Heterocycles from heterocycles. - III[1]. 1,3,5-trisubstituted hexahydro-1,3,5-triazines-2-ones from 1,3,5-trisubstituted hexahydro-1,3,5-triazines and organic isocyanates

1,3,5-Triscubstituted hexahydro-1,3,5-trazin-2-ones 3 are easily obtained by the reaction of 1,3,5-trisub-stituted hexahydro-1,3,5-triazines 1 with organic isocyanates 2 . The reaction is believed to occur by the sequential addition to 2 of two molecules of the monomeric N-methyleneamines in thermal equilibrium with 1. Substituent scrambling at the operating temperature (120°) was negligible. The crystal structure of 1,3,5-triphenylhexahydro-1,3,5-triazin-2-one (3a) has been determined by X-ray diffraction methods.