Process optimization and synthesis of 3-(4-fluorophenyl)-4,5-dihydro-N-[4-(trifluoromethyl)phenyl]-4-[5-(trifluoromethyl)-2-pyridyl]-1H-pyrazole-1-carboxamide

被引:4
作者
Renga, JM [1 ]
McLaren, KL [1 ]
Ricks, MJ [1 ]
机构
[1] Dow AgroSci, Discovery Proc Res, Indianapolis, IN 46268 USA
关键词
D O I
10.1021/op025619v
中图分类号
O69 [应用化学];
学科分类号
081704 ;
摘要
A convenient, high-yielding synthesis of the insecticide 3-(4-fluorophenyl)-4,5-dihydro-N-[4-(trifluoromethyl)phenyl]-4-[5- (trifluoromethyl)-2-pyridyl]-1H-pyrazole-1-carboxamide is presented. Attempted methenylation of the 2-pyridylacetophenone, obtained from the alkylation of 4-fluoroacetophenone with 2-chloro-5-trifluoromethylpyridine, under standard Mannich conditions resulted in the formation of a methylene-bridged dimer. In addition, the required 2-pyridylpropenone underwent a rearrangement to an acylhydrazine when subjected to hydrazine in a solvent-dependent process. These side reactions were circumvented by the sequential reaction of bis(dimethylamino)methane, trifluoroacetic acid, hydrazine, and arylisocyanate with the 2-pyridylacetophenone in methylene chloride. This one-pot process for preparing the pyrazoline-1-carboxamide enabled rapid and economical scale-up for field and toxicological studies.
引用
收藏
页码:267 / 271
页数:5
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