Fluoroboric acid adsorbed on silica-gel (HBF4–SiO2) as a new, highly efficient and reusable heterogeneous catalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds
作者:Gaurav Sharma、Raj Kumar、Asit K. Chakraborti
DOI:10.1016/j.tetlet.2008.04.144
日期:2008.6
found to be a new and highly efficient heterogeneouscatalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds under solvent-free conditions. In the case of 1,3-diaryl-2-propenones, the reactions are best carried out in MeOH. The rate of thia-Michael addition was dependent on the steric hindrance at the β-carbon of the α,β-unsaturated carbonyl substrate as well as surrounding the thiol
Catalytic carbon–sulfur bond formation by amphoteric vanadyl triflate: exploring with thia-Michael addition, thioacetalization, and transthioacetalization reactions
作者:Chien-Tien Chen、Yow-Dzer Lin、Cheng-Yuan Liu
DOI:10.1016/j.tet.2009.10.012
日期:2009.12
A series of thiols have been examined as protic nucleophiles for Michael-type additions to alpha,beta-unsaturated carbonyls as well as double nucleophilic condensations with aldehydes, ketones, and acetals catalyzed by amphoteric, water-tolerant vanadyl triflate under mild and neutral conditions. The newly developed C-S bond formation protocols were carried out smoothly in good to high yields in a highly chemoselective manner. (C) 2009 Elsevier Ltd. All rights reserved.