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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Shapiro reaction ： ウィキペディア英語版 Shapiro reaction The Shapiro reaction or tosylhydrazone decomposition is an organic reaction in which a ketone or aldehyde is converted to an alkene through an intermediate hydrazone in the presence of 2 equivalents of strong base.〔Shapiro, R. H.; Lipton, M.F.; Kolonko, K.J.; Buswell, R.L.; Capuano, L.A. ''Tetrahedron Lett.'', 1975, 1811. 〕〔Shapiro, R. H. ''Org. React.'', 1976, ''23'', 405. (Review)〕〔Adlington, R.M.; Barret, A.G.M. ''Acc. Chem. Res.'', 1983, ''16'', 55. (Review)〕 The reaction was discovered by Robert H. Shapiro in 1967.〔Shapiro, Robert H.; Heath, Marsha J. ''J. Am. Chem. Soc.'', 1967, 89, 5734–5735. 〕 The Shapiro reaction was used in the Nicolaou Taxol total synthesis. ==Reaction mechanism== In a prelude to the actual Shapiro reaction a ketone or an aldehyde is reacted with p-toluenesulfonylhydrazide〔''Organic Syntheses'' Coll. Vol. 5, p.1055 (1973); Vol. 40, p.93 (1960) ((Article ))〕 to a ''p''-toluenesulfonylhydrazone (or tosylhydrazone) which is an imine or hydrazone. Two equivalents of a strong base, such as ''n''-butyllithium, then abstract first the proton from the hydrazone and then the less acidic proton α to the hydrazone carbon, leaving a carbanion. The carbanion proceeds in an elimination reaction to create the carbon–carbon double bond. This step results in expulsion of the tosyl group and formation of a diazonium anion. The anion then collapses, falling off as a neutral nitrogen molecule. The result is a vinyllithium at the position where the nitrogen had been attached. This organolithium carbon is both nucleophilic and basic. It can be reacted with various electrophiles or simply neutralized with water or an acid. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Shapiro reaction」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.