Synthesis Study Of Ethyl 2-(3-Chloropyridin-2-yl)-5-Oxopyrazolidine-3-Carboxylate

Chlorantraniliprole, which is a commercial anthranilamide insecticide in 2007, has an excellent activity for chewinginsect especially for rice. It shows no-cross resistance to existing insecticides because of its novel mode of action.Ethyl 2-(3-chloropyridin-2-yl)-5-oxopyrazolidine-3-carboxylate was a key intermediate for synthesizing chlorantraniliprole. Three by-products were found in the synthsis study of ethyl 2-(3-chloropyridin-2-yl)-5-oxopyrazolidine-3-carboxylat, and identified their structures by NMR, MS, XRD. Furthermore, the reaction mechanism was described from the result.A standard curve was described for ethyl 2-(3-chloropyridin-2-yl)-5-oxopyrazol -idine-3-carboxylate by HPLC. R2=0.9999, recovery between 99.5%~100.2% and RSD=0.2% showed a good linear relation.During the optimization, it was found that the yield was better while the ratio of 3-chloro-2-hydrazinylpyridine: diethyl maleate: sodium alcoholate was 1:1.2:1.6 at 60℃. The stable study for the optimized reaction showed that the average yield was 49%, which was appearantly higher than the reference of 40.4%.