Study On The Synthesis And Process Of Penthiopyrad

Penthiopyrad is a novel amide fungicide. In this paper, N-(thiophen-3-yl)-benzamide was synthesized from methyl 3-aminothiophene-2-carboxylate through the process of amino protection, hydrolysis and decarboxylation. Then, N-(thiophen-3-yl)-benzamide reacted with 4-methyl-2-pentanone, followed by hydrogenation, and then taking off the amino protection group, an important intermediate 2-(4-methylpentan-2-yl)thiophen-3-amine(1) was obtained; At the same time, the reaction among ethyl formate, ethyl acetate,dimethylamine and other material could give ethyl 2-((dimethylamino)methylene)-4,4,4-trifluoro-3-oxobutanoate(2). Ethyl 1-methyl-3-(trifluoro-methyl)-1H-pyrazole-4-carboxylate was prepared by the reaction of (2) and methyl hydrazine, then followed by hydrolysis and chloration, we got another intermediate 1-methyl-3-(trifluoromethyl)-1H-pyrazole-4-cabonyl chloride(3). Penthiopyrad was synthesized by the reaction between (1) and (3). The chemical structures of reaction products were characterized by MS,'HNMR. The reaction mechanism of each reaction and the major influencing factors were discussed. The total yield was 45.3%, and the purity of the target product was 98.8%(HPLC).