Preparation of 2-Amino-4,6-dimethoxypyrimidine 2-Hydroxy-4,6-dihydroxypyrimidine was obtained by refluxing guanidine nitrate with diethyl malonate in ethanol and sodium ethoxide at reflux for 4 hours. 97%; then 2-amino-4,6-dihydroxypyrimidine chlorinated by POCl3, refluxing reaction 1.5h, reached the end of the steamed out of the remaining POCl3, ammonia was added to adjust the pH to 7~8, to neutralize the reaction The metaphosphoric acid and hydrogen chloride were washed with ammonium brine, filtered and dried to give 2-amino-4,6-dichloropyrimidine in 80% yield. The above product was reacted with sodium methoxide, refluxed for 6 hours, cooled and filtered, distilled out. Methanol, plus appropriate amount of water, precipitation of a solid, filtered and dried to give 2-amino-4,6-dimethoxypyrimidine, yield 91%.
2-Amino-4,6-dimethoxypyrimidine can also be prepared by the following synthetic route: using urea and diethyl malonate in the presence of sodium ethoxide, the reaction produces 2,4,6-trihydroxypyrimidine. It is chlorinated with phosphorus trichloride, aminated in the presence of sodium amide, and finally reacted with sodium methoxide to obtain it. Or use malononitrile to react with methanol and hydrogen chloride to produce 1,3-dimethoxy carbodiimide bis-hydrochloride salt, then control the reaction with quantitative sodium methoxide and tend to rearrange to produce mono-hydrochloride salt, then react with cyanamide , Cyclized rearrangement system. Preparation of Methyl Orthoformate Benzene Sulfonyl Isocyanate Preparation of methyl benzyl phthalate is first performed. O-methylbenzoic acid is chlorinated with phosphorous trichloride (or phosgene) to produce o-methylbenzoyl chloride. Chlorohydrin is used to chlorinate o-chloromethyl benzoyl chloride in the presence of initiator BPO. Methanol esterification obtained. Aqueous methyl benzyl sulfonate is then prepared. Methyl orthomethyl formate benzyl chloride and thiourea were refluxed in ethanol for 1 hour to generate methyl benzyl hydrazine hydrazine hydrochloride, and then chlorine chlorination was performed at 0 to 5 °C for 1 hour to obtain methyl benzyl sulfonyl chloride. In the presence of an organic solvent, the reaction temperature is less than 20°C to aminate ammonia to give methyl ortho methyl formate benzyl sulfonamide. Finally methyl benzyl sulfonyl isocyanate was prepared. Methyl orthoformate benzyl sulfonamide in the presence of n-butylisocyanate, organic base (1,4-diazabicyclo-2,2,2-octane, or DABCO) in the presence of xylene As a solvent, phosgene was introduced at 120° C. for 3 h, and xylene and n-butyl isocyanate were distilled off to obtain methyl benzyl sulfonyl isocyanate. Synthesis of Bensulfuron-methyl using the Xylene Solution of Methyl Orthoformate Benzenesulfonyl Isocyanate and 2-Amino-4,6-dimethoxypyrimidine at room temperature for 8~10h, distilling off xylene with chlorine Butane was washed and dried to produce bensulfuron methyl.