Guanidilation of substituted aniline (I) with protected guanidine (II) provides derivative (III), whose Boc group is removed by treatment with TFA or HCl to afford (4-aminomethyl)phenyl-2,3-di(benzyloxycarbonyl)guanidine (IV). Finally, the target product is obtained by coupling of (IV) with 1-adamantyl-isocyanate (V), followed by removal of the protecting group by hydrogenation over Pd/C.