Synthesis of the antihypertensive drug telmisartan

Objective: To synthesize telmisartan,and then optimize its process.Methods: Using 3-methyl-4-aminobenzonic acid as the starting material,2-n-propyl-4-methyl-6-carboxy benzimidazole was synthesized via esterification,acylation,nitration,reduction,cyclization and hydrolysis.This compound was condensed with N-methyl-o-phenylenediamine in polyphosphoric acid,and the product then reacted with 2-cyano-4'-bromomethylbiphenyl to produce telmisartan after hydrolysis.Results and Conclusion: The target compound is obtained under mild reaction condition with lower cost,which is suitable for large-scale production.