Facile and green synthesis of 4,6-dimethoxy-2-methylsulfonylpyrimidine using chloromethane as methylating agent

摘要

4,6-dimethoxy-2-methylsulfonylpyrimidine (DMSP) is an important chemical intermediate which has been widely used in the synthesis of plant growth regulators, pesticides, and fungicides. However, the traditional synthetic manufacturing process involves highly toxic dimethylsulfate and highly corrosive phosphorus oxychloride, causing serious environmental problems. To overcome these problems, we utilized chloromethane instead of dimethylsulfate as a methylating agent to synthesize DMSP. The reaction was shortened to only2 steps. Since 4,6-dimethoxy-2-methylthiopyrimidine is the key intermediate in the synthesis of DMSP, it is of great importance to improve the conversion and selectivity. In this work, 4,6-dimethoxy-2-methylthiopyrimidine was synthesized from 2-thiobarbituric acid in the presence of potassium carbonate and chloromethane through a one-step procedure. By optimization of reaction conditions, high conversion of 2-thiobarbituric acid (85.7%) and selectivity of 4,6-dimethoxy-2-methyl thiopyrimidine (53.1%) were obtained. Compared to the traditional synthetic pathway, our new synthetic process is more economical and environment-friendly.