Manganese-catalysed divergent silylation of alkenes

Transition-metal-catalysed, redox-neutral dehydrosilylation of alkenes is a long-standing challenge in organic synthesis, with current methods suffering from low selectivity and narrow scope. In this study, we report a general and simple method for the manganese-catalysed dehydrosilylation and hydrosilylation of alkenes, with Mn2(CO)10 as a catalyst precursor, by using a ligand-tuned metalloradical reactivity strategy. This enables versatility and controllable selectivity with a 1:1 ratio of alkenes and silanes, and the synthetic robustness and practicality of this method are demonstrated using complex alkenes and light olefins. The selectivity of the reaction has been studied using density functional theory calculations, showing the use of an iPrPNP ligand to favour dehydrosilylation, while a JackiePhos ligand favours hydrosilylation. The reaction is redox-neutral and atom-economical, exhibits a broad substrate scope and excellent functional group tolerance, and is suitable for various synthetic applications on a gram scale. Methods for the dehydrosilylation of alkenes typically suffer from low selectivity and narrow scope. Now, the highly selective manganese-catalysed redox-neutral dehydrosilylation and hydrosilylation of alkenes has been achieved through ligand-tuned metalloradical activity. Whereas an electron-rich bidentate ligand promotes dehydrosilylation, hydrosilylation is the favoured pathway when using an electron-deficient phosphine ligand. DFT calculations have been carried out to understand the observed selectivity.