The Iridium(III)-Catalyzed Direct C(sp(2))- and C(sp(3))-H Alkynylation of 2-Acylimidazoles with Various Alkynyl Bromides: Understanding the Full Catalytic Cycle

摘要

An imidazole moiety was introduced as a removal directing group for carboxylic acid derivatives in the Ir(III)-catalyzed alkynylation of C(sp(2))-H and C(sp(3))-H bonds with various alkynyl bromides, including TIPS- and Ar-substituted alkynyl bromides, and Br-propargyl-silyl ethers. The mechanism was explored in detail by investigating the intermediate produced in each individual step. The structures of six-membered iridacycles that were produced as intermediates were confirmed by X-ray crystallographic analysis and NMR and/or FAB-MS.