Manganese Complex-Catalyzed (De)hydrogenative Cyclization toward the Selective Synthesis of 2-Substituted and 2,3-Disubstituted 4-Quinolones.

Herein, we describe bifunctional NNO-Mn(I)-catalyzed switchable synthesis of 3-benzyl-2-phenylquinolin-4(1)-one and 2-phenylquinolin-4(1)-one and their derivatives via (de)hydrogenative annulation of a host of alcohols with diverse amino acetophenones. To expand the versatility of our catalytic protocol, we conducted postsynthetic modification featuring bioactive compounds and synthesized 4-quinolones with antibiotic properties. Control and kinetic experiments were carried out to validate the mechanistic analysis, demonstrating that C-alkylation is preferred over N-alkylation in the synthesis of both heterocycles.