Increasing the Purity of Lafutidine Using a “Suicide Substrate”

When preparing lafutidine, we found that the main impurity was dihydrolafutidine. On the basis of the chemical structure of dihydrolafutidine and the mechanism of its production, we decided to use a “suicide substrate” in the drug preparation to increase the purity of lafutidine. By calculating the energy barrier of the reduction reaction with a quantum-chemical method and evaluating the appropriate physicochemical properties of the terminal olefins, we chose 1-hexene as the suicide substrate to effectively control the formation of dihydrolafutidine in the synthesis of lafutidine. The experimental results showed that the content of the impurity, dihydrolafutidine, decreased from 1.5% to less than 0.05%, proving that using a suicide substrate is an effective method to reduce the formation of the relevant byproduct in drug production. In addition, this method is operationally simple and is suitable for industrial applications.