Novel and convenient synthesis of 4(1H)quinolones

A rapid two-step synthesis of 4(1H)quinolones is described. The first step involves condensation of o-nitroacetophenone with N,N-dimethylformamide dimethylacetal yielding highly crystalline enamines. In the second step a reductive cyclization is achieved under catalytic transfer hydrogenation (CTH) conditions. In all cases, the total time of this process was less than 3 h.