(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(CH 2 CHCH 2 ) and [{(6-Mes)Cu} 2 (μ-OEt)][SiF 5 ], which along with the fluorosilane (EtO) 3 SiF are of relevance to the catalytic cycle.