(carbene)CuF Complexes Featuring Bulky Arduengo-Type, Ring-Expanded, and Cyclic (Alkyl)(amino)carbenes: Applications in Catalytic Aldehyde Allylation

Five examples of two-coordinate copper(I) fluoride complexes stabilized by five-, six-, and seven-membered-ring N-heterocyclic carbenes or a cyclic (alkyl)(amino)carbene have been prepared, structurally characterized, and employed in the catalytic allylation of octanal. The very bulky trityl-based carbene ITr affords the most active catalytic system. Mechanistic studies have led to the isolation of (ITr)Cu(CH2CHCH2) and [{(6-Mes)Cu}2(μ-OEt)][SiF5], which along with the fluorosilane (EtO)3SiF are of relevance to the catalytic cycle.