Reaction of 2‐dimethylaminomethylene‐1,3‐diones with dinucleophiles. V. Synthesis of 5‐acyl‐1,2‐dihydro‐2‐oxo‐3‐pyridinecarbonitriles and 1,2,5,6,7,8‐hexahydro‐2,5‐dioxo‐3‐quinolinecarboxamides

The reaction of open-chain sym-2-dimethylaminomethylene-1,3-diones Ia-d with sodium cyanoacetamide gave, generally in good yields, 6-substituted 5-acyl-1,2-dihydro-2-oxo-3-pyridinecarbonitriles IIa-d, whereas cyclohexane sym-2-dimethylaminomethylene-1,3-diones Ie-h afforded in general a mixture of 1,2,5,6,7,8-hexahydro-2,5-dioxo-3-quinolinecarbonitriles and 5,6,7,8-tetrahydro-2,5-dioxo-2H-1-benzopyran-3-carboxamides, the latter being isolated in two cases. The reaction of Ie-h with cyanoacetamide in refluxing anhydrous ethanol gave 1,2,5,6,7,8-hexahydro-2,5-dioxo-3-quinolinecarboxamides IIIe-h in excellent yields, whereas Ia-d did not react with the exception of Ia which afforded in good yield 3-pyridinecarboxamide IlIa. Other 3-pyridine-carboxamides were obtained by partial hydrolysis of nitriles IIb,d. 3-Pyridine and 3-quinoline carboxamides were hydrolyzed in satisfactory yields with hydrochloric acid to the corresponding carboxylic acids, which were decarboxylated in good yields to 5-acyl-2(1H)-pyridinones and 7,8-dihydro-2,5(1H,6H)-quinolinediones, respectively, by reflux in quinoline containing a catalytic amount of copper powder.