Asp(OtBu)-Val-Gly-NH2

(S)-3-((S)-2-{(R)-2-[(S)-2-tert-Butoxycarbonylamino-3-(4-hydroxy-phenyl)-propionylamino]-propionylamino}-3-phenyl-propionylamino)-N-{(S)-1-[(S)-1-(carbamoylmethyl-carbamoyl)-2-methyl-propylcarbamoyl]-2-methyl-propyl}-succinamic acid benzyl ester

Z-Val-Val-Gly-NH2

Val-Asp(OtBu)-Val-Gly-NH2

H-Asp(OBzl)-Val-Val-Gly-NH2