent and tetramethylsilane (TMS) as internal reference,IR spectra on a FTS-40 spectrometer. Montmorillonite K-10 andKSF were purchased from Aldrich and dried at 120 8C for 2 h priorto use.General Procedure for Preparation of Diacetals.A mixtureof carbonyl compound (1, 3.00 mmol), 2,2-bis(hydroxymethyl)-propane-1,3-diol (2, 1.80 mmol) and montmorillonite K-10 or KSF(300 mg) in benzene or toluene (20 ml) was stirred at reuxing tem-perature for 0.6¡Ó12 h (Table 1) using a Dean¡ÓStark apparatusfor water removal.The progress of the reaction was monitoredby TLC. After cooling, the catalyst was ltered o and washedwith CH2Cl2 (5 ml2). Evaporation of the solvent under reducedpressure aorded the crude product.This was puried by columnchromatography on silica gel [light petroleum (bp 60¡Ó90 8C)¡Ódichloromethane as eluent] or recrystallised to give diacetals 3, yield70¡Ó98% (Table 1).J. Chem. Research (S),1998, 640¡Ó641$Scheme 1$This is a Short Paper as dened in the Instructions for Authors,Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there-fore no corresponding material in J. Chem. Research (M).*To receive any correspondence.640 J. CHEM. RESEARCH (S), 1998Selected spectral data.DFor 3c: ~max/cm¡¦1 2910, 2862, 1600, 1460, 1390, 1050, 805; H 2.346 (6 H, s, 2CH3), 3.638 (2 H, d, J 11.7, 2Hax), 3.789¡À3.848 (4 H, m, 4Heq), 4.583 (2 H, d, J 11.7, 2Hax), 5.424 (2 H, s, 2Ar CH), 7.181 (4 H, d, J 8.0, 23',5' Ar H), 7.370 (4 H, d, J 8.0 Hz, 22',6' Ar H). For 3i: ~max/cm¡¦1 2986, 2856, 1577, 1479, 1381, 1074, 966, 702; H 3.656 (2 H, d, J 11.4, 2Hax), 3.840 (4 H, d, J 11.4, 4Heq), 4.829 (2 H, d, J 11.4 Hz, 2Hax), 5.432 (2 H, s, 2Ar CH), 7.307¡À7.381 (6 H, m, Ar H), 7.503 (2 H, s, 22' Ar H).For 3k: ~max/cm¡¦1 3400, 2860, 2362, 1600, 1500, 1080, 780; H 3.703 (2 H, d, J 11.8, 2Hax), 3.879¡À3.927 (4 H, m, 4Heq), 4.847 (2 H, d, J 11.8 Hz, 2Hax), 5.655 (2 H, s, 2Ar CH), 6.872¡À7.284 (8 H, m, Ar H), 7.565 (2 H, br s, 2OH). For 3m: ~max/cm¡¦1 3407, 2858, 1604, 1522, 1383, 1163, 1075, 1027, 864, 780; H 3.650 (2 H, d, J 11.5, 2Hax), 3.795¡À3.863 (4 H, m, 4Heq), 3.916 (6 H, s, 2OCH3), 4.868 (2 H, d, J 11.5, 2Hax), 5.402 (2 H, s, 2Ar CH), 5.667 (2 H, br s, 2OH), 6.910 (2 H, d, J 8.2, 25' Ar H), 6.970 (2 H, dd, J 8.2, 1.5, 26' Ar H), 7.033 (2 H, s, 22' Ar H).For 3r: ~max/cm¡¦1 2970, 2865, 1470, 1380, 1160, 1075; H 0.880 [6 H, t, J 6.5, 2(CH2)5CH3], 1.28 (16 H, m, 8CH2), 1.353 (6 H, s, 2CH3), 1.662 (4 H, t, J 7.9 Hz, 2CH2), 3.712¡À3.881 (8 H, m, 4CH2O). For 3s: ~max/cm¡¦1 2980, 2900, 1470, 1380, 1250, 1175, 890, 704; H 1.502 (6 H, s, 2CH3), 3.150 (2 H, dd, J 11.1, 2.4, 2Heq), 3.248 (2 H, d, J 11.1, 2Hax), 3.631 (2 H, d, J 11.7, 2Hax), 4.474 (2 H, dd, J 11.7, 2.4 Hz, 2Heq), 7.313¡À7.425 (10 H, m, Ph H).For 3t: ~max/cm¡¦1 2990, 2855, 1600, 1480, 1075, 750, 702; H 2.878 (8 H, s, 4PhCH2), 3.589 (8 H, s, 4CH2O), 7.142¡À7.322 (20 H, m, Ph H). For 3u: ~max/cm¡¦1 2960, 2860, 1610, 1500, 1450, 1100, 780; H 3.879 (8 H, s, 4CH2O), 7.256¡À7.503 (20 H, m, Ph H). The project was supported by NSFC(29572039), Natural Science Foundation of Hebei Province (297065) and Science and Technology Commission of Hebei Province. Received, 23rd April 1998; Accepted, 17th June 1998 Paper E/8/03046D References 1 Part 11, Z.-H.Zhang, T.-S. Li, F. Yang and C.-G. Fu, Synth. Commun., 1998, 28, in the press. 2 T. N. Shakhtakhtinskii and L. V. Andreev, Dokl. Akad. Nauk Az. SSR, 1962, 18, 17 (Chem. Abstr., 1963, 59, 3762 g). 3 J. Perner, K. Stork, F. Merger and K. Oppenlaender, Ger. O€en, 1978, 2707875 (Chem. Abstr., 1978, 89, 181503x). 4 S. F. Marrian, Chem. Rev., 1948, 43, 149. 5 D. Callejas, M. Echemique and H. Seeboth, Rev. Cubana Quim., 1988, 4, 73 (Chem. Abstr., 1989, 111, 77927a). 6 J. Read, J. Chem. Soc., 1912, 101, 2090. 7 N. P. Klyushnik, Ukr. Khim. Zh., 1964, 30, 965 (Chem. Abstr., 1965, 62, 2717a). 8 E. Bograchov, J. Am. Chem. Soc., 1950, 72, 2268. 9 V. G. Mkhitaryan, J. Gen. Chem., 1939, 9, 1923. 10 H. J. Backer and H. B. Schurink, Recl. Trav. Chim. Pays-Bas, 1931, 50, 1066. 11 L.Orthner, Ber. Bunsenges. Phys. Chem., 1928, 61B, 116. 12 X. Chen, Y.-T. Xu and C.-X. Jin, Hecheng Huaxue, 1997, 5, 212. 13 C.-D. Wang, X.-Z. Shi and R.-J. Xie, Synth. Commun., 1997, 27, 2517. 14 For recent reviews, see: P. Laszlo, Acc. Chem. Res., 1986, 19, 121; A. Cornelis and P. Laszlo, Synlett, 1994, 155; M. Balogh and P. Laszlo, Organic Chemistry Using Clays, Springer, New York, 1993. 15 T.-S. Li, S.-H. Li, J.-T. Li and H.-Z. Li, J. Chem. Res. (S), 1997, 26. 16 T.-S. Li and S.-H.Li, Synth. Commun., 1997, 27, 2299. 17 Z.-H. Zhang, T.-S. Li and C.-G. Fu, J. Chem. Res. (S), 1997, 174; T.-S. Li, Z.-H. Zhang and C.-G. Fu, Tetrahedron Lett., 1997, 38, 3285; A.-X. Li, T.-S. Li and T.-H. Ding, Chem. Commun., 1997, 1389. 18 D. Radulescu and I. Tanasescu, Bull. Soc. Stiinte Cluj, 1922, 1, 192. Table 1 Preparation of diacetals catalysed by montmorillonite clays mp( 8C) Substrate Catalyst Solvent t/h Yield (%)a Found Reported n-C6H13CHO (1a) K-10 Benzene 1 93 62¡À63 636 n-C9H19CHO (1b) K-10 Benzene 1 95 75¡À76 77¡À7813 KSF Benzene 3 93 4-MeC6H4CHO (1c) K-10 Benzene 1 92 211¡À213 KSF Benzene 5 88 4-MeOC6H4CHO (1d) K-10 Benzene 1.5 90 182¡À184 1776 KSF Benzene 6 85 3,4-(OCH2O)C6H3CHO (1e) K-10 Benzene 1.5 92 192¡À193 1886 C6H5CHO (1f) K-10 Benzene 0.6 98 155¡À156 155¡À15613 KSF Benzene 2.5 93 2-O2NC6H4CHO (1g) K-10 Benzene 2.5 93 164¡À165 163¡À16413 3-O2NC6H4CHO (1h) K-10 Toluene 1 92 185¡À186 1856 3-ClC6H4CHO (1i) K-10 Benzene 1.5 95 121¡À122 K-10 Toluene 0.8 94 4-ClC6H4CHO (1j) K-10 Benzene 2 92 200¡À201 197¡À19813 2-HOC6H4CHO (1k) K-10 Benzene 3 90 160¡À161 K-10 Toluene 1.5 91 4-HOC6H4CHO (1l) K-10 Toluene 10 70b 110¡À112 109¡À11013 3-MeO-4-HOC6H3CHO (1m) K-10 Benzene 2.5 95 170¡À171 4-Me2NC6H4CHO (1n) K-10 Benzene 6 89b 222¡À224 22318 K-10 Toluene 8 94 E-C6H5CH.CHCHO (1o) K-10 Benzene 3 93 188¡À189 1956 2-Furaldehyde (1p) K-10 Benzene 3 89 159¡À160 158¡À15913 KSF Benzene 7 87 Cyclohexanone (1q) K-10 Toluene 3 90 113¡À114 112¡À1137 KSF Toluene 6 89 CH3(CH2)5COCH3 (1r) K-10 Toluene 4 90 44¡À45 C6H5COCH3 (1s) K-10 Toluene 8 89 147¡À148 (C6H5CH2)2CO (1t) K-10 Toluene 8 91 166¡À167 (C6H5)2CO (1u) K-10 Toluene 12 97b 163¡À164 aYield refers to isolated pure products.bNet yield, conversion rate of 1l �� 33%; conversion rate of 1n �� 43%; conversion rate of 1u �� 79%. J. CHEM. RESEARCH (

ISSN:0308-2342    

DOI:10.1039/a803046d

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Sequential Transformation of Diethyl Phosphite.A Convenient Synthesis of Substituted(E)-3-Alkoxycarbonyl-b,g-unsaturated Esters$Yanchang Shen* and Zenghong ZhangShanghai Institute of Organic Chemistry, Academia Sinica, 354 Fenglin Lu, Shanghai 200032,ChinaThe sequential reaction of diethyl phosphite with sodium alkoxide, dimethyl maleate and aldehydes affords substituted(E)-3-alkoxycarbonyl-,-unsaturated esters in 63¡Ó73% yields.Recently, 3-alkoxycarbonyl-b,g-unsaturated esters haveattracted much attention since they are useful intermediatesfor the synthesis of substituted tetrahydrofurans which areessential components in many classes of naturally occurringbioactive compounds.1,2 Examples are nucleosides, poly-ether antibiotics, insect pheromones, plant lignans andmarine toxins.2 The earlier method for the preparation of3-alkoxycarbonyl-b,g-unsaturated esters involves Stobbecondensation3 which gives variable yields of the productscontaminated with byproducts.The Wittig and Horner¡ÓWadsworth¡ÓEmmons reactions were also applied to thesynthesis of the title compounds4,5 but their reagents requireprior preparation. Very recently a one-pot three-componentsynthesis of the title compounds has been reported.6Therefore to develop an eective method for their prep-aration would be valuable.Sequential transformations have attracted much interestin recent years because they provide a simple and eciententry to complex compounds by including two or moretransformations in a single operation to increase the com-plexity of substrate starting from commercially available,relatively simple precursors.7 In our continuing investigationof the application of sequential transformation of phos-phonates in organic synthesis8 we report the sequentialtransformation of phosphite and its application to the syn-thesis of substituted (E)-3-alkoxycarbonyl-b,g-unsaturatedesters (Scheme 1).Diethyl sodium phosphite, generated from diethyl phos-phite and sodium alkoxide, reacted with dimethyl maleateto give the phosphoryl-stabilized carbanion 3.Without iso-lation, 3 reacted with aldehydes giving 3-alkoxycarbonyl-b,g-unsaturated esters 4 in good yields. The results aresummarized in Table 1.The reaction is of wide scope since the R group may bealkyl, aryl and heterocyclic. it is noted that when sodiumethoxide was used as a base in ethyl alcohol, the diethyldiester was obtained exclusively since ester exchange hadoccurred.Thus, the sequential transformation of diethyl phosphiteprovides a convenient synthesis of the title compoundsunder mild conditions to give the E-isomer.ExperimentalAll boiling points are uncorrected with the oven temperature (ot)given.The IR spectra of products were obtained as lms on aPerkin-Elmer 983 spectrometer. 1H NMR spectra were recorded ona Bruker AM-300 (300 MHz) spectrometer (d values in ppm fromtetramethylsilane, in CDCl3, J values are given in Hz).Mass spectrawere measured on a Finnigan GC¡ÓMS-4021 mass spectrometer.General Procedure for the Synthesis of 3-alkoxy-,-unsaturated4.Sodium alkoxide or NaH (2 mmol) was added with stirring to asolution of diethyl phosphite (2 mmol) in absolute alcohol (10 ml) at20 8C under nitrogen. The reaction mixture was stirred for 0.5 h at20 8C and dimethyl maleate (0.29 g, 2 mmol) was slowly added. Themixture was stirred for 2 h and the aldehyde (2 mmol) was added.After addition the mixture was stirred for further 3 h and saturatedaqueous NH4Cl solution (2 ml) was added.The reaction mixturewas extracted with diethyl ether (320 ml). The combined organiclayer was washed with brine (20 ml) and dried over anhydrousNa2SO4. Evaporation of the solvent gave a residue which waspuried by ash chromatography on silica gel eluting with lightpetroleum (bp 60¡Ó90 8C)¡Óethyl acetate (20:1) to give the product 4.Ethyl (E)-4-(4-chlorophenyl )-3-ethoxycarbonylbut-3-enoate 4a.Yield, 70%.Bp 182 8C at 1 mmHg; (lit.,5 bp 135¡Ó138 8C at 0.2Torr); max/cm£¾1; 2980, 1730, 1640, 1450, 1280, 1180, 1030; H 1.26(t, 3H, J 7.1), 1.33 (t, 3H, J 7.1), 3.48 (s, 2H), 4.17 (q, 2H, J 7.1),4.29 (q, 2H, J 7.1), 7.26¡Ó7.38 (m, 4H), 7.82 (s, 1H); m/z 296 (M,65%), 251 (93), 223 (48), 151 (80), 149 (58), 15 (100).Ethyl (E)-4-(4-uorophenyl )-3-ethoxycarbonyl-3-enoate 4b.Yield,73%. Oil; max/cm£¾1; 2980, 1740, 1640, 1480, 1270, 1210, 1030; H1.20 (t, 3H, J 7.1), 1.26 (t, 3H, J 7.1), 3.42 (s, 2H), 4.11 (q, 2H,J. Chem.Research (S),1998, 642¡Ó643$Table 1 Preparation of substituted -3-alkoxycarbonyl-b,g-unsaturated estersCompound R R' Yield (%)a4ab 4-ClC6H4 Et 704b 4-FC6H4 Et 734c 4-CH3C6H4 Et 714d 4-BrC4H6 Et 704e 4-CF3C6H4 Et 654f C6H5 Et 654g Prn Et 654h 2-Furyl Et 644i 4-ClC6H4 Me 684j 4-FC6H4 Me 684k 4-CH3C6H4 Me 664l 4-BrC4H6 Me 704m 4-CF3C6H4 Me 63aIsolated yields. bThe NOESY spectrum of 4a showed that the Rgroup is cis with respect with the CH2CO2Et group.Scheme 1 Reagents and conditions: i, NaOR' or NaH¡ÓR'OH,20 8C, 0.5 h, R' Me, Et; ii, dimethyl maleate, 20 8C, 2 h; iii, RCHO,20 8C, 3 h$This is a Short Paper as dened in the Instructions for Authors,Section 5.0 [see J.Chem. Research (S), 1998, Issue 1]; there is there-fore no corresponding material in J. Chem. Research (M).*To receive any correspondence.642 J. CHEM. RESEARCH (S), 1998J 7.1), 4.22 (q, 2H, J 7.1), 6.95¡Ó7.05 (m, 2H), 7.20¡Ó7.37 (m, 2H),7.73 (s, 1H); m/z 281 (M1, 13%), 280 (M, 49), 235 (89), 234(51), 206 (35), 134 (64), 133 (100), 115 (15).(Found: C, 63.94;H, 6.25. C15H17FO4 requires C, 64.28; H, 6.11%).Ethyl (E)-4-(4-methylphenyl )-3-ethoxycarbonylbut-3-enoate 4c.Yield, 71%. Bp 161 8C at 1 mmHg (lit.,5 bp 135¡Ó138 8C at 0.4Torr); max/cm£¾1; 2980, 1740, 1640, 1450, 1270, 1130, 1030; H 1.26(t, 3H, J 7.1), 1.33 (t, 3H, J 7.1), 2.36 (s, 3H), 3.53 (s, 2H), 4.20 (q,2H, J 7.1), 4.22 (q, 2H, J 7.1), 7.11¡Ó7.35 (m, 4H), 7.87 (s, 1H); m/z276 (M, 72%), 231 (44), 230 (68), 202 (52), 131 (98), 129 (100),115 (38), 99 (26).Ethyl (E)-4-(4-bromophenyl )-3-ethoxycarbonyl-3-enoate 4d.Yield,70%.Oil; max/cm£¾1; 2980, 1740, 1640, 1450, 1280, 1180, 1030; H1.26 (t, 3H, J 7.1), 1.32 (t, 3H, J 7.1), 3.47 (s, 2H), 4.17 (q, 2H,J 7.1), 4.28 (q, 2H, J 7.1), 7.21 (dd, 2H, J 1.7, 5.0 Hz), 7.50 (dd,2H, J 1.8, 5.0 Hz), 7.80 (s, 1H); m/z 342 (M1, 68%), 341 (M,26), 340 (M £¾ 1, 65), 297 (100), 295 (96), 188 (50), 160 (13), 129(27), 115 (93) (Found: C, 52.80; H, 5.11.C15H17BrO4 requiresC, 52.80; H, 5.02%).Ethyl (E)-4-(4-triuoromethylphenyl )-3-ethoxycarbonylbut-3-enoate4e.Yield, 65%. Oil; max/cm£¾1; 2950, 1720, 1620, 1500, 1330,1170, 1020; H 1.27 (t, 3H, J 7.1), 1.34 (t, 3H, J 7.1), 3.47 (s, 2H),4.18 (q, 2H, J 7.1), 4.30 (q, 2H, J 7.1), 7.45 (d, 2H, J 8.2), 7.64(d, 2H, J 8.2), 7.89 (s, 1H); m/z 331 (M1, 33%), 286 (20), 285(100), 165 (8), 115 (8) (Found: C, 58.03; H, 5.24. C16H17F3O4requires C, 58.18; H, 5.19%).Ethyl (E)-4-phenyl-3-ethoxycarbonylbut-3-enoate 4f.Yield, 65%.Bp 158 8C at 1 mmHg (lit.,5 bp 132¡Ó134 8C at 0.4 Torr); max/cm£¾1;2980, 1740, 1640, 1450, 1270, 1130; H 1.27 (t, 3H, J 7.1), 1.33(t, 3H, J 7.1), 3.52 (s, 2H), 4.17 (q, 2H, J 7.1), 4.27 (q, 2H, J 7.1),7.30¡Ó7.42 (m, 5H), 7.89 (s, 1H), m/z 263 (M1, 33%), 262 (M,100), 231 (83), 216 (28), 130 (39), 129 (70).Ethyl (E)-3-ethoxycarbonylhept-3-enoate 4g.Yield, 65%.Oil;max/cm£¾1; 2980, 1730, 1650, 1450, 1330, 1240, 1040; H 0.92 (t, 3H,J 7.4), 1.22 (t, 3H, J 7.1), 1.24 (t, 3H, J 7.1), 1.40¡Ó1.53 (m, 2H),2.15 (m, 2H), 3.31 (s, 2H), 4.11 (q, 2H, J 7.1), 4.17 (q, 2H, J 7.1),6.94 (d, 1H, J 7.6); m/z 229 (M1, 40%), 184 (17), 183 (100), 182(27), 155 (15), 154 (13) (Found: C, 63.05; H, 9.04.C12H20O4requires C, 63.14; H, 8.83%).Ethyl (E)-4-(2-furyl )-3-ethoxycarbonylbut-3-enoate 4h.Yield,64%. Bp 137 8C at 1 mmHg (lit.,5 bp 120¡Ó121 8C at 0.5 Torr);max/cm£¾1; 3130, 2980, 1730, 1700, 1480, 1210, 1100; H 1.21 (t, 3H,J 7.2), 1.31 (t, 3H, J 7.2), 3.84 (s, 2H), 4.14 (q, 2H, J 7.1), 4.27(q, 2H, J 7.1), 6.47 (dd, 1H, J 1.7, 3.4), 6.64 (d, 1H, J 3.4), 7.51(d, 1H, J 1.7), 7.53 (s, H); m/z 252 (M, 87%), 207 (61), 179 (100),151 (46), 106 (34), 79 (44).Methyl (E)-4-(4-chlorophenyl )-3-methoxycarbonylbut-3-enoate 4i.Yield, 68%.Bp 165 8C at 1 mmHg (lit.,5 bp, 133¡Ó134 8C at0.3 Torr); max/cm£¾1; 2960, 1740, 1640, 1440, 1260, 1040; H 3.49(s, 2H), 3.72 (s, 3H), 3.82 (s, 3H), 7.29 (d, 2H, J 8.5), 7.34 (d, 2H,J 8.5), 7.83 (s, 1H); m/z 269 (M1, 37%), 268 (M, 100), 239 (36),237 (95), 236 (44), 150 (8), 149 (23), 115 (23).Methyl (E)-4-(4-uorophenyl )-3-methoxycarbonylbut-3-enoate 4j.Yield, 68%, Oil; max/cm£¾1; 2950, 1710, 1640, 1440, 1370, 1270,1020; H 3.52 (s, 2H), 3.74 (s, 3H), 3.83 (s, 3H), 7.06¡Ó7.12 (m, 2H),7.26¡Ó7.37 (m, 2H), 7.86 (s, 1H); m/z 252 (M, 75%), 221 (87), 220(66), 192 (25), 149 (21), 133 (100).(Found: C, 61.97; H, 5.43.C13H13FO4 requires C, 61.90; H, 5.19%).Methyl (E)-4-(4-methylphenyl )-3-methoxycarbonylbut-3-enoate 4k.Yield, 66%.Bp 142 8C at 1 mmHg (lit.,5 bp 138 8C at Torr);max/cm£¾1; 2950, 1740, 1640, 1440, 1280, 1020; H 2.37 (s, 3H), 3.56(s, 2H), 3.73 (s, 3H), 3.82 (s, 3H), 7.19¡Ó7.26 (m, 4H), 7.88 (s, 1H);m/z 249 (M1, 35%), 248 (M, 100), 217 (98), 188 (11), 129 (36),115 (9).Methyl (E)-4-(4-bromophenyl )-3-methoxycarbonylbut-3-enoate 4l.Yield, 70%; Oil; max/cm£¾1; 2950, 1720, 1640, 1490, 1280, 1210,1050; H 3.49 (s, 2H), 3.73 (s, 3H), 3.82 (s, 3H), 7.23 (d, 2H, J 8.4),7.51 (d, 2H, J 8.4), 7.81 (s, 1H); m/z 314 (M1, 100%), 313(M, 28), 312 (95), 283 (63), 281 (63), 201 (41), 174 (54), 115(88) (Found: C, 49.86; H, 4.17.C13H13BrO4 requires C, 49.86;H, 4.18%).Methyl (E)-4-(4-triuoromethylphenyl )-3-methoxycarbonylbut-3-enoate 4m.Yield, 63%. Oil; max/cm£¾1; 2950, 1720, 1620, 1440,1330, 1170, 1050; H 3.49 (s, 2H), 3.74 (s, 3H), 3.84 (s, 3H), 7.47(d, 2H, J 8.2), 7.64 (d, 2H, J 8.2), 7.91 (s, 1H); m/z 303 (M1,12%), 302 (M, 44), 283 (24), 270 (100), 242 (45), 183 (58), 164(19), 115 (44) (Found: C, 55.49; H, 4.33.C14H13F3O4 requiresC, 55.63; H, 4.34%).We thank the National Science Foundation of China andAcademia Sinica for nancial support.Received, 11th March 1998; Accepted, 9th June 1998Paper E/8/03769HReferences1 M. Gordaliza, J. M. M. del Corral, M. A. Castro, M. A.Salinero, A. San Feliciano, J. M. Dorado and F. Valle, Synlett,1996, 1201 and references cited therein.2 F. Perron and K. F. Abizati, Chem. Rev., 1989, 89, 1617.3 W. S. Johnson and G. H. Daub, Organic React., 1951, 6, 1.4 A. F. Cameron, F. D. Duncanson, A. A. Freer, V. W. Armstrongand R. Ramage, J. Chem Soc., Perkin Trans. 2, 1975, 1030.5 S. Linke, J. Kurz, D. Lipinski and W. Gau, Liebigs Ann. Chem.,1980, 542.6 S. W. McCombie and C. A. Luchaco, Tetrahedron Lett., 1997,38, 5775.7 L. F. Tietze and U. Beifuss, Angew. Chem., Int. Ed. Engl., 1993,32, 131; A. Padwa, E. A. Curtis and V. P. Sandanayaka, J. Org.Chem., 1996, 61, 73; L. F. Tietze, Chem. Rev., 1996, 96, 115; P. J.Parsons, C. S. Penkett and A. J. Shell, Chem. Rev., 1996, 96, 195.8 Y. Shen and J. Ni, J. Org. Chem., 1997, 62, 7260; Y. Shen andJ. Ni, J. Chem. Res. (S), 1997, 358.J. CHEM. RESEARCH (S), 1998 643

ISSN:0308-2342    

DOI:10.1039/a803769h

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Photooxidation of Benzyl Alcohols Sensitized byTiO2 in CH3CN in the Presence of Ag2SO4. KineticEvidence for the Involvement of AdsorptionPhenomena$Laura Amori,a Tiziana Del Giacco,a Cesare Rol*a andGiovanni V. Sebastiani*baDipartimento di Chimica, Universita di Perugia, Via Elce di Sotto, 06123 Perugia, ItalybIstituto per le Tecnologie Chimiche, Facolta di Ingegneria, Universita di Perugia, Via G. Duranti,06143 Perugia, ItalyX-Ring substituted benzyl alcohols are photooxidized to the corresponding aldehydes by TiO2 in CH3CN in thepresence of Ag2SO4 and kinetic evidence suggests a changeover of the electron abstraction site from the aromatic moiety(X 4-CH3O, 4-CH3, 4-Cl, H, 3-Cl) to the hydroxylic group (X 3-CF3, 4-CF3), probably owing to the preferentialadsorption of OH on TiO2.It is known that the TiO2 photosensitized oxidation oforganic compounds in aqueous media, in the presence ofoxygen as the electron acceptor, can proceed through a`direct' process (single electron transfer from the substrateto the photogenerated hole, h) or an `indirect' one (sub-strate attack by OH generated from the water oxidation).1In this respect, we have observed that deaerated CH3CN,when used in the presence of Ag as the electron acceptor,is an oxidatively inert medium suitable for mechanisticstudies of the rst process.2 In particular, it has beenpossible to study, through reaction product analysis, somechemical properties of alkylaromatic radical cations[eqns.(1)¡Ó(3)].2TiO2h£¾£¾£¾£¾4TiO2h TiO2e£¾ 1TiO2h ArCH2Y £¾4 ArCH2Y£¾: £¾4 Products 2TiO2e£¾ Ag £¾4 Ag 3An interesting result was the presence, within the reactionproducts from 1-phenylpropan-2-ol and its correspondingmethyl ether,2b of a compound (benzyl methyl ketone)derived from oxidation of the OH group, a thermo-dynamically very unfavoured site with respect to the psystem towards electron abstraction. One of the suggestedexplanations of this unexpected behaviour has been theincreased oxidizability of the hydroxy group due to its pre-ferential adsorption at the TiO2 surface.2b,3 Accordingly,this hypothesis was already formulated to explain the betteroxidizability of OH with respect to phenyl in 5-phenyl-pentan-1-ol (5-phenylpentanal and 5-phenylpentanoic acidwere the predominant reaction products).4With the aim of providing more quantitative informationon this argument we have undertaken a systematic studyof the TiO2 photosensitized oxidation of a series ofbenzyl alcohol derivatives [X-C6H4CH2OH, with X H (1),4-CH3O (2), 4-CH3 (3), 3-Cl (4), 4-Cl (5), 3-CF3 (6), 4-CF3(7)].The reactions were carried out by external irradiation ofa deaerated acetonitrile solution of the benzyl alcoholderivative in the presence of TiO2 and Ag2SO4.Under thesemild conditions a quite ecient process occurs leading tothe corresponding benzaldehyde (Table 1) in fair to goodyield (34¡Ó73%) and with satisfactory material balance(generally e95%).At high substrate conversion (see entry5 from 1) the benzaldehyde selectivity is not signicantlyreduced (a small amount of benzoic acid is also formed).No reaction takes place if the substrate solution is irradiatedin the absence of either TiO2 or Ag2SO4. With oxygen as theelectron acceptor a lower substrate conversion is observed(compare entry 2 with entry 1). The unexpected eciencyof the process even with scarcely oxidizable alcohols(with electron-withdrawing substituents) is noteworthy.Forexample the TiO2 induced photooxidation of the 4-CF3derivative yields in 2 h a conversion in aldehyde (47%, entry8) not much lower than that of unsubstituted alcohol (73%,entry 5).For comparison, we have carried out the photooxidationof the same substrates in the homogeneous phase (CH3CN,O2, at room temperature) sensitized by 2,4,6-triphenyl-pyrylium tetrauoroborate (TPPBF4£¾), an electron transferoxidant whose redox potential at the excited state(E*red=EredDEoo=2.53 V vs.SCE)5 is similar to that ofthe TiO2 valence band edge (E32.4 V).6 Under these con-ditions benzyl alcohol was much more eciently converted(after 4 h) into products (benzaldehyde, 39%, and benzoicacid, 41%) than the 4-CF3 derivative (4-triuoromethyl-benzaldehyde was obtained in 8% yield).The relative photooxidation rates have also been deter-mined by means of competition kinetics. An initial obser-vation is that, in line with the behaviour observed in Table 1,the rate of the reaction is signicantly increased by theJ.Chem. Research (S),1998, 644¡Ó645$Table 1 Product yields in TiO2 photosensitized oxidation ofring substituted benzyl alcohols in deaerated CH3CN and in thepresence of Ag2SO4aEntry X t/minUnreactedsubstrate (%)bAldehyde(%)b1 4-CH3O (2) 15 54 412c 15 68 193 4-CH3 (3) 30 63 344 H(1) 60 52 435 120 14 73d6 3-Cl (4) 120 50 487 3-CF3 (6) 120 47 528 4-CF3 (7) 120 51 47aNo reaction takes place in the absence of TiO2 or Ag2SO4.bWith respect to starting material.cIn the absence of Ag2SO4and in aerated medium. dBenzoic acid (3%) is also formed.$This is a Short Paper as dened in the Instructions for Authors,Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there-fore no corresponding material in J. Chem. Research (M).*To receive any correspondence (e-mail: rol@unipg.it).644 J. CHEM. RESEARCH (S), 1998electron-donating groups 4-CH3O and 4-CH3 while a muchlower reactivity is observed with the electron-withdrawingsubstituents 3-CF3 and 4-CF3.A quantitative assessment ofthe phenomenon is provided by the log krel/Ep plot7 (Fig. 1).In particular a good linear correlation (r 0.992) isobserved for benzyl alcohols with X 4-CH3O, 4-CH3, 4-Cl, H, 3-Cl. This behaviour is in line with a single electrontransfer (SET) rate determining step to (TiO2)h+ where theelectron is removed from the aromatic moiety [eqn. (4)].The low value of the slope (£¾2.1 V£¾1) could be related toa substrate like transition state, as expected for a slightlyexoergonic step.7In contrast the points for the benzyl alcohols with signi-cantly higher reduction potential (X 3-CF3 and 4-CF3) liewell above the line tted by the other substituents; in par-ticular the last two compounds show a similar and higherthan expected reactivity.A plausible explanation of thisphenomenon could be the involvement of an alternative oneelectron transfer from the OH group [eqn.(5)], a processmuch less kinetically inuenced by the substituent eect.The changeover of electron abstraction site is not justiableon a thermodynamic basis, as the reduction potential of thealcoholic site (reasonably similar to that of an aliphaticalcohol, Ep13 V8) is higher than that of 4-triuoromethyl-benzyl alcohol (Ep=2.70 V). This behaviour is in line withthe increase of oxidizability of the OH group, explainedon the basis of its preferential adsorption with respect to thephenyl ring;2b,4 in our case OH could favourably compete,with electron abstraction, with an aromatic site deactivatedby substituents with a suciently high electron-withdrawingeect (as 3- or 4-CF3). Further kinetic evidence that theobserved phenomenon is connected to the medium hetero-geneity (probable involvement of preferential adsorption)could be the relative reactivity values obtained from thephotooxidation of 1, 3 and 6 in the homogeneous phasein the presence of TPPBF4£¾; in eect, the expected decreas-ing reactivity trend as a function of increasing reductionpotential of substrate is observed [k(4-CH3)/k(H) 1.8 andk(3-CF3)/k(H) 0.024].It should be noted that the high reduction potential of thetwo triuoromethyl substituted derivatives could suggestthe involvement of a mechanism dierent from electrontransfer such as radical benzylic hydrogen transfer, notdepending on reduction potential.Otherwise this hypothesisis not plausible in CH3CN, even with scarcely oxidizablesubstrates; for example the observed higher reactivity ofthe primary vs.the secondary alcoholic site in the TiO2sensitized photooxidation of pentane-1,4-diol9 (an aliphaticalcohol, a compound with an high reduction potential, seeabove) is opposite to the behaviour expected in a radicalprocess. In eect, the observed trend has been justiedthrough a preferential electron transfer to the less hinderedand more eciently adsorbed primary group with respect tothe secondary one.The benzylic radical obtained from deprotonation[eqn.(6)] of both cation radicals 8 and 9 should undergo afurther oxidation (probably by Ag) giving the protonatedform of the corresponding benzaldehyde [eqn. (7)].2dExperimentalA solution of benzylic alcohol (0.22¡Ó0.24 mmol) in N2 purgedCH3CN (20 ml, HPLC grade) was externally irradiated (through aPyrex lter) by a 500 W high pressure mercury lamp, with stirringat room temperature, in the presence of 130 mg of TiO2 (Aldrich,99.9%, anatase, dried at 110 8C) and 0.30 mmol of Ag2SO4.TheTiO2 powder was then ltered through double paper and repeatedlywashed with CH3CN and diethyl ether; the reaction mixture waspoured into water and extracted with diethyl ether. The quantitativeanalysis of the crude product was performed by 1H NMR and/orby GC relative to a suitable internal standard. The same photo-chemical reactor was used to irradiate a solution of the alcohol(0.5 mmol) and TPPBF4£¾ (0.021 mmol) in O2 purged CH3CN(20 ml).Competitive experiments were performed at 25 8C by irradiation(multilamp photochemical reactor, l 350230 nm) of mixturescontaining equimolar amounts of two substrates and determination(by GC with respect to an internal standard) of the amount ofunreacted starting material at dierent times.Ep values were obtained by cyclic voltammetry (100 mV s£¾1,1 mm diameter platinum disc anode) in CH3CN/LiClO4 (0.1 M).This work has been carried out with the contribution ofthe Ministry of University and Technological Research(MURST) and the National Council of Research (CNR).Received, 10th March 1998; Accepted, 10th June 1998Paper E/8/01949EReferences1 M.A. Fox and M. T. Dulay, Chem. Rev., 1993, 93, 341.2 (a) E. Baciocchi, C. Rol, G. C. Rosato and G. V. Sebastiani,J. Chem. Soc., Chem. Commun., 1992, 59; (b) E. Baciocchi,C. Rol, G. V. Sebastiani and L. Taglieri, J. Org.Chem., 1994, 59,5272; (c) E. Baciocchi, T. Del Giacco, M. I. Ferrero, C. Rol andG. V. Sebastiani, J. Org. Chem., 1997, 62, 4015; (d) E. Baciocchi,M. Bietti, M. I. Ferrero, C. Rol and G. V. Sebastiani, ActaChem. Scand., 1998, 52, 160.3 Aquatic and Surface Photochemistry, ed. G. R. Helz, R. G. Zeppand D. G. Crosby, Lewis Publishers, London, 1994, p. 343.4 M. A. Fox and A. A. Abdel-Wahab, J. Catal., 1990, 126, 693.5 Photoinduced Electron Transfer, ed. M. A. Fox and M. Chanon,Elsevier, Amsterdam, 1988, Part A, p. 470.6 Kabir-ud-Din, R. C. Owen and M. A. Fox, J. Phys. Chem., 1981,85, 1679.7 Ref. 5, Part B, p. 220 and references cited therein.8 G. Sundholm, Acta Chem. Scand., 1971, 25, 3188.9 M. A. Fox, H. Ogawa and P. Pichat, J. Org. Chem., 1989, 54,3847.Fig. 1 Plot of log krel vs. Ep for TiO2 photosensitized oxidationof X-ring substituted benzyl alcohols in deaerated CH3CN and inthe presence of Ag2SO4J. CHEM. RESEARCH (S), 1998 645

ISSN:0308-2342    

DOI:10.1039/a801949e

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Amidoethylation of Anthracene Hydride by N-Aroylaziridines: Inner-sphere Single Electron Transfer (SET) and Radical Coupling confirmed$ P.-Y. Lin and H. Stamm* Faculty of Pharmacy, University of Heidelberg, Neuenheimer Feld 346, D-69120 Heidelberg, Germany Regioselectivity (near 1:1) of substitutive ring opening of 1-benzoyl-2-methylaziridine by anthracene hydride is incompatible with common nucleophilic attack and thus confirms the radical coupling path. Reactions of N-aroylaziridines with excess anthracene hydride (AH¢§) may be exempli¢çed by means of 1a (Scheme 1).Aziridino ketyl 4a is an essential intermediate3 generated by benzylic fragmentation (BFR)4 of the rapidly formed3 carbonyl adduct 2a. Homolytic ring cleavage of 4a a€ords the amidatoalkyl radical 5a, a precursor of the main product 6. The second product is 7. When the aziridine ring of 1a carries substituents, ana- logues of 7 are obtained3 unless they arise from 2-phenyl- aziridines and are unstable under usual conditions.3,5 The assumption3 that 7 and its analogues are formed by coup- ling of amidatoalkyl radicals with anthracenide A ¢§ was supported by a regioselectivity of ring opening that seemed to exclude a direct SN2-like path to analogues of 7 and hence also to 7.Subsequently it was found6 from a study of 1-acyl-2,2-dimethylaziridines that SN2-like ring opening may require planarization of the nitrogen pyramid thereby shifting the mechanism to a borderline type whose regio- selectivity is compatible with the AH¢§ results.This reopened the mechanistic question since the very fast initial carbonyl attack is reversible.7 Ring opening of 1-acyl-2-methylaziridines by strong nucleophiles was recently8 shown to strongly prefer cleavage of the N¡¾CH2 bond. AH¢§ and 2-methyl-1-pivaloylaziridine provided a mixture of products (total 94%) with an overall regioselectivity isopropylamides :n-propylamides of 35 :1. The reaction of xanthenyl anion (oxa analogue of AH¢§ devoid of the BFR path) with 1b yielded 82% of benzoyl- xanthene and 14.5% of amidoethylated xanthenes with an iso to normal regioselectivity of 28:1.Thus, one may expect a ratio of about 30:1 if i-10 and n-10 (Scheme 2) are formed from 1b and AH¢§ only, or mainly, by nucleophilic ring opening. Two three-day runs of 10 mmol of 1a with 16 mmol of AH¢§Lia in 200 ml of THF provided 58% (47%) of iso- propylamide i-9, 14% (18%) of n-propylamide n-9, 9% (4%) of i-10 and 9% (5%) of n-10 (values in parentheses are the yields of the second run).The yields of both 10 are crude yields in the sense that they were estimated by 1H NMR from fractions containing minor amounts of unknown products, probably isomers of 10, one of them being 11 (see below). But the yield ratios i :n a 1 (0.8), deter- mined from the methyl doublets at 1.21 and 0.94 ppm, are su.ciently reliable. These ratios of isomeric 10 are far from the 30:1 ratio expected for an SN2 mechanism.Both 10 arise consequently only or nearly so from coupling of anthracenide A ¢§ (generated by BFR) with amidatoalkyl radicals i-8 and n-8. Moreover, coupling with position 1 of A ¢§ obviously formed traces of 11 (one or two products with isomeric side chains). 11 was identi¢çed in the insepar- able mixture of isomeric 10 by characteristic 1H NMR signals for the non-aromatic double bond. A doublet (J 10.4) for H-4 at 6.70 ppm shows ¢çne splitting (ca. 1.1 Hz) of the lines from coupling with H-10. A doublet (J 10.4) of approximated triplets (J ca. 5) at 6.08 ppm comes from H-3, the triplets indicating attachment of the amidatopropyl chain to position 1. Ole¢çnic and additional aromatic signals are in accord with those of 2-vinylnaphthalene.10 There were at least four methyl doublets (J ca. 6.8 Hz, at 1.02, 1.11, 1.31 and 1.42 ppm) in addition to those of both 10. This is compatible with a mixture of i-11 and n-11 when one considers diastereoisomerism.However, part of these signals may come from structural isomers of 11, e.g. Y carried in position 2. Weak signals in the range of 5.9¡¾6.7 ppm point to isomerism in the non-aromatic ring. Cleavage 4b 4 i-8 will be kinetically controlled (cf. ref. 9) and reduction of the amidatoalkyl radicals by a second 4b forms probably the primary carbanion faster than the secondary one. It is therefore not surprising to ¢çnd much more i-9 than n-9. Experimental The reactions were performed as described in ref. 4 starting with 17 mmol of dihydroanthracene AH2 and 16 mmol BuLi (hexane). The reactions were quenched with acetic acid. The residue obtained after the usual workup was chromatographed (silica gel Merck, 0.063¡¾0.200 mm, 40 cm4 cm, toluene¡¾ethyl acetate 9:1); compo- J. Chem. Research (S), 1998, 646¡¾647$ Scheme 1 $This is a Short Paper as de¢çned in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there- fore no corresponding material in J.Chem. Research (M). *To receive any correspondence. 646 J. CHEM. RESEARCH (S), 1998site fractions were analyzed by 1H NMR (CDCl3, Me4 Si internal). J values are given in Hz. Run 1 provided hydrocarbons and their oxidation products; 72 mg of unknown products and 120 mg of a 3:1 mixture of i-10 (90 mg) and n-10 (30 mg) followed. A crystal of i-10 could be manu- ally picked out. Continued elution yielded 482 mg of a 1:1.2 mixture of i-10 (219 mg, total 309 mg �� 9%) and n-10 (263 mg, total 293 mg �� 9%) containing a trace of 11 (1H NMR data given in the text).Further elution gave 146 mg of i-9 and 1022 mg of a mixture of 798 mg (total 944 mg �� 58%) of i-9 and 224 mg (14%) of n-9. i-10: mp 192¡À194 8C; max/cm¡¦1 3303 (NH), 1636 (amide I), 1538 (amide II); dH 1.21 (d, J 6.6, Me), 1.87 (m, NCCH2), 3.88 (d, J 18.4, 10-H pseudo eq), 4.08¡À4.31 (m, 9-H and NCH), 4.12 (d, J 18.3, 10-H pseudo ax), 5.90 (d br, J 8.2, NH), 7.17¡À7.32 (m, 8 ArH), 7.38¡À7.42 (m, m-H and p-H of Ph), 7.63 (m, o-H of Ph).n-10 (in mixture with i-10): dH 0.89 (d, J 6.8, Me) (m, NCCH), 3.35 (dtapprox, J 13.8 and ca. 6.0, 1 H of NCH2), 3.49 (dtapprox, J 13.8 and ca. 6.7, 1 H of NCH2), 3.81 (d, J 7.4, 9-H), 3.85 (d, J 18.3, 10-H pseudo-eq), 4.13 (d, J 18.3, 10-H pseudo-ax), 5.84 (s br, NH), aromatic signals cannot be distinguished from those of i-10. Mixture of i-10 and n-10: (Found: C, 84.3; H, 6.9; N, 4.0.C24H23NO requires C, 84.4; H, 6.8; N, 4.1%); max/cm¡¦1 3313 (NH), 1631 (amide I), 1540 (amide II). Run 2 provided hydrocarbons and their oxidation products; 65 mg of unknown products and 219 mg of a mixture of i-10 (91 mg) and n-10 (128 mg) followed. Further elution yielded 182 mg of a mixture containing mainly (more than 90 mg totalling to 279 mg �� 9%) 10 in a ratio of 55 mg (total 146 mg �� 4%) of i-10: 35 mg (total 163 mg �� 5%) of n-10. This mixture contained also some 11.Continued elution provided 84 mg of i-9 and 976 mg of a mixture consisting of 687 mg (total 771 mg �� 47%) of i-9 and 289 mg (18%) of n-9. Received, 29th May 1998; Accepted, 10th June 1998 Paper E/8/04044C References 1 Arene Hydrides, Part 16. Part 15: T. Mall and H. Stamm, J. Chem. Soc., Perkin Trans. 2, 1997, 2135. 2 Aziridines, Part 73. Part 72: Arene Hydrides, Part 15; see ref. 1. 3 H. Stamm, A. Sommer, A. Woderer, W. Wiesert, T. Mall and P. Assithianakis, J. Org. Chem., 1985, 50, 4946. 4 H. Stamm, T. Mall, R. Falkenstein, J. Werry and D. Speth, J. Org. Chem., 1989, 54, 1603. 5 H. Stamm and R. Falkenstein, Chem. Ber., 1990, 123, 2227. 6 P.-Y. Lin, K. Bellos, H. Stamm and A. Onistschenko, Tetrahedron, 1992, 48, 2359. 7 T. Mall and H. Stamm, Chem. Ber., 1988, 121, 1349. 8 P.-Y. Lin, G. Bentz and H. Stamm, J. Prakt. Chem., 1993, 335, 23. 9 J. Werry, H. Stamm, P.-Y. Lin, K. R. Falkenstein, S. Gries and H. Irngartinger, Tetrahedron, 1989, 45, 5015. 10 C. V. Pouchert and J. R. Campbell, The Aldrich Library of NMR Spectra, Vol. IV, Aldrich Chemical Company, 1974. Scheme 2 J.

ISSN:0308-2342    

DOI:10.1039/a804044c

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Efficient Catalytic Oxidation of Primary AromaticAmines to Azo Derivatives by Manganese(III)Tetraphenylporphyrin$Mohammad Hossein Habibi,* Shahram Tangestaninejad andValiollah MirkhaniDepartment of Chemistry, Esfahan University, Esfahan, 81744, IranThe oxidation of primary aromatic amines to the corresponding azo derivatives has been observed in catalytic systemscontaining manganese(III) tetraphenylporphyrin and sodium periodate in the presence of heterocyclic nitrogen basesacting as axial ligands.The catalytic role of metallo-porphyrins for hydroxylationof alkanes,1,2 epoxidation of alkenes,3,4 demethylation ofN-methylbenzylamine,5 oxidation of nitroso6 and primaryaromatic amines7¡Ó10 to nitro derivatives has been observed.In this report, we describe a periodate-metalloporphyrinsystem for oxidation of primary aromatic amines to azoderivatives.One important aspect of this catalytic system is themodication of the oxidation rate by addition of a smallamount of imidazole to the mixture.The correspondingresults of the eect of various axial ligands on oxidationof para-toluidine are presented in Table 1. The formationof azo product in the absence of axial ligand is very slowand the yields are always below 10% within 90 min, whereas100% GLC yield of azo product is obtained during thesame period in the catalyzed reaction with imidazole as theaxial ligand. The yield of azo product in the oxidationof para-toluidine decreased in the following order usingdierent axial ligands: imidazole 4-methylpyridine>2-methylpyridine >pyridine.Reactions were performed at room temperature in airin CH2Cl2¡ÓH2O containing the primary aromatic amines,periodate, axial ligand and tetraphenylporphyrinato-manganese(III) chloride (MnTPPCl) in 83:166:17:1 ratios,respectively.This catalytic system led to oxidation ofprimary aromatic amines RC6H4NH2 1¡Ó13 to azo deriva-tives (1a¡Ó13a) (Scheme 1) in good isolated yields (38¡Ó85%)(Table 2).RC6H4NH2 £¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾£¾4MnTPPCl; NaIO4; room temp:CH2Cl2¡ÓH2O; Imidazole; Bu4NBrRC6H4N.NC6H4R1¡Ó13 1a¡Ó13a1 R p-Et2 R p-Me3 R o-Me4 R p-OMe5 R o-OMe6 R m-OMe7 R H8 R o-CN9 R o-Cl10 R p-NO211 R m-NO212 R o-NO213 R p-BrScheme 1Control experiments carried out on the amines showedthat, in the absence of catalyst, no oxidation to azo com-pounds occurs.The eect of axial ligands clearly indicate that an electrondonating axial substituent coordinated to the metal isessential for the above oxidation of primary aromaticamines with MnTPPCl as catalyst.The highest coordinativecapability of imidazole compared to other axial ligands andamines is shown by the pronounced spectral changes ofthe MnTPPCl Soret band at 477.5 nm in the presence ofimidazole.The oxidation product of benzylamine under the aboveconditions was benzaldehyde with 90% isolated yield and100% selectivity.ExperimentalMnTPPCl was prepared according to the literature pro-cedures.11,12 In a typical reaction, a 50 ml ask was chargedwith primary aromatic amine (1 mmol), MnTPPCl (0.012 mmol),imidazole (0.2 mmol), CH2Cl2 (10 ml), NaIO4 (2 mmol) in H2O(10 ml) and 0.05 mmol of tetrabutylammonium bromide as a phasetransfer catalyst. The reaction was magnetically stirred at roomtemperature for 1¡Ó5 h.The progress of the reaction was monitoredby gas chromatography and the products were separated by columnchromatography with silica gel.All the oxidation products wereclearly identied by IR, 1H NMR and UV¡ÓVIS spectral data.J. Chem. Research (S),1998, 648¡Ó649$Table 1 Effect of various axial ligands on oxidation of paratoluidineto azo product in 90 minaAxial ligand Azo yield (%)b Turnover per hImidazole 100 55.554-Methylpyridine 25 13.882-Methylpyridine 19 10.55Pyridine 12 6.67Without axial ligand 10 5.55aReaction conditions: para-toluidine (1 mmol), MnTPPCl(0.012 mmol), axial ligand (0.2 mmol), NaIO4 (2 mmol),tetrabutylammonium bromide (0.05 mmol), CH2Cl2/H2O(10 ml/10 ml).bGLC yields based on starting para-toluidine.Table 2 Oxidation of primary aromatic amines (1¡Ó13) to azoderivatives (1a¡Ó13a) with NaIO4 catalyzed by MnTPPCl in thepresence of imidazoleaAmine Azo yield (%)b Reaction time/h1 85 22 80 13 80 24 80 1.55 80 26 80 37 70 28 60 39 50 410 48 511 63 512 40 513 38 1.5aReaction conditions: aromatic amine (1 mmol), MnTPPCl(0.012 mmol), axial ligand (0.2 mmol), NaIO4 (2 mmol),tetrabutylammonium bromide (0.05 mmol), CH2Cl2/H2O(10 ml/10 ml).bIsolated yields based on starting aromatic amine.$This is a Short Paper as dened in the Instructions for Authors,Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there-fore no corresponding material in J. Chem. Research (M).*To receive any correspondence.648 J. CHEM. RESEARCH (S), 1998Thanks are expressed to Esfahan University Research Council for Rnancial support.Received, 11th March 1998; Accepted, 9th June 1998 Paper E/8/01980K References 1 A. Maldotti, C. Bartocci, G. Varani, A. Molinari, P. Battioni and D. Mansuy, Inorg. Chem., 1996, 35, 1126. 2 D. Dolphin, T. G. Traylor and L. Y. Xie, Acc. Chem. Res., 1997, 30, 251. 3 A. J. Appleton, S. Evans and J. R. Lindsay Smith, J. Chem. Soc., Perkin Trans. 2, 1996, 281. 4 R. Ho€man, A. Robert and B. Meunier, Bull. Soc. Chim. Fr., 1992, 129, 85. 5 J. R. Lindsay Smith and D. N. Mortimer, J. Chem. Soc., Perkin Trans. 2, 1986, 1743. 6 K. A. Jorgenson, J. Chem. Soc., Chem. Commun., 1987, 1405. 7 S. Tollari, D. Vergani, S. BanR and F. Porta, J. Chem. Soc., Chem. Commun., 1993, 442. 8 S. Cenini, F. Porta and M. Pizzoti, J. Mol. Cat., 1982, 15, 297. 9 F. Porta, C. Crotti, S. Cenini and G. Palmisano, J. Mol. Cat., 1989, 50, 333. 10 F. Porta, S. Tollari, F. Ragaini and C. Crotti, Dioxygen Activation and Homogeneous Catalytic Oxidation, ed. L. I. Smandi, Elsevier, Amsterdam, 1991, p. 531. 11 C. A. Busby, R. K. Dinello and D. Dolphin, Can. J. Chem., 1975, 53, 1554. 12 A. Harriman and G. Porter, J. Chem. Soc., Faraday Trans. 2, 1979, 75, 1532. J. CHEM. RESEARCH (S), 1998 649

ISSN:0308-2342    

DOI:10.1039/a801980k

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Facile Synthesis of 6b-Hydroxy-(7aH)-eudesm-4-en-3-one and b-Cyperone$Gang Zhou, Zhaoming Xiong, Yonggang Chen and Yulin Li*National Laboratory of Applied Organic Chemistry and Institute of Organic Chemistry,Lanzhou University, Lanzhou 730000, P.R. ChinaA stereoselective total synthesis of 6-hydroxy-(7H)-eudesm-4-en-3-one 1 and -cyperone 12 starting from()-dihydrocarvone 7 is described.A number of C-6 oxyfunctionalized eudesmanes andb-dihydroagarofurans, such as compounds 3¡Ó6,1 have beenisolated from natural sources.However reports on thesynthesis of this particular kind of compound are few andgenerally start from a-santonin 2.2 Our interest of study onthe synthesis of this kind of compound prompted us toinvestigate a new synthetic route from the cheap material()-dihydrocarvone 7.Recently, Syah and Ghisalberti3 isolated the sesquiterpene6b-Hydroxy-(7aH)-eudesm-4-en-3-one 1 from Eremo-phila spectabilis subsp. brevis, and determined its structureby spectroscopy and X-ray diraction.Herein we reportan ecient and practical synthesis of 1 from ()-dihydro-carvone 7 in ve steps.As shown in Scheme 2, a-cyperone 8 was diastereo-selectively prepared from ()-dihydrocarvone 7 by a two-step procedure.4 Regiospecic hydrogenation of a-cyperone8 with Wilkinson catalyst5 for 48 h aorded 9 quantitatively.Treatment of 9 with acetic anhydride and acetyl chloride6gave the dienol acetate 10 in 98% yield, which was epoxi-dized with m-chloroperbenzoic acid (mCPBA)7 at roomtemperature to give an epimeric mixture of 1 and 11 ina combined yield of 75% with a ratio 1:2 due to thehindrance of the b-methyl group at C-10 in 10.It is worthnoting that oxidation of 10 with Oxone8 stereospecicallygave 11 in 50% yield. The spectral data of 1 are identicalwith those of the natural product.3The mixture of 1 and 11 was dehydrated smoothly withCuSO4/SiO29 to aord b-cyperone 12 quantitatively. Theoverall yield of b-cyperone 12 from starting material is twiceas much as that obtained previously.10In summary, we have developed a synthetic methodologyfor introduction of a hydroxy group at C-6 in the eudes-mane skeleton, which may be used in the synthesis of other6-oxyfunctionalized natural eudesmanes and dihydroagaro-furans, it is also an ecient synthetic route for synthesis ofb-cyperone.ExperimentalFor column chromatography, 200¡Ó300 mesh silica gel and60¡Ó90 8C light petroleum were used.IR spectra were recorded on aNicolet FT-170SX spectrometer as liquid lms, 1H NMR spectraon Bruker AM-400 spectrometers with SiMe4 as internal standardand CDCl3 as solvent and mass spectra on a V.G.ZAB-HS spec-trometer (EI, 70 eV). Elemental analysis was performed on anItalian 1106 analyzer.Hydrogenation of -Cyperone 8.A solution of -cyperone 8(32 mg, 0.147 mmol) and [RhCl(PPh3)3](catalyst) in dry benzene(5 ml) was stirred under a hydrogen atmosphere at r.t. for 48 h.After ltration, the solvent was removed and the crude productpuried by silica gel chromatography to yield compound 9 (31 mg,98%) as colourless oil, []D12146.1 (c 1.09, CHCl3); ~max/cm£¾12958, 2927, 2869, 1667; H (80 MHz) 0.68 (3 H, br s, 11-Me), 0.96(3 H, br s, 11-Me), 1.17 (3 H, s, 10-Me), 1.75 (3 H, s, 4-Me);m/z 220 (M, 84), 205 (24), 177 (85), 149 (47), 135 (100), 91 (64)(Found: C, 81.60; H, 10.61.Calc. for C15H24O: C, 81.82;H, 10.91%).Acetylation of compound 9.A mixture of compound 9 (30 mg,0.135 mmol), acetic anhydride (1 ml) and acetic chloride (1.5 ml)was heated at reux under an argon atmosphere for 1.5 h.Aftercooling, the resulting light yellow solution was concentrated to dry-ness in vacuo. The residue was dissolved in Et2O (30 ml) and washedwith sat. NaHCO3 (35 ml), water (10 ml) and brine (25 ml),and dried over anhydrous MgSO4. After removal of the solvent, theoily residue was chromatographed on silica gel to give the dienolacetate 10 (35 mg, 98%) as a light yellow oil, []D1224.8 (c 2.22,J.Chem. Research (S),1998, 650¡Ó651$Scheme 1Scheme 2 Reagents and conditions: a, ref. 4; b, H2,[RhCl(PPh3)3], dry benzene; c, Ac2O, AcCl; d, mCPBA, CH2Cl2;e, Oxone, H2O¡ÓTHF; f, CuSO4/SiO2, CCl4$This is a Short Paper as dened in the Instructions for Authors,Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there-fore no corresponding material in J. Chem. Research (M).*To receive any correspondence (e-mail: liyl@lzu.edu.cn).650 J. CHEM.RESEARCH (S), 1998CHCl3); ~/cm£¾1 3397, 2951, 2928, 2875, 1755, 1660; H (80 MHz)0.88 (3 H, d, J 6.6, 11-Me), 0.92 (3 H, d, J 6.6, 11-Me), 1.02 (3 H,s, 10-Me), 1.65 (3 H, br s, 4-Me), 2.17 (3 H, s, Ac-H), 5.49 (1 H, d,J 2.4 Hz, 6-H); m/z 262 (M, 6), 220 (14), 203 (12), 177 (100), 133(14), 105 (4). (Found: C, 75.89; H, 9.81. Calc. for C17H26O2:C, 77.09; H, 9.92%).Epoxidation of Dienol Acetate 10.To a solution of compound10 (25 mg, 0.095 mmol) in CH2Cl2 (5 ml) was added mCPBA (70%,24 mg) with stirring at r.t.The mixture was stirred at r.t for 24 h.After the usual work-up, the crude products were puried by ashchromatography to give 1 (6 mg, 27%) and 11 (11 mg, 48%)as white needle crystals. Compound 1: mp 97¡Ó988C; []D1563.8(c 0.61, CHCl3); ~/cm£¾1 3455, 2937, 1656, 1598; H (400 MHz)1.00 (3 H, d, J 6.8, 11-Me), 1.03 (3 H, d, J 6.8, 11-Me), 1.38 (3 H,s, 10-Me), 1.86 (3 H, s, 4-Me), 4.98 (1 H, br d, J 2.6 Hz, 6-H); m/z236 (M, 47), 221 (9), 193 (100), 175 (9), 149 (5), 137 (46), 123 (55),111 (13), 91 (29) (Found: C, 76.01; H, 10.10. Calc.for C15H24O2:C, 76.27; H, 10.17%). Compound 11: mp 102¡Ó103 8C; []D1586.6(c 1.22, CHCl3); H (400 MHz) 0.88 (3 H, d, J 6.8, 13-H), 0.97(3 H, d, J 6.8, 12-H), 1.20 (3 H, s, 14-H), 2.04 (3 H, s, 15-H), 4.44(1 H, br d, J 10.8 Hz, 6-H); m/z 236 (M, 25), 208 (6), 193 (18), 147(8), 123 (100), 109 (19); ~/cm£¾1 3422, 2955, 2931, 1594 (Found:C, 76.05; H, 10.10. Calc. for C15H24O2: C, 76.27; H, 10.17%).Oxidation of Dienol Acetate 10 to 11.To a solution of com-pound 10 (10 mg, 0.048 mmol) in aqueous THF (3 ml) was addedNaHCO3 (3 mg) and Oxone (20 mg) at 0 8C.The resulting cloudyslurry was stirred for 8 h at r.t. After dilution with H2O, the mixturewas extracted with diethyl ether (30 ml). The organic phase waswashed with water (25 ml) and brine (25 ml), dried over anhy-drous MgSO4, then concentrated to dryness in vacuo. Puricationby ash chromatography gave pure 11 (5 mg, 56%).Dehydration of Compounds 1 and 11.To a solution of themixture of compound 1 and 11 (1: 2, 10 mg, 0.042 mmol) in dryCHCl3 (5 ml) was added CuSO4/SiO2 (1: 3, 25 mg).The mixture washeated at reux for 2 h. After usual work-up, the crude productswere puried by ash chromatography, leading to the product 12(9 mg, 98%) as a colorless oil. ~/cm£¾1 2963, 2922, 2869, 1655, 1617.H (80 MHz) 0.88 (3 H, d, J 6.6, 11-Me), 0.92 (3 H, d, J 6.6,11-Me), 1.02 (3 H, s, 10-Me), 2.17 (3 H, s, 4-Me); m/z 218 (M, 25),203 (21), 175 (47), 147 (55), 119 (69), 91 (100) (Found: C, 82.43;H, 10.00.Calc. for C15H22O: C, 82.57; H, 10.09%).We are grateful for the nancial support from NationalNatural Science Foundation of China (Grant No. 29732060)and National Laboratory of Elemento-Organic Chemistry atNankai University.Received, 28th May 1998; Accepted, 17th June 1998Paper E/8/03993CReferences1 (a) J. A. Marco, J. F. Sanz and P. D. Hierro, Phytochemistry,1991, 30, 2403; (b) A. A. Ahmed and J. Jakupovic, J. Nat.Prod., 1993, 56, 1821; (c) Y. Q. Tu, Phytochemistry, 1991, 30,271; (d) Y. Shizuri, K. Wada and R. Sugiura, Tetrahedron,1973, 29, 1773.2 (a) A. K. Banerjee, Tetrahedron, 1993, 49, 4761; (b) L. Cardonaand B. Garcifa, Tetrahedron, 1992, 48, 851.3 Y. M. Syan and E. L. Ghisalberti, Aust. J. Chem., 1996, 49, 707.4 Z. M. Xiong, J. Yang and Y. L. Li, Tetrahedron: Asymmetry,1996, 7, 2607.5 M. Brown, J. Org. Chem., 1967, 32, 2013.6 Villotti, C. Djerassi and H. J. Ringold, J. Am. Chem. Soc., 1959,81, 4567.7 D. N. Kirk and J. M. Wiles, Chem. Commun., 1970, 518.8 N. Surayawaushi and P. L. Fuchs, Tetrahedron Lett., 1981, 22,4201.9 T. Nishiguchi and N. Machida, Tetrahedron Lett., 1987, 28,4565.10 R. B. Gammill and T. A. Bryson, Synth. Commun., 1976, 6, 209.J. CHEM. RESEARCH (S), 1998 651

ISSN:0308-2342    

DOI:10.1039/a803993c

出版商:RSC    

年代:1998

数据来源: RSC

摘要:

Novel Fluorination of Small-ring Tertiary Cycloalkanols: Reaction of Diethylaminosulfur Trifluoride with Tertiary Cyclobutanols$ Masayuki Kirihara,* Tomofumi Takuwa, Toshihiro Kambayashi, Takefumi Momose and Yoshio Takeuchi Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Sugitani 2630, Toyama 930-0194, Japan The reaction of diethylaminosulfur trifluoride with a tertiary cyclobutanol afforded a fluorocyclobutane, a (fluoromethyl)- cyclopropane or a homoallylic fluoride.There has been much e€ort to develop novel methods of �Puorination, because �Puorine-containing molecules have become increasingly important in scientiRc and industrial Relds.1 Diethylaminosulfur tri�Puoride (DAST), an agent converting aliphatic alcohols or silyl ethers into alkyl �Puorides under mild conditions, is one of the most con- venient reagents in organic synthesis.2 There have been several reports concerning new �Puorinating methods using DAST.3�}15 Among these methods, we reported that the reaction of DAST with tertiary cyclopropyl silyl ethers causes ring opening to give allylic �Puorides.11 We now report that a tertiary cyclobutanol reacts with DAST to a€ord a �Puorocyclobutane, a (�Puoromethyl)- cyclopropane or a homoallylic �Puoride, Scheme 1.The results of this reaction are summarized in Table 1. Fluoro- cyclobutanes 2 were obtained from the substrates 1a, 1b bearing electron-donating substituents at C-1 (R1=n-C9H19 or Ph).(Fluoromethyl)cyclopropanes 3 resulted with the electron-withdrawing group at C-1 (R1=CN or CO2Me) (1c�}1e). The compound 1f bearing both an electron- withdrawing group at C-1 and electron-donating sub- stituents at C-3 (R1=CN, R3=Ph) gave a homoallylic �Puoride 4 as the main product. A plausible reaction mechanism is depicted in Scheme 2. The Rrst step is nucleophilic displacement of a �Puorine atom in DAST by the oxygen of the substrate 1. Next, the elimination of sulRnyl dimethylamide �Puoride generates a carbocation triad (equilibrium mixture of A, B and C).16 In the cases of compounds bearing electron-donating substi- tuents at C-1, cyclobutyl cations (A) were predominant.On the other hand, cyclopropylmethyl cations (B) predomi- nated in the cases of compounds bearing an electron- withdrawing group at C-1. The homoallylic cation (C) predominated only in the case of the compound having an electron-withdrawing group at C-1 and electron-donating substituents at C-3.Finally, the �Puoride ion attacks the carbocations to a€ord the Rnal products. Experimental Infrared spectra were measured with a Perkin-Elmer 1600 series FT-IR spectrophotometer, 1H and 19F NMR spectra on a JEOL GX270 instrument with tetramethylsilane (for 1H) and chloro- tri�Puoromethane (for 19F) as an internal standard, mass (MS) and high-resolution mass spectra (HRMS) on a JEOL JMS D-200 spectrometer. J. Chem. Research (S), 1998, 652�}653$ Scheme 1 Reagents and conditions: i, DAST, CH2Cl2, room temperature Table 1 Entry Starting material Products 1 2 3 4 5 6 *An inseparable mixture. The ratio of the products was determined on the basis of the 1H and 19F NMR spectral data.Scheme 2 $This is a Short Paper as deRned in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there- fore no corresponding material in J. Chem. Research (M). *To receive any correspondence. 652 J.CHEM. RESEARCH (S), 1998General Procedure for the Reaction of DAST with Tertiary Cyclo-butanols.To a solution of tertiary cyclobutanol (1.0 mmol) indichloromethane (3 ml) was added DAST (1.0 mmol) at room tem-perature under an inert atmosphere, and the mixture was stirred for30 min. A saturated sodium hydrogencarbonate solution was added,and the resulting mixture extracted with dichloromethane. Theextract was dried over anhydrous sodium sulfate, ltered, and evap-orated to aord the crude product.Purication by chromatography(silica gel, hexane¡Ódichloromethane) gave a pure sample.1-Fluoro-1-nonylcyclobutane 2a.Colorless oil; H (CDCl3) 0.88(3 H, t, J 7.0 Hz), 1.22¡Ó1.35 (12 H, m), 1.35¡Ó1.41 (2 H, m),1.41¡Ó1.50 (1 H, m), 1.61¡Ó1.72 (2 H, m), 1.75¡Ó1.84 (1 H, m),2.02¡Ó2.15 (2 H, m), 2.20¡Ó2.34 (2 H, m); F (CDCl3) £¾130.8 to£¾131.1 (m); IR 2882, 1556, 1538, 1504, 1392, 1336, 1200, 1116,1057, 980, 803, 707, 666 cm£¾1; MS m/z 199 ([M£¾ H]), 180([M£¾HF]); HRMS Calc.for C13H24F ([M£¾ H]) 199.1993,Found 199.1929.1-Fluoro-1-phenylcyclobutane 2b.Colorless oil; H (CDCl3)1.16¡Ó1.19 (1 H, m), 1.69¡Ó1.80 (1 H, m), 2.02¡Ó2.17 (1 H, m),2.52¡Ó2.74 (3 H, m), 7.30¡Ó7.35 (1 H, m), 7.37¡Ó7.42 (2 H, m),7.46¡Ó7.50 (2 H, m); F (CDCl3) £¾126.8 to £¾127.1 (m); IR 3047,3018, 2970, 1567, 1556, 1538, 1484, 1360, 1270, 1200, 1093, 1036,972, 926, 902, 834, 794, 723, 677, 660 cm£¾1; MS m/z 149 ([M£¾ H]);HRMS Calc. for C10H10F([M£¾ H]) 149.0887, Found 149.0845.Inseparable mixture of 1-( uoromethyl)cyclopropanecarbonitrile 3cand 2-(2-uoroethyl)prop-2-enenitrile 4c.Colorless oil; H (CDCl3)1.08¡Ó1.11 (16/9 H, m), 1.39¡Ó1.42 (16/9 H, m), 2.50 (2/9 H, dt, JHF25.0, JHH 6.0), 4.34 (16/9 H, d, JHF 47.0), 4.62 (2/9 H, dt, JHF 47.0,JHH 6.0 Hz), 5.88 (1/9 H, s), 6.01 (1/9 H, s); F (CDCl3) £¾212.09(8/9 F, t, J 47.0), £¾220.15 (1/9 F, tt, J 47.0 and 25.0 Hz); IR 2970,2248, 1654, 1617, 1435, 1387, 1289, 1041, 1010 cm£¾1; MS m/z 100([M H]); 79 ([M£¾ HF]).Methyl 1-( uoromethyl )cyclopropanecarboxylate 3d.Colorlessoil; H (CDCl3) 0.99¡Ó1.00 (2 H, m), 1.37¡Ó1.38 (2 H, m), 3.73 (3 H,s), 4.52 (2 H, d, JHF 49.0 Hz); F (CDCl3) £¾213.10 (t, J 49.0 Hz);IR 2956, 1732, 1438, 1356, 1283, 1248, 1200, 1167, 1003, 755 cm£¾1;MS m/z 133 ([M H]), 132 (M), 113 ([M£¾ F]); HRMS Calc.for C6H9O2F (M) 132.0586, Found 132.0584.1-(Fluorodiphenylmethyl )cyclopropanecarbonitrile 3e.Colorlessoil; H (CDCl3) 1.25¡Ó1.30 (2 H, m), 1.42¡Ó1.46 (2 H, m), 7.19¡Ó7.45(10 H, m); F (CDCl3) £¾142.90 (s); IR 2926, 2240, 1780, 1654, 1600,1493, 1449, 1277, 1191, 1078, 1049, 1011, 752, 700 cm£¾1; MS m/z251 (M); HRMS Calc.for C17H14FN (M) 251.1092, Found251.1116.1-Fluoro-3,3-diphenylcyclobutanecarbonitrile 2f.Colorless oil; H(CDCl3) 3.34¡Ó3.43 (2 H, m), 3.61¡Ó3.68 (2 H, m), 7.16¡Ó7.37 (10 H,m); F (CDCl3) £¾143.91 to 144.17 (m); IR 3854, 3752, 3736, 3712,3676, 3650, 3630, 3023, 2362, 1719, 1654, 1597, 1491, 1447, 1415,1236, 1120, 1075, 1025, 928, 756, 701 cm£¾1; MS m/z 251 (M);HRMS Calc.for C17H14FN (M) 251.1092, Found 251.1085.2-(2-Fluoro-2,2-diphenylethyl )prop-2-enenitrile 4f.Colorless crys-tals; mp 101¡Ó102 8C; H (CDCl3) 3.32 (2 H, d, JHF 23.0), 5.69 (1 H,s), 5.94 (1 H, s), 7.30¡Ó7.40 (10 H, m); F (CDCl3) £¾148.74 (t,J 23.0 Hz); IR 3104, 3053, 2231, 1913, 1600, 1497, 1451, 1326, 1250,1211, 1057, 1038, 1015, 982, 958, 910, 871, 770, 774, 704, 668 cm£¾1;MS m/z 251 (M); HRMS Calc. for C17H14FN (M) 251.1092,Found 251.1187.This work was supported in part by the Foundation forthe Promotion of Higher Education in Toyama Prefectureand Grant-in-Aid (No. 09771900) for Scientic Researchfrom the Ministry of Education, Science, Sports andCulture, Japan.Received, 23rd June 1998; Accepted, 25th June 1998Paper E/8/04786CReferences1 O. A. Mascaretti, Aldrichim. Acta, 1993, 26, 47; J. A. Wilkinson,Chem. Rev., 1992, 92, 505.2 M. Hudlicky, Org. React. (N.Y.), 1988, 35, 513.3 J.R. McCarthy, N. P. Peet, M. E. LeTourneau andM. Inbasekaran, J. Am. Chem. Soc., 1985, 107, 735.4 S. F. Wnuk and M. J. Robins, J. Am. Chem. Soc., 1990, 55,4757.5 Y. Kikugawa, K. Matsumoto, K. Mitsui and T. Sakamoto,J. Chem. Soc., Chem. Commun., 1992, 921.6 G. Neef, G. Ast, G.,Tetrahedron Lett., 1994, 35, 8587.7 M. Kuroboshi, S. Furuta and T. Hiyama, Tetrahedron Lett.,1995, 36, 6121.8 A. J. Ratclie and I. Warner, Tetrahedron Lett., 1995, 36, 3881.9 S. Bildstein, J. Ducep, D. Jacobi and P. Zimmermann,Tetrahedron Lett., 1996, 37, 4941.10 S. Bildstein, J. Ducep and D. Jacobi, Tetrahedron Lett., 1996,37, 8759.11 M. Kirihara, T. Kambayashi and T. Momose, Chem. Commun.,1996, 1103.12 D. Haigh, L. J. Jefcott, K. Magee and H. McNab, J. Chem.Soc., Perkin Trans. 1, 1996, 2895.13 M. Kirihara, K. Niimi and T. Momose, Chem. Commun., 1997,599.14 P. Borrachero-Moya, F. Cabrera-Escribano, M. Go mez-Guille nand F. Madrir-D az, Tetrahedron Lett., 1997, 38, 1231.15 J. M. Box, L. M. Harwood and R. C. Whitehead, Synlett, 1997,571.16 G. A. Olah, V. P. Reddy and G. K. S. Prakash, Chem. Rev.,1992, 92, 69.J. CHEM. RESEARCH (S), 1998 653

ISSN:0308-2342    

DOI:10.1039/a804786c

出版商:RSC    

年代:1998

数据来源: RSC