Synthetic Process Improvement Of Carfentrazone-ethyl & Synthesis Of Thiophenes Catalyzed By Lewis Acid

Carfentrazone-ethyl, one of the triazolinone herbicides, was developed by the FMC company in 1990. Because of its safety, low dose, wide crop, carfentrazone-ethyl caused great interest in the agricultural sector and pesticide manufacturers. But now carfentrazone-ethyl synthetic technology is immaturity. Many synthetic difficulties yet to be resolved. We find a suitable synthetic carfentrazone-ethyl process for industrial production by optimizing route and exploring the conditions.In chapter one, we have improved the method for the synthesis of Carfentrazone-ethyl by using 4-chloro-2-fluoro aniline as raw material through nine steps. This method uses the "one-pot" synthesis of the key intermediate triazolinone, amide compound was synthesized by Meerwein arylation reaction, carfentrazone-ethyl was synthesized by amide compound finally. This method was reported for the first time. In this paper, the target compounds and important intermediates were characterized by IR, 1HNMR, LC-MS, and each reaction mechanism and main factors affecting yield were discussed. The target compounds was synthesized successfully with 30.9% overall yield(with the starting 4-chloro-2-fluoroaniline meter), and purity of 99.3%(HPLC normalized content). The process optimizated the reaction conditions(temperature, solvent, the type and amount of the catalyst), improved the yield of the reaction, shortened the reaction time. The process shows fascinating properties such as the mature synthetic technology, simple manufacturing process, easy available raw material, and suitable for scale-up production.The thiophene core is an important privileged heterocyclic scaffold in numerous biologically active pharmacophores and natural products. Although the reported approaches are useful tools for the synthesis of thiophene derivatives, most of them suffer from significant limitations such as the utilization of elemental sulfur, harsh reaction conditions, expensive catalysts, and multistep syntheses or difficult purification. Therefore, the exploration of more general, efficient, rapid, and viable routes is very desirable.The second chapter we based on unique structure of β-oxodithioesters and vinyl azide. A new process has been developed for synthesis of thiophene derivatives catalyzed by Lewis acid. By comparing the impacts on reaction of different kinds of solvents, catalysts and temperature along with various dosages of catalyst, proceeding in toluene catalyzed by InCl3 was found the optimal condition. The synthesized compounds were characterized by IR, 1H NMR, 13 C NMR, HRMS spectra. We obtained single crystals of compound a-1 to determine their precise configurations. Additionally, a plausible mechanism of the reaction is proposed.