Stereospecificity of the Au(I)-catalyzed reaction of 1-alkynyl-bicyclo[4.1.0]-heptan-2-ones with nucleophiles
摘要:
The stereospecificity of the Au(I)-catalyzed reaction of 1-alkynyl-bicyclo[4.1.0]-heptan-2-ones with nucleophiles was investigated. The substrates were prepared in non-racemic form (up to 88% ee) through parallel kinetic resolution (CBS reduction) and reoxidation of the separated diastereomeric alcohols. The key Au-catalyzed reaction was then found to proceed without significant loss of absolute stereochemical information: this way, an achiral carbocationic intermediate could be excluded. Thus, a bicyclobutonium-type intermediate seems to be attacked in a S(N)2-type fashion by the nucleophile in accordance with computational predictions. (C) 2010 Elsevier Ltd. All rights reserved.
The stereospecificity of the Au(I)-catalyzed reaction of 1-alkynyl-bicyclo[4.1.0]-heptan-2-ones with nucleophiles was investigated. The substrates were prepared in non-racemic form (up to 88% ee) through parallel kinetic resolution (CBS reduction) and reoxidation of the separated diastereomeric alcohols. The key Au-catalyzed reaction was then found to proceed without significant loss of absolute stereochemical information: this way, an achiral carbocationic intermediate could be excluded. Thus, a bicyclobutonium-type intermediate seems to be attacked in a S(N)2-type fashion by the nucleophile in accordance with computational predictions. (C) 2010 Elsevier Ltd. All rights reserved.
An efficient synthesis of highly substituted furans via the electrophilic cyclization of 1-(1-alkynyl)-cyclopropyl ketones
作者:Xian Huang、Weijun Fu、Maozhong Miao
DOI:10.1016/j.tetlet.2008.02.081
日期:2008.4
The electrophiliccyclization of 1-(1-alkynyl)-cyclopropyl ketones offers an efficient and straightforward route to highly substituted furans under extremely mild reaction conditions. Iodine, NIS, and PhSeBr have proven successful as electrophiles in this process.