Abstract
Reductive ring opening of readily available epoxides provides easy access to synthetically important alcohols. However, controlling the regioselectivity of the reaction under user-friendly conditions remains challenging. Here, we present an efficient methodology for regioselective transfer hydrogenation (TH) of epoxides to synthesize Markovnikov and anti-Markovnikov alcohols using 2-propanol as the hydrogen source. An [IrCl(cod)(NHC)] (cod = 1,5-cyclooctadiene, NHC = N-heterocyclic carbene) complex as a precatalyst enables the formation of secondary and tertiary alcohols in good to excellent yields via selective TH of mono- and 2,2-disubstituted terminal epoxides. Remarkably, we found that an NHC-Ir & Pd/C cooperative catalysis approach can steer the regioselectivity of the reaction to afford anti-Markovnikov alcohols. This cooperative catalysis approach enables the transfer hydrogenative ring opening of mono- and 2,2-disubstituted terminal aryl epoxides to form linear alcohols and challenging internal epoxides to give branched alcohols.