Synthesis of telmisartan via oxidative cyclization

An efficient synthesis has been developed for telmisartan. The key strategy is the construction of substituted bis-benzimidazole 11b by oxidative cyclization of substituted amidine 15 with bis(trifluoroacetoxy)iodobenzene. In this research, we provided telmisartan from the starting compound 12 in an overall yield of 61.5% by four steps while avoiding many issues previously reported.