文献类型：期刊文献

英文题名：Influence of Michael acceptor stereochemistry on intramolecular Morita-Baylis-Hillman reactions

作者：Teng, Wen-Dong[1]; Huang, Rui[1]; Kwong, Cathy Kar-Wing[2]; Shi, Min[1]; Toy, Patrick H.[2]

机构：[1]Univ Hong Kong, Dept Chem, Hong Kong, Hong Kong, Peoples R China;[2]E China Univ Sci & Technol, Sch Chem & Pharmaceut, Shanghai 200237, Peoples R China

年份：2006

卷号：71

期号：1

起止页码：368

外文期刊名：JOURNAL OF ORGANIC CHEMISTRY

收录：;EI(收录号：2006059667962);WOS:【SCI-EXPANDED(收录号:WOS:000234438700052)】；

语种：英文

外文关键词：Catalysis - Catalysts - Isomers - Molecular dynamics - Olefins - Reaction kinetics

摘要：A study of the effect of Michael acceptor stereochemistry on the efficiency of intramolecular Morita-Baylis-Hillman (MBH) reactions has been performed. The reactions were catalyzed by a phosphine, and the reaction substrates studied were enones containing a pendant aldehyde moiety attached at the beta-position of the alkene group. In all cases examined with PPh3 as the catalyst, cyclization substrates possessing (Z)-alkene stereochemistry afforded a much higher yield of the desired product than did the E isomeric substrates under identical reaction conditions. This was also true when a polymer-supported phosphine catalyst was used. While both alkene isomers afforded the same product, in parallel reactions, the Z isomer afforded 2.5-8.5 times higher yield than did the corresponding E isomer. It is proposed that steric effects are a possible source of this dramatic difference in reactivity. Substrates where the beta-substituent is cis to the electron-withdrawing substituent are relatively more accessible to react with the nucleophile catalyst than are their trans counterparts. These findings are expected to be useful in the design of synthetic intermediates, as intramolecular MBH reactions are being increasingly used in the preparation of complex synthetic targets.