| 摘要 |
<p>Processes for the preparation of the herbicidal sulphonamide azimsulfuron (1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl)pyrazol-5-ylsulfonyl]urea) or its salts, isomers and other derivatives thereof wherein the process involves treating the pyrazole compound of formula (I) wherein R1 is selected from SH, -SCH2Ph, SR or S-SR1; where R is a straight or a branched chain C1-4alkyl and R1 is a group of formula (II) where * donates the point of attachment; with aqueous acetic acid and chlorine gas or sodium hypochlorite in the presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in the presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride. The sulfonyl chloride is converted to a sulphonamide and treated with phenyl(4,6-dimethoxypyrimidin-2-yl)carbamate to obtain azimsulfuron or its salts, isomers and other derivatives thereof.</p> |
