Multiligand Enabled, Copper-Catalyzed Hiyama Coupling of Arylsilanes with Unactivated Secondary Alkyl Halides: Reaction Development and Mechanistic Insights

Abstract

Construction of carbon-carbon bonds is the cornerstone in organic synthesis, and Hiyama coupling is the representatively synthetic approach for the linkages between silyl compounds and organohalides. In the precedent literatures, such couplings are mainly utilized for the bond formations of arylsilanes with sp2-aryl halides, yet Hiyama couplings with sp3-hybridized alkyl halides still remained in scarcity. Copper-catalysis has recently been scrutinized in several important transformations of unactivated secondary alkyl halides, whereas their conversions with organosilanes are far-less developed. Herein, we leverage a multiligand catalysis to offer a solution for the efficient copper-catalyzed Hiyama couplings with such unactivated alkyl halides. Detailed mechanistic studies disclosed that the incorporation of NHC ligand with phenanthroline-copper system would dramatically enhance reaction efficiency, where the copper species with NHC and phenanthroline-type ligands were most likely to be account for the C(sp2)−Si bond activation and C(sp2)−C(sp3) bond formation process, respectively.