2-BUTENOIC ACID, 4-((5-ETHYL-1,3,4-THIADIAZOL-2-YL)AMINO)-4-OXO-, METHYL ESTER 4-((5-Ethyl-1,3,4-thiadiazol-2-yl)amino)-4-oxo-2-butenoic acid methyl ester 90278-99-2