One-pot synthesis of thia-Michael products from thio acids, epoxides, and electron-deficient alkenes promoted by a silica gel/Et3N combined catalyst

An efficient method for the one-pot production of thia-Michael adducts using thio acids, epoxides, and electron-deficient alkenes is described. Epoxides quickly underwent nucleophilic ring-opening with thio acids on the silica gel surface at room temperature under solvent-free conditions to yield β-hydroxy thioester intermediates. After addition of an electron-deficient alkene and a catalytic amount of Et3N to the reaction mixture, the β-acyloxy mercaptans were generated in situ and subsequently underwent thia-Michael addition reactions to produce the corresponding adducts in good to excellent yields.