Shuttle HAT for mild alkene transfer hydrofunctionalization

Abstract

Hydrogen atom transfer (HAT) from a metal-hydride is a reliable and powerful method for functionalizing unsaturated C-C bonds in organic synthesis. Cobalt hydrides (Co-H) have garnered significant attention in this field, where the weak Co-H bonds are most commonly generated in a catalytic fashion through a mixture of stoichiometric amounts of peroxide oxidant and silane reductant. Here we show that the reverse process of HAT to an alkene, i.e. hydrogen atom abstraction of a C-H adjacent to a radical, can be leveraged to generate catalytically active Co-H species in an application of shuttle catalysis coined shuttle HAT. This method obviates the need for stoichiometric reductant/oxidant mixtures thereby greatly simplifying the generation of Co-H. To demonstrate the generality of this shuttle HAT platform, five different reaction manifolds are shown, and the reaction can easily be scaled up to 100 mmol.