Lithium hydroxide (141 mg, 5 eq) is added to methyl 4-[(6-{[bis(3-methylbutyl)amino]carbonyl}-1-{3-[(tert-butoxycarbonyl)amino]propyl}-1H-benzimidazol-2-yl)amino]benzoate prepared according to reaction diagram A, Example A1, (405 mg, 1 eq) in a mixture of tetrahydrofuran (4 ml) and water (3 ml). The mixture is heated under reflux for 18 hours then cooled down to ambient temperature and concentrated under reduced pressure at 40° C. Dichloromethane (50 ml) and water (20′ ml) are added to the residue. The mixture is acidified by the addition of acetic acid to pH 5. After decantation and extractions, the combined organic phases are dried over sodium sulphate and concentrated under reduced pressure. The solid obtained is taken up in ethyl ether in order to produce the expected compound (309 mg; 79%).
