A Novel Catalytic Sulfa-michael Addition/Cyclization Tandem Reaction:Stereoselective Construction Of Cyclic Organosulfur Compounds

Organosulfur compounds are widely used in the fields of pharmaceutical chemistry,material chemistry,agricultural chemistry and chemical industry.As an important constituent of organosulfur compounds,cyclic organosulfur compounds(organosulfur compounds containing ring structure)are frequently present in nature and various biological systems and can also serve as useful synthetic scaffolds to a diverse array of building blocks.Therefore,it is of great significance for the construction of cyclic organosulfur compounds.Sulfa-Michael addition is one of the most classical methods for construction of carbon sulfur bond,which is widely applied in organic synthesis.The tandem cyclization reactions triggered by sulfa-Michael addition can prepare cyclic organosulfur compounds bearing stereocenters efficiently and stereoselectively.However,this kind of reaction always requires the involvement of stoichiometric organosulfur reagents,and the catalytic sulfa-Michael addition/cyclization tandem reaction is less reported.A novel catalytic sulfa-Michael addition/cyclization tandem reaction has been developed in this thesis.Starting from the allyl substituted thioesters as substrates,two important kinds of nitrogen heterocyclic organosulfur compounds were synthesised through a catalytic sulfa-Michael-Aldol tandem sequence.This thesis mainly includes the following aspects:1.We have developed a controllable stereoselective synthesis of pyrrolo[2,1-a]isoquinoline derivatives bearing a sulfur moiety with high diastereoselectivity in a catalytically atom-economic fashion.Both cis and trans-products can be readily prepared in moderate to high yields with excellent diastereoselectivities under the optimized reaction conditions.2.We have developed a ligand-mediated catalytic asymmetric sulfa-Michael addition/cyclization tandem reaction.A wide range of 3,3-disubstituted-quinoline-2,4-dione derivatives incorporating all-carbon quaternary stereocenters could be accessed efficiently in excellent yields and enantioselectivities(up to 97/3 e.r.)in a catalytically atom-economic fashion.