A mixture of methyl 1-[(2S,3R)-2-benzyloxy-5-(1-naphthyl)- 3-pentyl]imidazole-4-carboxylate (obtained in Example 3(20))(97 mg) and sodium hydroxide (12 mg) in ethanol (2 ml) and water (0.2 ml) was stirred at room temperature overnight. The solvent was evaporated and the residue was taken up in a mixture of ethyl acetate and water. The aqueous layer was separated, acidified to pH 3 with hydrochloric acid, and extracted with ethyl acetate. The extract was dried and evaporated to give a pale brown powder of 1-[(2S,3R)-2-benzyloxy-5-(1-naphthyl)-3-pentyl]imidazole-4-carboxylic acid (84.5 mg).
