Solid-phase synthesis of bis-2-imidazolidinethiones from resin-bound tripeptides

[GRAPHICS] The exhaustive reduction of resin-bound tripeptides with borane afforded th ree secondary amines and one primary amine. The treatment of the solid-supp ort polyamines with thiocarbonyldiimidazole afforded, following cleavage of the solid support, the corresponding his-cyclic thiourea in good purity an d yield.