A solution of 1-(2-aminoethyl)-N,N-diisobutyl-2-[(3,4,5-trimethoxyphenyl)amino]-1H-benzimidazole-5-carboxamide (30 mg, 1 eq) and cyclohexanecarboxaldehyde (5 mg, 0.8 eq) in methanol (0.7 ml) is stirred at a temperature of approximately 20° C. for 4 hours. Borohydride resin (48 mg, 2.5 mmol/g, Amberlite®, IRA-400) is added and the mixture is stirred for 18 hours then dichloromethane (0.5 ml) and benzyloxybenzaldehyde Wang resin (37 mg, 3.22 mmol/g, Novabiochem) are added. After stirring overnight, the mixture is filtered and the filtrate is evaporated under reduced pressure in order to produce the expected compound in the form of a beige foam (18 mg, 65%).
