1H and 13C NMR spectral studies of some 4H-3,1-benzoxazin-4-ones and their 2-acylaminobenzoic acid precursors

The 1H and 13C NMR spectra of twelve 4H-3,1-benzoxazine-4-ones and of their acylaminobenzoic acid precursors are presented. Differentiation between these two series of compounds is best achieved through the characteristic J(CH) coupling interactions in the high frequency carbonyl region. Some 4H-pyrido2,3-d]1,3]oxazin-4-ones have also been studied and some earlier literature assignments revised.