2-Alkoxy-3-substituted-4-quinolinols from the thermal reactions of N-phenylketenimines bearing ester groups

Several ketenimines bearing ester groups were prepared and their thermal reactions gave 2-alkoxy-3-substituted-4-quinolinols VIa-e via presumed iminoketene intermediates. Subsequent oxidation of 2-alkoxy-3-(3-methylbut-2-enyl)-4-quinolinols VIc and VId provided pyranoquinolines VIIIa and VIIIb.