Synthesis Of New Chiral N,N’-Dioxide Derivatives And Their Application For Asymmetric Hydrosilation Reaction

Chiral amine is an important chiral drug intermediate that is widely used in the fields of medicine,food,and fine chemicals.The asymmetric hydrosilation reaction is an effective method for the preparation of chiral amines through asymmetric catalysis.New stereocenters were generated from asymmetric catalysis which reduces different carbon-heteroatom double bonds.In this thesis,L-tryptophan was used as a raw material to design and synthesize a series of chiral epimerized N,N’-dioxide catalysts.According to asymmetric hydrosilation reaction,β-enamino ester and ketimine substrates effectively reduces the C=C and C=N double bonds,and produce chiral amine compounds with high enantioselectivity.The content of this paper is mainly divided into three chapters.The first chapter summarizes the research of asymmetric hydrosilation reactions catalyzed by chiral Lewis base catalysts,and the development and current status of chiral Lewis base catalysts for asymmetric hydrosilation C=N double bond ketimine reaction,C=C double bond β-enamine ester reaction,and C=O double bond ketone reaction are overviewed respectively.In the second chapter,seven novel chiral biscarboline catalysts were synthesized from L-tryptophan,and their catalytic activity was preliminarily investigated in the asymmetric hydrosilation β-enamine ester reaction.The experimental results indicated that chiral biscarboline catalysts own moderate enantioselectivities when(S)-2-(methoxymethyl)-pyrrolidine is attached to C-3,C-3’ bonds.Subsequently,we modified catalysts by nitrogen oxidation and then applied them to the asymmetric hydrosilation reaction of 16 different structures of β-enamine esters.We found that the reaction at-5℃ was completed within 24 h and 1mol% of catalyst usage could achieve high conversion yields to 85%～94% and the enantioselectivity up to 98%ee.In the third chapter,to explore the catalytic activity of the novel chiral N,N’-dioxide catalysts in different types of asymmetric hydrosilation reactions,we tried to apply the obtained chiral N,N’-dioxide catalyst to the asymmetric hydrosilation reaction,it also had an excellent catalytic effect..The result indicated that the reaction which catalyst was applied to14 different ketimines was completed at-10℃ within 24 h.The yields can be 82%～94%,and the enantioselectivity can be high up to 92%ee.