HETEROCYCLES FROM HETEROCYCLES. 1,3-DIARYL-4,5-IMIDAZOLIDINEDIONES FROM 1,3,5-TRIARYLHEXAHYDRO-1,3,5-TRIAZINES AND OXALYL CHLORIDE

1,3-Diaryl-4,5-imidazolidinediones ( 6 ) are easily synthesized from 1 ,3,5-triarylhexahydro-1,3,5-triazines ( 1 ) and oxalyl chloride ( 5 ) in a reaction not likely to involve the zwitterionic intermediate ( 3 ) of the N-methylenearylamine dimer, but viewing the sequential pick u p of two units of the monomer ( 2 ) by oxalyl chloride ( 5 ). The esse ntial role of ethyl alcohol added to the reaction mixture is recognize d. Reaction conditions have been optimized and some ten imidazolidined iones ( 6 ) were prepared in good to excellent yields. Geometric param eters of 6 were obtained by X-ray diffraction analysis: all the nuclei are found almost in one plane except for a small twist of the phenyl rings about the C-N bond.