Preparation of [1, 2, 4]triazoloquinazolinium betaines and molecular rearrangements of putative [1, 2, 4]triazolo[4, 3-a][1, 3, 5]triazinium betaines

3H-10?⁵-[1, 2, 4]Triazolo[4, 3-fl]quinazolin-10-ylium-l-aminides were prepared by treating 1-methyl-1-(4-methylquinazolin-2-yl)-4-(aryl)thiosemicarbazides with dicyclohexylcarbodiimide (DCC); the crystal and molecular structure of one such derivative has been investigated by X-ray crystallography. A quinazolinium-1-olate and a -thiolate analogue of the aminides have also been prepared. 2-(l-Methylhydrazino)-4, 6-dimethyl-l, 3, 5-triazine was synthesised by condensing the free base derived from 1-methyl-l-aminoguanidine sulfate with ethyl TV-acetylacetamidate. A series of thiosemicarbazides was prepared by treating the above hydrazine derivative with isothiocyanates. One-such thiosemicarbazide was treated with DCC to afford a 1, 2, 4, 6-tetraazahexadiene derivative. Thermal reaction of 1-(4, 6-dimethyl-1, 3, 5-triazin-2-yl)-1, 3-dimethyl-4-(phenyl)isothiosemicarbazide gave a product of dimerisation, the structure of which was elucidated by X-ray crystallography.