Structural analysis of 2,3,6-trisubstituted 1,4-dihydro-4-oxoquinolines by means of 13C and 15N NMR spectroscopy
Abstract2,6-Substituted 1,4-dihydro-4-oxoquinoline-3-carboxylic acid ethyl esters were synthesized, and the effect of substituents on the migration of a hydrogen atom from the nitrogen atom to the oxygen atom was studied by 13C and 15N NMR spectroscopy. The presence of a 4-nitrophenylvinyl or 5-nitro-2-furylvinyl system in the 2 position of the compounds stabilizes their 4-oxoquinoline form.