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.
描述了 3-
氯-5-(4,6-二
甲氧基嘧啶-2-基
氨基甲酰基
氨基磺酰基)-
1-甲基吡唑-4-羧酸甲酯(
氟磺隆)的改良合成。该合成法的优点是:(i) 1-甲基-1H-
吡唑-4-羧酸甲酯(1)在
硫酰氯存在下进行一锅
氯化反应,生成 3、(ii) 在温和的反应条件下,利用
四丁基氯化铵将 3-
氯-5-巯基-1-甲基-
1H-吡唑-4-甲酸甲酯 (3) 转化为 3-
氯-1-甲基-5-
氨基磺酰基
吡唑-4-
甲酸甲酯 (4)、(iii) 利用微波辐照使磺酰胺(4)与
氨基甲酸酯(6)缩合。我们努力计算卤磺隆合成过程中所有反应步骤的原子经济性、反应质量效率和 E 因子。步骤 2 和步骤 4 反应的 E 因子值较低,表明与合成过程中的其余步骤相比,这些反应更环保(产生的废物较少)。