Scalable Synthesis of TRPV1 Antagonist Bipyridinyl Benzimidazole Derivative via the Suzuki–Miyaura Reaction and Selective SeO(2) Oxidation

In this study, a kilogram-scale synthesis of a potent TRPV1 antagonist, 1, is described. To synthesize bipyridinyl benzimidazole derivative 1, we have developed a scalable Suzuki–Miyaura reaction capable of providing a key intermediate, 6′-methyl-3-(trifluoromethyl)-2,3′-bipyridine 4, on a kilogram scale. Then, unlike the existing oxidation reaction pathway, two synthetic routes that can be applied to mass production of bipyridinyl carboxylic acid intermediate 5 or aldehyde intermediate 6 were developed by appropriately controlling the oxidation reaction using a selenium dioxide oxidizing agent. Using our developed synthetic procedure, which includes Suzuki–Miyaura coupling, selective selenium dioxide oxidation, and benzimidazole formation, multi-kilogram-scale bi-pyridinyl benzimidazole derivative 1 can be synthesized.