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Facile Synthesis of Benzimidazoles via N-Arylamidoxime Cyclization
Hongjian Qin1,2, Abdullajon Odilov3,2, Emmanuel Mintah Bonku3,2
1Key Laboratory of Plant Resources and Chemistry in Arid Regions, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, South Beijing Road 40-1, Urumqi, Xinjiang 830011, P.R. China.
Abstract:
A facile synthesis of benzimidazoles was described by a one-pot process containing acylation-cyclization of N-arylamidoxime. This method provided an alternative synthesis of benzimidazoles with a certain diversity of substituted groups in acceptable yields (up to 96%). More importantly, the construction of bis-benzimidazole (8), the key intermediate for making telmisartan, was achieved by adopting this method that enabled avoiding the undesired nitration with nitric/sulfuric acid and the cyclization in polyphosphoric acid in the existing operations.
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