Highly enantioselective organocatalytic sulfa-Michael addition to alpha,beta-unsaturated ketones.
A cinchona alkaloid-derived urea was found to be an efficient organocatalyst for catalyzing enantioselective conjugate addition between thiols and various alpha,beta-unsaturated ketones to provide optically active sulfides with high chemical yields (up to >99%) and enantiomeric excess (up to >99% ee). The reaction was performed with 0.1 mol % of catalyst in toluene at room temperature. A transition state model has been proposed to explain the stereochemical outcome of the reaction.
Rana
Nirmal K
NK
Department of Chemistry, Indian Institute of Technology, Kanpur, India 208 016.
Selvakumar
Sermadurai
S
Singh
Vinod K
VK