Evaluation of Synthesis of Methyl 3-Chloro-5-(4,6-dimethoxypyrimidin- 2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate Using Green Metrics

Abstract

A modified synthesis of methyl 3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate (halosulphuron) is described. The merits of the synthesis are (i) one pot chlorination of methyl 1-methyl-1H-pyrazole-4-carboxylate (1) in presence of sulphuryl chloride resulting in methyl 3,5-dichloro-1-methyl-1H-pyrazole-4-carboxylate (2) (ii) conversion of 3-chloro-5-mercapto-1-methyl-1H-pyrazole-4-carboxylate (3) to 3-chloro-1-methyl-5-sulfamoyl pyrazole-4-carboxylate (4) under mild reaction conditions utilizing tetrabutyl ammonium chloride, N-chlorosuccinimide and ammonium carbonate (iii) condensation of sulphonamide (4) with carbamate (6) by microwave irradiation. Efforts were made to calculate, atom economy, reaction mass efficiency and E-factor for all the reaction steps involved in the synthesis of halosulfuron. The E-factor values in step 2 and step 4 reaction is lower, indicating that these reactions are greener (generation of less waste) when compared to the remaining steps in the synthesis.

Discovery of ortho-Alkoxy Substituted Novel Sulfonylurea Compounds That Display Strong Herbicidal Activity against Monocotyledon Grasses

“…The synthesis of these compounds is basically according to a published method. , After 3 (50 mmol) was dissolved in tetrahydrofuran (THF, 80 mL), potassium carbonate (11.7g, 84 mmol) was added to the mixture. Then, phenyl carbonochloridate (9.4 mL, 50 mmol) was added to the reactants, and the mixture was stirred for 18 h at room temperature.…”