Asymmetic Mannich Reactions By Amino Acid-Based Thiourea

Asymmetric catalysis includes enzymatic catalysis,metal catalysis and organic small molecule catalysis.Among them,organocatalysis have received great attention in asymmetric synthesis for its enzyme mimic,metal-free,atomatically economic and low toxic characters.The amino acid derived catalyst is an emerging catalytic type in the asymmetric catalytic system of organic small molecule,which has the characteristics of cheap,easy to obtain,environment benign and high selectivity.This paper introduces the thiourea or dipeptide thiourea derived from L-tert-leucine catalyzed asymmetric Mannich reaction of 3,5-diaryloxazolidin-2,4-dione with various aromatic sulfonimides.The main contents include:1.A single amino acid derived thiourea as a catalyst for the Mannich reactionIn this thesis,the organocatalytic Mannich reaction of 3,5-diaryloxazolidin-2,4-dione with various aromatic sulfonimides has been developed by using L-leucine as the basic skeleton derived thiourea as catalyst and 5 ? molecular sieves as additive.A series of Mannich products were readily prepared with excellent diastereo-and enantioselectivity(up to 95% ee and 11:1 dr).2.Dipeptide derived thiourea as a catalyst for the Mannich reactionThe organocatalytic Mannich reaction of 3,5-diaryloxazolidin-2,4-dione with various aromatic sulfonimides has been developed by using L-leucine as the basic skeleton derived dipeptide thiourea as catalyst and 5 ? molecular sieves as additive.A series of Mannich products were readily prepared with excellent diastereo-and enantioselectivity(up to 96% ee and 7.5:1 dr).