The reaction of m-xylene-alpha,alpha'-diamine (I) with N,N'-bis(tert-butoxycarbonyl)pyrazole-1-carboxamidine (II) in THF gives the protected guanidine (III), which is acylated at the free amino group with 2,3-diphenylpropionyl chloride (IV) and triethylamine in dichloromethane affording the amide (V). The condensation of (V) with tetrahydrofuran-2-ylmethylamine (VI) in refluxing THF affords the protected amidinourea (VII), which is finally treated with TFA in dichloromethane.