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

来源：

ORGANIC PROCESS RESEARCH & DEVELOPMENT | 2003年 / 7卷 / 03期

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

页码：267 / 271

页数：5