Iminophosphorane-mediated syntheses of [1,2,4]triazolo[5,1-c][1,2,4]triazines. The unexpected formation of Z,Z-1,3-diazetidine-2,4-di-imines. X-Ray molecular structure of 7-(p-chloroanilino)-8-(p-chlorophenyl)-3-methyl[1,2,4]triazolo[5,1-c][1,2,4]triazin-4(8H)-one and of 1,3-bis-(p-chlorophenyl)-2,4-bis-(6-methyl-3-methylthio-5-oxo-4,5-dihydro-1,2,4-triazin-4-ylimino)-1,3-diazetidine

A number of [1,2,4]triazolo[5,1-c][1,2,4]triazine derivatives have been prepared. 6-Methyl-3-methylthio-4-triphenylphosphoranylideneamino-5-oxo-4,5-dihydro-1,2,4-triazine (19) reacts with aryl isocyanates to yield the corresponding 1,3-diaryl-2,4-bis-(6-methyl-3-methylthio-5-oxo-4,5-dihydro-1,2,4-triazin-4-ylimino)-1,3-diazetidines (20)–(24); these undergo ring cleavage on treatment with aqueous ethanol to give the 8-aryl-7-arylamino-3-methyl[1,2,4]triazolo[5,1-c][1,2,4]triazin-4(8H)-ones (8), (12), and (16)–(18). The reaction of the 3-arylmethylenehydrazino-6-methyl-5-oxo-4-triphenylphosphoranylideneamino-4,5-dihydro-1,2,4-triazines (35) and (36), available from the corresponding 4-amino-3-arylmethylenehydrazino-6-methyl-5-oxo-4,5-dihydro-1,2,4-triazine and triphenylphosphine dibromide, with alkyl or aryl isocyanates led directly to 7-arylamino-8-arylmethyleneamino-3-methyl[1,2,4]triazolo[5,1-c][1,2,4]triazin-4(8H)-ones (37)–(46). Also, iminophosphoranes (5)–(7), (35), and (36) react with acyl chlorides in the presence of triethylamine to give the triazolotriazinones (25)–(31) and (50)–(55) respectively. Structures of compounds (20)–(24) have been established by means of 13C n.m.r. analysis and X-ray crystallography.