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(1H)-one
and 2-phenylquinolin-4(1H)-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.