Study On Reductive Silylation Of Aryl Carbonyl Compounds

Dearomatic reaction is one of the fundamental transformations in organic syntheses,which bridges aromatic and nonaromatic cyclic compounds.The Birch reduction reaction is one of the most common dearomatization reactions,however,harsh reaction conditions that require alkali metals and liquid ammonia limit the broad usage.On this basis,it is meaningful to use chlorosilane as electrophilic reagent to convert simple aromatic rings into silicon substi-tuted cyclohexene products under mild conditions in ordinary solvents with cheap reagents and safe conditions.Nevertheless,such reactions were unsuccessful when aryl carbonyl compounds were used,due to the strong preference for benzyl silylation.To turn around the present sound site selectivity from the perspective of mechanism,a dianion intermediate looks possible but impractical considering its extremely high energy and unusual formation method.Herein,we construct five-coordinated silicon dianion intermediate directly from aryl carbonyl compounds,magnesium and chlorotrimethylsilane(TMSCl)with N-Methyl-2-pyrrolidone(NMP),and present a general dearomatic silylation of aryl carbonyl compounds under mild conditions.We conduct in-depth study on the mechanism by means of mechanistic experiments and computational chemistry.The results show that the relative reduction potentials of the substrate and NMP/TMSCl adduct,as well as the electronic and steric effects of substituents in the substrate,determine the proportion of dearomatization reactions in this system.In addition,we design a novel electron-transfer catalytic system to realize the dearomatization silylation of diarylketone substrates that are not suitable for the aforementioned system,and propose the mechanism by UV-VIS spectroscopy and mechanistic experiments analyses.We also investigate various transformations of the products,which demonstrate the great potential of the dearomatization silylation reaction developed in this thesis.