Recent new developments on the Michael addition of sulfur and selenium nucleophiles

Recent development of synthetic reactions using the Michael addition of thiols or analogues is described. Nucloephilic attack of thiolate anions to a,p-unsaturated ketones or esters generates enolate anions which are active to perform aldol reaction when the reaction condition is kept away from protic media. High stereo selectivity as well as enantio selectivity is achieved for the Michael/aldol tandem reaction when appropriate reaction conditions are employed. High regioselective Michael addition of thiols to unsymmetric fumaric derivatives is also accomplished and the either of regioisomers is prepared in a highly selective manner. The thio-groups introduced by these reactions serve as a useful precursor of carbon radicals that efficiently undergo cyclization reaction to provide heterocyclic compounds diastereoselectively.