Methanol → Methyl 2-butyl-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]benzimidazole-7-carboxylate

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Reaction Steps

A mixture of 2-butyl-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]benzimidazole-7-carboxylic acid (1.8 g) in methanol (18 ml) and conc. sulfuric acid (14.4 g) was heated for 24 hours under reflux. After removal of the solvent by evaporation, the residue was suspended with water, whose pH was adjusted to 3-4 with 1N-NaOH, followed by extraction with ethyl acetate. The organic layer was washed with water and dried. The solvent was removed by evaporation and the residue was purified by column chromatography on silica gel. Recrystallization from ethanol afforded colorless prisms (1.05 g), m.p. 153°-155° C.

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