Keten SS-acetals. Part 10. Reaction of α-oxoketen SS-acetals with N-alkylcyanoacetamides: a new general method for substituted and fused 2,7-dialkyl-8-amino-5-cyano-2,7-naphthyridine-1,6(2H,7H)-diones

Abstract

The reaction of α-oxoketen SS-acetals (1a-j) with N-methyl- and N-ethyl-cyanoacetamide (2a and b) in the presence of sodium isopropoxide gives good yields of 2,7-naphthyridine derivatives (4a-j) and (4k-r) respectively, which are shown to be formed through further reaction of intermediate N-alkylpyridones (3a-r) with anions of either (2a or b). The α-cyanoketen SS-acetals (9a-c), however, gave the corresponding 6-amino-pyridones (10a-f) under similar conditions, whereas cyclic keten SS-acetals (11a and b) yielded the respective fused napthyridines (12a-d) in excellent yields. Keten SS-acetals (15a and b) also react smoothly with (2a and b) to afford novel naphthonaphthyridone derivatives (16a-d) in good yields; the corresponding benzocycloheptanonaphthyridines (16e and f) were similarly obtained under identical conditions by the reaction of (15c) with (2a and b) respectively. α-Alkyl-α-oxoketen SS-acetals (17a-d), however, gave poor yields of pyridones (18a-e) on prolonged refluxing with either (2a or b).