NEW STRATEGIES FOR CATALYTIC C-H AND OLEFIN HYDROSILYLATION

Abstract

In the works described here, new catalytic hydrosilylation strategies were explored. First, a highly selective, bond functionalization strategy, achieved via relay of two transition metal catalysts and use of traceless acetal directing groups, was introduced. Specifically, this approach involves the relay of Ir-catalyzed hydrosilylation and Rh-catalyzed ortho-C–H silylation. This acetal directing group strategy was used for catalytic ortho-C–H silylation of phenols and benzoate esters derivatives. Additionally, we developed a transition metal free, catalytic vinyl arenes hydrosilylation method. We describe our discovery on unprecedented, sustainable HAT process and report a mechanism involving Lewis base-catalyzed, complexation-induced HAT (LBCI-HAT), followed by highly selective cross-radical coupling. In this reaction, earth abundant, alkali metal Lewis base catalysts play a dual-role. They first served as a HAT initiator and subsequently a silyl radical protecting group for selective downstream processe. This efficient, and sustainable HAT permits highly controlled access to either branch-selective hydrosilylation or polymerization of vinylarenes.