78978-46-8Relevant academic research and scientific papers
Studies of Heterocyclic Compounds. Part 28. Condensation of 3-Substituted 5-Phenyl-1,2-dithiolylium Salts with 2-Amino-N-heterocycles
Mitchell, James A.,Reid, David H.
, p. 499 - 507 (2007/10/02)
3-Chloro-5-phenyl-1,2-dithiolylium chloride condenses in ethanol with 2-amino-N-heterocycles at the amino-group to yield yellow compounds; in many instances reaction occurs also at the ring nitrogen atom yielding orange compounds. 2-Amino-Δ2-thiazoline, 2-aminothiazole, 2-aminopyridine and its monomethyl derivatives, 2-amino-4,6-dimethylpyridine ,2-aminopyrimidine, and 2-aminobenzimidazole all underwent reaction at the amino-group to give the corresponding yellow 2-(5-phenyl-1,2-dithiol-3-ylidenamino)-N-heterocycles. 2-Amino-Δ2-thiazoline, 2-aminothiazole, 2-aminopyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine,and 2-amino-5-methylpyridine also underwent reaction at the ring nitrogen atom to give in low yield 4,5-dihydro-3-thiobenzoylmethylene-3H -thiazolothiadiazole, 3-thiobenzoylmethylene-3H-thiazolothiadiazole, and 3-thiobenzoylmethylene-3H-pyridothiadiazole and its 7-,6-,and 5-methyl derivatives, respectively,as polar orange compounds.The condensations of 3-methoxy-5-phenyl-1,2-dithiolylium fluorosulphonate with 2-amino-Δ2-thiazoline, 2-aminothiazole, and 2-amino-4-methylpyridine were studied.Condensation of 4-methyl-2-tricloromethylthioaminopyridine with benzoylacetic acid in dimethylformamide in the presence of triethylamine gave 6-methyl-3H-pyridothiadiazol-3-one (main prduct) and 6-methyl-3-benzoylmethylene-3H-pyridothiadiazole.Thionation of the latter with tetraphosphorous decasulphide in pyridine gave 6-methyl-3-thiobenzoylmethylene-3H-pyridothiadiazole.The results of 1H n.m.r. spectral studies, and of X-ray crystallographic studies by other workers, are discussed in relation to the structure of the yellow and the orange series of condesation products.It is proposed that the 3-thiobenzoylmethylene-3H-thiazolothiadiazoles and the 3-thiobenzoylmethylene-3H-pyridothiadiazoles, whose formation involves an S-S -> S-N bond switch, are formed via 3H-6,6aλ4-dithia-1,3-diazapentalenes which are higer energy intermediates or transition states. 3-Chloro-5-phenyl-1,2-dithiolylium chloride condensed with 2,6-diaminopyrimidine in a 2:1 ratio to give an orange and a polar red product for which structures are proposed.
