1,3,4-Thiadiazoles, 2-amino-, EMME

Benzylthio-l,3,4-thiadiazolo[3,2-a]pyrimidine-6-carboxylate (1131, X = S, R = PhCH2S) was prepared in 45% yield in the reaction of 2-amino-5-benzylthio-l,3,4-thiadiazole and EMME in polyphosphoric acid at 130-150°C for 15 min (87EUP238997). 

Instead of the corresponding cyclized product, only the N-(, 2,4-thiadi-azol-3-yl)aminomethylenemalonate (1133) was obtained in 12% yield from the reaction of 3-amino-5-ethoxycarbonylamino-l,2,4-thiadiazole and EMME in polyphosphoric acid at 110°C for 3 hr (77JHC621). 

Amino-3-methyl-l,2,4-thiadiazole was reacted with EMME in boiling trichlorobenzene to give 1,2,4-thiadiazolo[4,5-a]pyrimidine-6-carboxylate (1132) (59JOC779). 

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