Copper-mediated reactions of Boron-Element-Compounds: Mechanistic Investigations and Catalytic Applications

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Copper-catalysed transfer reaction of nucleophilic Silicon moieties from element-boron-compounds onto organic substrates are a currently intensively studied group of reactions. These reactions are versatile tools in the synthesis of silicon-containing building-blocks. Recently, several groups reported various copper-catalysed transfer reaction of silicon moieties from boronic acid derivatives onto electrophiles such as aldehydes, alpha, beta-unsaturated carbonyl compounds, allyl chlorids, etc. Despite the similarity of these reactions surprisingly different catalytic-systems have been used. The used catalytic systems may be formally classified into three groups: NHC-copper complexes, phosphan-copper complexes and copper(I) cyanide based systems. Only for the NHC-copper system first mechanistic studies have been reported recently by the applicant.This proposal aims to continue the mechanistic investigation on the NHC-copper systems and moreover extend the mechanistic investigations to the copper(I) cyanide based systems.The gained mechanistic understanding will be used to develop novel NHC-copper complex catalysed transformation of boron-element compounds of group 14. elements. The main focus will be on the extension of the silyl-group transfer reaction to new organic substrates, especially less activated carbonyl compounds (e. g. ketones, esters) and the extension of the scope of the method to other synthetically interesting, previously not used, boron-element compounds. Especially boron-element compounds of carbon are of great synthetic interest. The development of such carbon-element coupling reactions (C-C, C-Si, C-Sn, etc.) should provide a valuable extension to the synthetic chemists tool box.