Synthesis Of Flumiclorac-pentyl As A New Herbicide

Flumiclorac-pentyl was researched and developed by Sumitomo Chemical.As a kind of Tetrahydrophthalimide Herbicides with high activity,it was used to control the weed in corn and soybean fields.With 4-fluorophenol as raw materials,2-chloro-4-fluoro-5-nitrophenol was synthesized via chlorination,hydroxyl protection with triphosgene, nitration and hydrolyzation,and then reacted with pentyl 2-chloroacetate to get pentyl 2-(2-chloro-4-fluoro-5-nitroph-enoxy)acetate,and finally Flumiclorac-pentyl was obtained via reduction and condensation with 4,5,6,7-tetrahydroisobenzofuran-1,3-dione.The total yield was 32.0%,and the purity of the product was 95.8%.In this paper,the synthesis of pentyl 2-chloroacetate,4,5,6,7tetrahydroisobenz-ofuran-1,3-dione, 2-Chloro-4-fluorophenol,2-chloro-4fluoro-5-nitrophenol, 2-(2-chloro-4-fluoro-5-nitroph-enoxy)acetate,pentyl2(5-amino-2-chloro-4-flu -orophenoxy) acetate and Flumiclorac-pentyl were researched.The reaction conditions were discussed and the optimized conditions were obtained.In the process of preparing 2-(2-chloro-4fluoro-5-nitroph--enox-y) acetate,a new route was designed:2-chloro-4fluorophenol reacted with pentyl 2-chloroacetate directly,then nitration by mix-acid to get 2-(2-chloro-4-fluoro-5-nitroph-enoxy)acetate,the yield was 62.8%,and the purity was 70.5%.Compared with the reported process, hydroxyl protection was avoided,and the preparation process was simplied. The structures of all compounds were confirmed by ~1H NMR,MS and IR.