AZOLES AND AZINES. 62. STRUCTURE OF 2-ARYL-1,3-OXAZINE-4,6-DIONES

Article abstract of DOI:10.1007/BF00761994

1H, 13C NMR, IR, and UV spectra have been studied for solutions of a number of potentially tautomeric 2-aryl-1,3-oxazine-4,6-diones and their 5-methyl substituted analogs with variation of substitutent at the para position of the benzene ring, as well as compounds with a fixed structure that simulates possible tautomeric forms.The data have been compared with the results of quantum chemical calculations carried out in SSO MO LCAO approximation by the CNO, CNDO/2, and MPNDO/3 methods.In DMSO and THF solution the test compounds exist predominantly as 2-aryl-4-hydroxy-6H-1,3-oxazin-6-ones.The para substituent in the benzene ring does not effect the composition of the tautomer mixture significantly.