Divergent Sequential Reactions of β-(2-Aminophenyl)-α,β- ynones with Malonyl Chloride

A viable one-pot synthesis of challenging 4H-[3,4-c]quinolone- 4,5(6H)-diones by the reaction of β-(2-aminophenyl)-α,β-ynones with ethyl malonyl chloride is described. Their further elaboration in the presence of an excess of 40% methyl amine aqueous solution in EtOH gives the benzo[c][2,7]naphthyridine- 4,5(3H,6H)-diones of pharmacological interest in high yields. The product selectivity control of the divergent sequential condensation/C-annulation/intramolecular transesterification vs condensation/O-annulation/ring opening reactions of β-(2-aminophenyl)- α,β-ynones with malonyl chloride under metal free conditions has been addressed.