B(C₆F₅)₃-Catalyzed Direct Deoxygenative Alkenylation of Ketones with Pinacolborane

This investigation presents an innovative methodology for the direct deoxygenative alkenylation of ketones, utilizing pinacolborane as the reducing agent in the presence of the B(C₆F₅)₃ catalyst. A series of aryl ketones containing different functional groups such as hydroxyl, amino, alkynyl, vinyl, and ester groups were found to be well-tolerated. The efficiency of deoxygenative alkenylation could be notably improved by the addition of catalytic LuCl₃ in some substrates. This transformation has also been nicely applied to the gram-scale late-stage functionalization of pharmacologically significant compounds sertraline and conivaptan. Comprehensive mechanistic investigations have elucidated a plausible reaction pathway that proceeds through sequential carbonyl hydroboration, deboration, and deprotonation processes.