HETEROCYCLES FROM HETEROCYCLES .3. 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-Trisubstituted hexahydro-1,3,5-triazin-2-ones 3 are easily obtained by the reaction of 1,3,5-trisubstituted 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 degrees) 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.