Both S-condensation and N-condensation reaction could take place when derivatives of 2-dimethylaminobenzylchloride react with substituted 2-mercapto-benzimidazole, mainly depending on the substituted groups of 2-dimethylaminobenzyl-chloride. It is important to control the reaction toward the desired S-condensation in order to produce the key intermediate of a novel type of proton pump inhibitor. The rules and controlling methods of the reaction were proposed. The key intermediates which are difficult to prepare by the literature method may be synthesized by using the improved method 3, that is derivatives of 2-dimethylaminobenzylchloride react with sodium salt of substituted 2-mercaptobenzimidazole.

Key words: RULES, MERCAPTO COMPOUNDS, QUANTUM CHEMISTRY, NUCLEOPHILIC REACTION, CALCULATION, ORGANO CHLORIDE COMPOUNDS, SUBSTITUTION REACTION, DIMETHYLAMINO, BEN ZYL GROUP P, BENZIMIDAZOLE P