Improved synthesis of key intermediate of herbicide bicyclopyrone
[Aims]To improve the synthetic method of 2-((2-methoxyethoxy)methyl)-6-(trifluoromethyl)pyridine-3-carboxylic acid,a key intermediate for the synthesis of herbicide bicyclopyrone.[Methods]2-((2-Methoxyethoxy)methyl)-6-(trifluoromethyl)pyridine-3-carboxylic acid was synthesized from several cheap and easily available raw materials by etherification,multicomponent tandem reactions and hydrolysis.The conditions of etherification and tandem reaction were optimized.[Results]2-(2-Methoxyethoxy)acetonitrile was obtained with a yield of 91％ by etherification reaction of chloroacetonitrile with 2-methoxyethanol.Ethyl 2-((2-methoxyethoxy)methyl)-6-(trifluoromethyl)pyridine-3-carboxylate in 82％ yield was synthesized by one-pot tandem reaction of etherification product with ethyl 2-bromoacetate,paraformaldehyde and 1,1,1-trifluoroacetone.Hydrolysis of tandem reaction product was processed to give 2-((2-methoxyethoxy)methyl)-6-(trifluoromethyl)pyridine-3-carboxylic acid with a yield of 93％ .The structures of the target compounds were confirmed by 1H NMR and 13C NMR.[Conclusions]This method has simple operation,easy post-treatment and high yield,which is suitable for industrial production.
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