Reductive Cyclopropanations Catalyzed by Dinuclear Nickel Complexes

Dinuclear Ni complexes supported by naphthyridine-diimine (NDI) ligands catalyze the reductive cyclopropanation of alkenes with CH2Cl2 as the methylene source. The use of mild terminal reductants (Zn or Et2Zn) confers significant functional-group tolerance, and the catalyst accommodates structurally and electronically diverse alkenes. Mononickel catalysts bearing related Nchelates afford comparatively low cyclopropane yields (20%). These results constitute an entry into catalytic carbene transformations from oxidized methylene precursors.