Selective Hydrosilylation Of Platinum-Catalyzed Enynoates And Copper-Catalyzed Conjugated Dienes

Organosilicon compounds are important synthetic building blocks in organic chemistry because of their low toxicity,good stability,and propensity to undergo various transformations,which have been widely used in the fields of total synthesis of natural products,organosilicon materials,and functionalized organic molecules.Compared with other known methods for synthesis of organosilicon compounds,transition metal-catalyzed hydrosilation of unsaturated carbon-carbon bonds has emerged as a very attractive synthesis method due to its good atom economy.Although the development of transition-metal catalyzed hydrosilylation has received much attention,the challenges to control high regio-and stereoselective with simple and efficient catalytic systems are still existing.The main contents of this dissertation includes as follows:Ⅰ.Platinum-Catalyzed Selective Hydrosilylation of EnynoatesUnder PtCl2/cy-DPEphos catalytic system,the enynoates reacted with various silanes and selectively afforded the cis-hydrosilylation products with retaining the configuration of alkenyl double bond.Thus,a series of stereospecific 1,3-dienyl silicon compounds were obtained.This method is featured by its high yield,mild reaction conditions,high regioselectivity and stereoselectivity.Ⅱ.Copper-Catalyzed Markovnikov 3,4-Hydrosilylation of 2-Substituted 1,3DienesBased on our interest in copper-catalyzed hydrosilylation of unsaturated carboncarbon bonds,we developed a Markovnikov 3,4-hydrosilylation of 2-substituted 1,3dienes by using cupric stearate/xantphos catalytic system.A wide variety of 2-alkyl-or 2-aryl-substituted 1,3-dienes and trihydrosilanes are tolerated in this reaction.This work provides an efficient approach to access the branched allylsilanes.