Expedient Synthesis of KetonesviaN-HeterocyclicCarbene/Nickel-Catalyzed Redox-EconomicalCoupling of Alcohols and Alkynes†

Summary of main observation and conclusion AnN-heterocyclic carbene/nickel-catalyzed direct coupling of alcohols and internal alkynes to form alpha-branched ketones has been developed. This methodology provides a new approach to afford branched ketones, which are difficult to access through the hydroacylation of simple internal alkenes with aldehydes. This redox-neutral and redox-economical coupling is free from any oxidative or reductive additives as well as stoichiometric byproducts. These reactions convert both benzylic and aliphatic alcohols and alkynes, two basic feedstock chemicals, into various alpha-branched ketones in a single chemical step.