NHC/Nickel(II)-Catalyzed [3+2] Cross-Dimerization of Unactivated Olefins and Methylenecyclopropanes

Abstract

Cross-dimerization of a methylenecyclopropane (1) and an unactivated alkene (2) with typical hydroalkenylation reactivity was observed for the first time by using a [NHC-Ni(allyl)]BAr^F catalyst (NHC=N-heterocyclic carbene). Results show that the C-C cleavage of 1 did not involve a Ni⁰ oxidative addition, which was crucial in former systems. Thus the method reported here emerges as a complementary method for attaining highly chemo- and regioselective synthesis of methylenecyclopentanes (3) with broad scope. An efficient NHC/Ni^II -catalyzed rearrangement of 1 leads to the convergent synthesis of 3 in the presence of 2.

Keywords: N-heterocyclic carbenes; alkenes; hydroalkenylation; insertion; nickel.