The Iridium(III)-Catalyzed Direct C(sp<sup>2</sup>)– and C(sp<sup>3</sup>)–H Alkynylation of 2-Acylimidazoles with Various Alkynyl Bromides: Understanding the Full Catalytic Cycle
Sanjit K. Mahato, Naoto Chatani
Abstract
An imidazole moiety was introduced as a removal directing group for carboxylic acid derivatives in the Ir(III)-catalyzed alkynylation of C(sp2)–H and C(sp3)–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.
Topics & Concepts
IridiumChemistryCatalysisMoietyPropargylMedicinal chemistrySilylationAlkynylationCatalytic cycleAlkyneImidazoleStereochemistryOrganic chemistryCatalytic C–H Functionalization MethodsCatalytic Cross-Coupling ReactionsSynthesis and Catalytic Reactions