2-(吡啶-3-基)-2H-吲唑-4-羧酸的新合成方法

Novel synthesis method of 2-(pyridin-3-yl)-2H-indazole-4-carboxylic acid

[目的]开发杀虫剂indazapyroxamet中间体2-(吡啶-3-基)-2H-吲唑-4-羧酸的新合成路线。[方法]从2-甲基-3-硝基溴苯出发,经过甲基氧化、缩合等过程得到邻硝基亚胺中间体,以三正丁基膦还原环化得到关键的2H-吲唑母核。随后经过插羰反应和水解反应得到2-(吡啶-3-基)-2H-吲唑-4-羧酸。[结果]整条路线有5步反应,总收率47%。[结论]该路线新颖、原材料易得、条件温和、收率高,避免了使用危险的叠氮化钠,适于工业化生产,也为该类新农药的创制提供了有力的技术支持。

[Aims]This study aims to develop a new route to synthesize intermediate of indazapyroxamet,2-(pyridin-3-yl)-2H-indazole-4-carboxylic acid.[Methods]Commercially available 1-bromo-2-methyl-3-nitrobenzene was used as the raw material to afford ortho-imino-nitrobenzene products via methyl oxidation and condensation.2H-indazoles framework was synthesized undergoing reductive cyclization promoted by tributyl phosphine,then 2-(pyridin-3-yl)-2H-indazole-4-carboxylic acid was obtained through palladium-catalyzed carbonylation and hydrolyzation.[Results]An e fficient synthetic approach was developed in 5 steps with an overall yield of 47%.[Conclusions]The novel route using commercially available starting materials and mild conditions,resulting in a high yield and avoiding the use of dangerous sodium azide,is convenient for industrial production.This route also provides technical support for research and development of new pesticides of this kind.