Abstract
(NDI)Ni(2) catalysts (NDI=naphthyridine-diimine) promote cyclopropanation reactions of 1,3-dienes using (Me(3) Si)CHN(2) . Mechanistic studies reveal that a metal carbene intermediate is not part of the catalytic cycle. The (NDI)Ni(2) (CHSiMe(3) ) complex was independently synthesized and found to be unreactive toward dienes. Based on DFT models, we propose an alternative mechanism that begins with a Ni(2) -mediated coupling of (Me(3) Si)CHN(2) and the diene. N(2) extrusion followed by radical C-C bond formation generates the cyclopropane product. This model reproduces the experimentally observed regioselectivity and diastereoselectivity of the reaction.