Pincer-(NHC)Mn(I) Complex-Catalyzed Selective α-Alkylation of Ketones and Nitriles Using Unactivated Alkenyl Alcohols

Construction of C-C bonds utilizing challenging alkenyl alcohols employing first-row transition-metal catalysts is an unexplored area. Herein, we report the alpha-alkylation of ketones and nitriles using unactivated alkenyl alcohols as coupling partners in the presence of a phosphine-free pincer-NHC carbene-Mn(I) complex. This catalytic system was highly effective for the alpha-alkylation of a wide variety of ketones and acetonitriles having aromatic, heteroaromatic, and aliphatic units in the presence of several reducible functional groups. The practical applicability and synthetic value of this protocol were demonstrated through gram-scale synthesis, evaluation of green chemistry metrics, and functionalization of alkylated products into important molecules. Several control experiments, kinetic studies, and Hammett studies were carried out to understand the reaction mechanism, which was further supported by density functional theory (DFT) calculations.