A Dinickel Catalyzed Cyclopropanation without the Formation of a Metal Carbene Intermediate
Arnab K. Maity, Annah E. Kalb, Matthias Zeller, Christopher Uyeda
Abstract
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.
Topics & Concepts
CyclopropanationCarbeneCyclopropaneChemistryCatalysisRegioselectivityMedicinal chemistryDienePhotochemistryStereochemistryOrganic chemistryRing (chemistry)Natural rubberCyclopropane Reaction MechanismsN-Heterocyclic Carbenes in Organic and Inorganic ChemistryCatalytic C–H Functionalization Methods