A Dinickel Catalyzed Cyclopropanation without the Formation of a Metal Carbene Intermediate. (23rd November 2020)

• Record Type: Journal Article
• Authors: Maity, Arnab K.; Kalb, Annah E.; Zeller, Matthias; Uyeda, Christopher
• Is Part Of: Angewandte Chemie. Volume 133:Number 4(2021)
• Page Start: 1925
• Page End: 1930
• Publication Date: 2020-11-23
• Subjects: carbenes -- cyclopropane -- homogeneous catalysis -- metal–metal interactions -- nickel; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202011602
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: (NDI)Ni2 catalysts (NDI=naphthyridine‐diimine) promote cyclopropanation reactions of 1, 3‐dienes using (Me3 Si)CHN2 . Mechanistic studies reveal that a metal carbene intermediate is not part of the catalytic cycle. The (NDI)Ni2 (CHSiMe3 ) complex was independently synthesized and found to be unreactive toward dienes. Based on DFT models, we propose an alternative mechanism that begins with a Ni2 ‐mediated coupling of (Me3 Si)CHN2 and the diene. N2 extrusion followed by radical C−C bond formation generates the cyclopropane product. This model reproduces the experimentally observed regioselectivity and diastereoselectivity of the reaction. Abstract : Dinickel complexes catalyze regioselective cyclopropanations of unsymmetrical 1, 3‐dienes using TMSCHN2 . Mechanistic studies suggest that the reaction proceeds by a diazoalkane–diene coupling mechanism and does not require the formation of a dinickel carbene intermediate.