An efficient synthesis of 2-(2,2-difluoroethoxy)-6-trifluoromethyl-n-(5,8- dimethoxy-1,2,4-triazolo[1,5-c]pyrimidine-2-yl) benzenesulfonamide: Penoxsulam

摘要

An efficient nine-step synthesis of 2-(2,2-difluoroethoxy)-6- trifluoromethyl-N-(5,8-dimethoxy-1,2,4-triazolo[1,5-c] - pyrimidine-2-yl) benzenesulfonamide has been developed. The starting material 4-nitro-2-(trifluoromethyl)aniline starting material was converted via 2-bromo-4-amino-6-trifluoromethylaniline and 2-bromo-4-acetamido-6- trifluoromethylbenzenesulfonic acid to 2-bromo-6-trilfuoromethylbenzenesulfonic acid. This was then combined with 2-amino-5,8-dimethoxy-1,2,4-triazolo[1.5-c] pyrimidine to give the target molecule. Compared with the reported method, this approach has advantages in its shorter reaction time, milder reaction conditions and easier purifiction. Moreover, the overall yield has been improved to 22.9% which is twice of that of the reported method.