Cyanoacetanilide intermediates in heterocyclic synthesis. Part 7: preparation of some spiro[indoline-3,4′-pyridine] and chromeno[3,4-c]pyridine derivatives

The reaction of cyanoacetanilide derivative 1 with some electrophiles was investigated. Treatment of compound 1 with 2-(2-oxoindol-3-ylidene)malononitrile ( 2a ) under reflux in ethanol in the presence of piperidine afforded the spiro[indoline-3,4′-pyridine] derivative 3 . Under similar conditions, condensation of compound 1 with the analog 2b yielded a spiroindole 4 . Chromeno[3,4- c ]pyridine derivative 6 was obtained by cyclization of chromene derivative 5 with ethyl cyanoacetate. In a similar manner, condensation of compound 5 with cylcohexanone under reflux in ethanol in the presence of sodium acetate furnished chromeno[3,4- c ]quinoline derivative 7 . Compound 1 was condensed with 2-hydroxy-1-naphthaldehyde to yield the benzo[ f ]chromeno derivative 8 . Refluxing of benzochromene derivative 8 with ethyl cyanoacetate in ethanol in the presence of catalytic amount of piperidine produced benzo[ f ]chromeno[3,4- c ]pyridine derivative 9 . The structures of the newly synthesized compounds were confirmed on the basis of analytical and spectral data.