4-Hydroxy-2-quinolones. 97. Simple synthesis of the esters of 4-halo-substituted 2-oxo-1,2-dihydroquinoline-3-carboxylic acids

Article abstract of DOI:10.1007/s10593-006-0174-3

Short term treatment of 3-ethoxycarbonyl-4-morpholino-2-oxo-1,2- dihydroquinoline with aqueous solutions of hydrohalogen acids leads to the formation of the ethyl esters of 4-halo-substituted 2-oxo-1,2-dihydroquinoline- 3-carboxylic acids. Hydrolysis in HF is possible on extended boiling only to the 4-hydroxy derivative.