Asymmetric Synthesis Of Silicon-Stereogenic Alkynyl Silane

Silicon-stereogenic chiral compounds have received increasing attention due to their wide applications as versatile intermediates in asymmetric synthesis,as well as their potential values in the development of silicon-containing functional materials and pharmaceutics.Currently,the catalytic preparation of silicon-stereogenic organosilanes is largely limited to the desymmetrization of the prochiral dihydrosilanes,dialkylsilanes,and diarylsilanes,and the desymmetrization of dialkynylsilanes is relatively less mentioned in the literature.In the second chapter,we have developed the asymmetric desymmetrization of prochiral dialkylsilanes via transition metal-catalyzed[2+2+2]cycloaddition reaction.Up on optimization,the desired the chiral silicon-stereogenic alkynylsilane could be obtained in excellent yield and good enantioselectivity using Rh（cod）₂BF₄ as the catalyst.Notably,the biphosphine ligand SPSi P possessing a large dihedral angle was identified as the optimal ligand,which has been developed by our group.Preliminary studies indicate that this reaction features a good substrate scope and mild reaction conditions.In the third chapter,the preparation of Si-stereogenic alkynylsilanes via asymmetric Sonogashira coupling reaction with a Cu/Pd bimetallic catalysis was investigated.By systematically optimizing the reaction conditions,76%ee of the desired product was obtained with a bi-oxazoline ligand.The preliminary mechanistic studies unveiled that the ee value of the mono-product could be raised along with the formation of more di-product,which indicates a further kinetic resolution process was existed in our catalytic system.