Stepwise and chemoselective installation of carbon substituents at silicon atoms via monobromination of hydrosilanes

Although organosilicon compounds containing different carbon substituents are ubiquitous in synthetic chemistry, their preparation is challenging. Laboratory synthesis commonly relies on the sequential substitution of tetrachlorosilane or tetraalkoxysilanes, producing complex mixtures that require demanding purification. This arises from limited control over nucleophilic substitution in functionalized silanes containing three or four (identical) leaving groups. Here we introduce an experimentally straightforward and reliable procedure for the preparation of both hetero- and homoleptic silanes using an overlooked monobromination of primary and secondary hydrosilanes. An equimolar amount of elemental bromine converts a Si–H bond into an Si–Br bond without ‘overbromination’. This step also shows exceptional functional-group tolerance to existing substituents at the silicon atom. Unsaturated moieties as well as heteroatom and heteroaryl groups are compatible. When performed in an iterative fashion, multihydrosilanes can be selectively converted into secondary, tertiary and quaternary silanes with two, three or four different carbon substituents in high yields. These functionalized silicon building blocks are relevant to synthetic chemistry as well as applied chemistry materials.