Studies with quinolines:: New synthetic routes to 4H,5H,6H,9H-benzo[ij]pyrano[2,3-b]quinolizine-8-one, 4H-pyrano[2,3-b]pyridine, 2H-pyran-2-one and pyranopyridoquinoline derivatives

Several new benzo[ij]pyrano[2,3-b]quinolizine-8-ones 5 and 4H-pyrano[2,3-b,jpyridine 8 derivatives were synthesized from 4-hydroxyquinolines 1. Reacting 3-acetyl-4-hydroxy-1-phenyl-1H-quinoline-2-one with dimethylformamide dimethylacetal afforded 3-(3-Dimethylamino-acryloyl)-4-hydroxy-1-phenyl-1H-quinolin-2-one 9. This reacted with hippuric acid and diethyl 3-oxoglutarate to give 2H-pyran-2-one 13 and pyranopyridoquinoline 17 respectively.