Investigation On The Asymmetric Michael Addition Reaction Of β, γ-Unsaturated-α-Keto Esters Catalyzed By Chiral Thioureas

This M.S. dissertation deals with designing and synthesis of new chiral thioureas derived from theα-amino acids. The main work presented in this dissertation is focused on the asymmetric Michael addition reaction catalyzed by the chiral thioureas. The contents are listed as the following:1. With the idea of fine turning catalyst structures, a series of thioureas were prepared fromα-amino acids as starting material. These catalysts were employed to catalyze the asymmetric Michael addition reaction of malononitrile toα,β-unsaturated-α-ketoester producing the multifunctionalized 4H-pyrans. Under mild conditions and lower catalyst loading (5 mol%), moderate yield and good enantioslectivity have been achieved.2. The first asymmetric Michael addition ofα-substituted cyanoketones toβ,γ-unsaturated-α-keto esters catalyzed by novel thiourea-tertiary-amine derived from theα-amino acids has been developed. Using low catalytic loading (2 mol%), excellent yield (up to 96%) and enantioselectivity (up to 96%ee) were obtained. Finally, the synthesized corresponding product was further transformed into the interesting and important bioactive compound of 4-aryl-substituted 1, 4-dihydropyridine in shorter sequences.