Zinc phthalocyanine as an efficient catalyst for halogen-free synthesis of formamides from amines via carbon dioxide hydrosilylation under mild conditions

Abstract

The combination of a zinc phthalocyanine (ZnPc) catalyst and a stoichiometric amount of dimethyl formamide (DMF) provided a simple route to formamide derivatives from amines, CO2, and hydrosilanes under mild conditions. We deduced that formation of an active zinc-hydrogen (Zn-H) species promoted hydride transfer from the hydrosilane to CO2. The cooperative activation of the Lewis acidic ZnPc by strongly polar DMF, led to formation of activated amines and hydrosilanes, which promoted the chemical reduction of CO2. Consequently, the binary ZnPc/DMF catalytic system showed excellent yields and superior chemoselectivity, representing a simple and sustainable pathway for the reductive transformation of CO2 into valuable chemicals as an alternative to conventional halogen-containing process.