[CH2:1]([CH:3]([C:6]1[C:11]2[N:12]([CH3:16])[C:13](=[O:15])[NH:14][C:10]=2C(C#N)=[CH:8][CH:7]=1)[CH2:4][CH3:5])[CH3:2].[OH-].[K+].O.[C:22]([O:28]C)([O:26][CH3:27])(OC)[CH3:23]>C1(C)C=CC=CC=1.C(O)C>[CH2:1]([CH:3]([C:6]1[C:11]2[N:12]([CH3:16])[C:13](=[O:15])[NH:14][C:10]=2[C:23]([C:22]([O:26][CH3:27])=[O:28])=[CH:8][CH:7]=1)[CH2:4][CH3:5])[CH3:2]
A mixture of 7-(1-ethylpropyl)-1-methyl-2-oxo-2,3-dihydro-1H-benzimidazole-4-carbonitrile (1.50 g, 6.17 mmol), potassium hydroxide (20.0 g, 356 mmol), water (30 ml) and ethanol (30 ml) was heated under reflux for 48 h. The reaction mixture was concentrated in vacuo. The residue was diluted with ethyl acetate and 2N hydrochloric acid was added and extracted. The extracts were washed with water, dried over magnesium sulfate and concentrated in vacuo to give crude carboxylic acid. Trimethyl orthoacetate (10 ml) and toluene (10 ml) were added to the residue and heated at 100° C. for 6 h. The reaction mixture was concentrated in vacuo. The residue was purified by column chromatography on silica gel with a 35% ethyl acetate/n-hexane to give 1.31 g (4.74 mmol, 77%) of the title compound as a white powder.
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