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《Tetrahedron: Asymmetry》2000,11(22):4601-4608
The reaction of phenylpropargyl aldehyde diethyl acetal with 1-phenyl-3,4-dimethylphosphole at 140°C or 1,2,5-triphenylphosphole at 170°C leads, after deprotection, to the corresponding 1-phosphanorbornadiene-2-carboxaldehydes 3 and 4 in 88 and 45% yields, respectively. The resolution of 3 and 4 was carried out by chromatography or fractional crystallization of the acetals derived from (S,S)-1,2-diphenylethane-1,2-diol. The absolute configurations were established by X-ray analysis of one of these acetals or of a 2-bromomethyl derivative. 相似文献
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The Vilsmeier-Haack formylation is the route most frequently employed for the introduction of a formyl group into the 2 or 3 position of a pyrrole ring.2,3 Factors affecting the extent of substitution in the 2 and 3 positions in N-substituted pyrroles under Vilsmeier-Haack conditions have been investigated and the product distribution appears mainly to be the result of steric interactions.4,5 Although it is relatively simple to introduce a formyl residue into the 2-position of a pyrrole nucleus, considerable molecular manipulation must normally be undertaken to prepare pyrrole-3-carboxaldehydes which do not bear substituents in the 2 and 5 positions of the pyrrole ring.6 An alternative method is the generation of isomeric mixtures of pyrrole-2-carboxaldehyde and pyrrole-3-carboxaldehyde by the acid mediated rearrangement of t h e corresponding pyrrole-2-carboxaldehydes. 相似文献
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Koketsu M Mizutani K Ogawa T Takahashi A Ishihara H 《The Journal of organic chemistry》2004,69(25):8938-8941
The reaction of lithium alkyneselenolate with alpha,beta-unsaturated ketone and then alkyl or acyl halide afforded 3-acyl-1-alkyl-2-alkylseleno-1-cyclobutene. The structure of the cyclobutene was elucidated by IR, MS, (1)H, (13)C, and (77)Se NMR, COSY, HMQC, and HMBC data and X-ray analysis. 相似文献
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Bruno Cavalleri Roberto Ballotta Gian Carlo Lancini 《Journal of heterocyclic chemistry》1972,9(5):979-984
We report the preparation of 1-methyl- and 1-ethyl-2-nitroimidazole-5-carboxaldehydes (Ia,b). For Ia three different routes of synthesis are described, which appear of general value for preparing 1-alkyl substituted 2-nitroimidazole-5-carboxaldehydes. 相似文献
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G. A. Golubeva L. A. Sviridova E. S. Besidskii G. S. Besidskaya 《Chemistry of Heterocyclic Compounds》1990,26(4):416-420
Unlike 3-acylindoles, 3-acyl-2-aminoindoles display high selectivity on being electrophilically attacked in the benzene ring, and are substituted at the 6-position. At the same time, an unco-subsitution of the acyl group takes place (to the greatest extent — the formyl group). Direct bromination of 3-acyl- and 3-cyano-2-aminoindoles provides the 6-bromo- and 6,4-dibromo-2-aminoindoles and their derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 486–490, April, 1990. 相似文献
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F. A. Trofimov L. I. Shevchenko T. I. Mukhanova A. N. Grinev 《Chemistry of Heterocyclic Compounds》1977,13(8):835-837
It is demonstrated that, depending on the position of the acetyl substituent in the furan ring of benzofuran, the Schmidt rearrangement leads to benzofuran-2-carboxylic acid methylamide or to 3-acetamidobenzofuran derivatives.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1040–1042, August, 1977. 相似文献
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《合成通讯》2013,43(14):2423-2427
Abstract A facile, two step procedure for the preparation of ethyl 5-iodo-1H-indole-2-carboxylate (1) from commercially available ethyl 1H-indole-2-carboxylate is described herein, employing a regioselective C3, C5-bisiodination followed by zinc-mediated C3-dehalogenation. 相似文献
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While 2-acetyl and 2-benzoyl-3-aminobenzofurans did not react with hydrazine, monomethyl- and N,N-dimethylhydrazine to give the related hydrazones, their 3-N-(p-toluenesulfonyl) derivatives afforded them smoothly in good yields. Depending upon reaction conditions, products arising from hydrazone cyclization to benzofuropyrazoles and/or from furan ring cleavage at the C2 O bond to give 5-(2-hydroxyphenyl)pyrazoles were also formed. The formation of these products depends upon hydrazones configuration and is discussed. Only (E)-isomers appear to undergo furan ring opening. In acidic media at room temprature either the hydrazones or the monomethylhydrazones gave the same related α-azines. Microanalyses, ir, uv, 1H-nmr and ms spectra are in agreement with the proposed structures. 相似文献
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M. A. Yurovskaya V. V. Druzhinina M. A. Tyurekhodzhaeva A. K. Shestakova V. A. Chertkov Yu. G. Bundel' 《Chemistry of Heterocyclic Compounds》1984,20(1):55-58
It has been established on the basis of the results of 1H and 13C NMR, UV, and IR spectroscopy that 3-acyl-2-methylindole oximes each exist in the form of a mixture of two isomers with a predominance of syn-s-trans form. The proportion of the anti form rises (to 25–35%) with an increase in the volume of the alkyl radical in the oxime grouping.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 65–68, January, 1984. 相似文献
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Nair V Sinu CR Rejithamol R Seetha Lakshmi KC Suresh E 《Organic & biomolecular chemistry》2011,9(15):5511-5514
An unexpected transformation of 2H-chromene-3-carboxaldehydes to coumarin derivatives, mediated by NHC, is reported. 相似文献
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T. E. Glotova A. S. Nakhmanovich M. V. Sigalov T. N. Komarova É. I. Kositsina V. Yu. Vitkovskii I. D. Kalikhman 《Russian Chemical Bulletin》1987,36(1):194-196
Conclusions The reaction of 1-acyl-2-phenylacetylenes with thiosemicarbazide in methanol at 60C gives 2-amino-7-hydroxy-6,7-dihydro-1,3,4-thiadiazepines which, upon heating in -vacuum fragment with the formation of 3,5-disubstituted pyrazoles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 216–218, January, 1987. 相似文献
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Furan-, thiophene- and -methylpyrrole-2-carboxaldehydes may be transformed into the corresponding ,'-dimethylimidazolidines in a reaction not requiring acid catalysis. The resulting furan and thiophene (but not -methylpyrrole) derivatives may be metallated in high yields [predominantly at the 5 (α-) positions of the heteroaromatic rings] and the carboxaldehyde functionality regenerated under very mild conditions. Treatment of the aldehydoketone 2-acetyl-5-formylthiophene with ,'-dimethylethylenediamine gives the product of reaction at the aldehyde function thus establishing this methodology as a potentially valuable method for the protection of an aldehyde in the presence of a ketone. 相似文献
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Shuntaro Matakas Masayoshi Kurisu Kazufumi Takahashi Masashi Tashiro 《Journal of heterocyclic chemistry》1985,22(2):325-328
1,2,5-Thiadiazole-3-carboxaldehydes 1a-c were prepared by the acid-catalyzed decomposition of 3-azido-methyl-1,2,5-thiadiazoles 2a-c in 68-83% yields, respectively. Pyrolysis of 2a and 2b afforded the imidazoles 4a and 4b in low yields. NBS -bromination of 1a and 1b gave the corresponding carboxylic acids 10a and 10b via acid bromides 9. Azides 2a and 2b gave the s-triazines 8a and 8b on treatment with NBS. 相似文献