An efficient synthesis of N1-substituted 2,5-dioxo-1,2,5,6,7,8-hexahydro-3-quinolinecarboxamide via enolate salts

Various 2-(2-cyano-2-carbamoyl-1-ethenyl)-5,5-dimethyl-3-oxo-1-cyclohexen-1-olates substituted in the amide group with dialkylammonium or sodium cations were prepared via reactions of N-substituted cyanoacetamides with dimedone–DMFDMA adduct by a one-pot, two-step protocol. The salts obtained were used in reactions with N-nucleophiles for further synthesis of the N1-substituted 2,5-dioxo-1,2,5,6,7,8-hexahydro-3-quinolinecarboxamides that are analogues of well-known pharmaceuticals. The structure of the salts and the N1-substituted 2,5-dioxo-1,2,5,6,7,8-hexahydro-3-quinolinecarboxamides was established by means of spectroscopic and X-ray diffraction studies.