Nickel-Catalyzed Reductive Carboxylation of Styrenes Using CO2

Abstract

A nickel-catalyzed reductive carboxylation of styrenes using CO₂ has been developed. The reaction proceeds under mild conditions using diethylzinc as the reductant. Preliminary data suggests the mechanism involves two discrete nickel-mediated catalytic cycles, the first involving a catalyzed hydrozincation of the alkene followed by a second, slower nickel-catalyzed carboxylation of the in situ formed organozinc reagent. Importantly, the catalyst system is very robust and will fixate CO₂ in good yield even if exposed to only an equimolar amount introduced into the headspace above the reaction.