Catalyst-Guided C=Het Hydroarylations by Manganese-Catalyzed Additive-Free C-H Activation.

Expedient hydroarylations of C=Het bonds (Het=heteroatom) were accomplished by user-friendly organometallic C-H activation in a positional-selective manner. The broadly applicable C-H functionalization platform enabled the step-economical transformation of aldehydes, ketones, and imines under additive-free reaction conditions. In contrast to palladium, rhodium, ruthenium, rhenium, iridium, nickel, and cobalt catalysis, solely manganese(I) complexes outcompeted the innate substrate control, clearly highlighting the unique power of manganese(I) C-H activation catalysis.