抄録
In order to obtain 2, 6-dicyano-7-ethoxycarbonyl-1, 5-dioxo-1, 2, 3, 5-tetrahydroindolizine as an intermediate for the synthesis of camptothecin, Michael condensation of methyl 3-cyano-4-ethoxycarbonyl-1, 2-dihydro-2-oxopyridine-6-carboxylate (V) with acrylonitrile was carried out but failed to afford the objective substance. A similar condensation of V with t-butyl acrylate also resulted in failure. Ethyl 5-cyano-4-ethoxycarbonyl-5-oxo1, 6-dihydro-2-pyridine glyoxylate (VIII) was synthesized by the reaction of 3-cyano-4-ethoxycarbonyl-1, 2-dihydro-2-oxopyridine-6-carboxylic acid chloride with ethyl t-butylmalonate. Although cyclization of VIII to ethyl 6-cyano-1, 2, 3, 5-tetrahydro-1, 3, 5-trioxo-7-indolizine carboxylate (IX) was unsuccessful, Friedlander reaction of VIII with 2-aminobenzaldehyde gave the expected 8-cyano-7-ethoxycarbonyl-9, 11-dihydro-9, 11-dioxoindolizino[1, 2-b]quinoline (X) in one step.
