Studies on β-ketoanilides: Synthesis of some new isoquinoline, pyrimido [4,5-c] isoquinoline and phenanthridine derivatives

The β-ketoanilides 1a,b or 2a,b react with the activated nitriles 3a-c to give the isoquinoline derivatives 4a-e, respectively. The pyrimido (4,5-c) isoquinoline derivatives 5a,b and 6a,b were obtained by the reaction of 4a,b with carbon disulfide and/or formamide/formic acid. The phenanthridine derivatives 10 and 11 were produced by cyclization of 1a or 2a with PPA and/or POCl₃ whereas the phenanthridine derivative 13 is obtained by the action of amm. acetate on 12 which is obtained from the reaction of 1a or 2a with m-cresol in the presence of PPA. The structures of the compounds have been confirmed by their IR, ¹H NMR and mass spectral data.