How is Azilsartan Impurity 42 (CAS: 139481-33-7) typically synthesized?

Azilsartan Impurity 42 is typically synthesized through a multi-step process involving esterification and ring closure reactions. The synthesis involves the use of common organic solvents such as dichloromethane and acetic acid. The reaction is catalyzed by a strong acid like trifluoroacetic acid (TFA) and proceeds with good selectivity and yield. The final product is purified by recrystallization and chromatography.