Ir(III)-Catalyzed Mono-Olefination of Aryl C–H Bonds Using −SCF3 as a Weak Directing Group

The trifluoromethylthionyl group (-SCF3) is an efficient weak directing group for Ir(III)-catalyzed aryl C-H olefination. Various trifluoromethylthioethers provide high levels of mono-olefination products in good to excellent yields under mild conditions with a 2,2'-bipyridine ligand or AgBF4 as an additive. Mechanistic studies indicate the C-H cleavage is the rate-determining step. The directing group ability of the -SCF3 group is benchmarked against several other weak directing groups by competition experiments under Ir(III)-catalyzed conditions.