[(R)-3-oxo-4-phenylmethanesulfonylamino-morpholin-2-yl]-acetic acid methyl ester

[(R)-3-oxo-4-phenethylamino-morpholin-2-yl]-acetic acid

[(R)-3-oxo-4-phenethylamino-morpholin-2-yl]-acetic acid methyl ester

[(R)-4-benzylamino-3-oxo-morpholin-2-yl]-acetic acid methyl ester

N-(4-benzyloxycarbonylamidino-benzyl)-2-[(R)-3-oxo-4-(3-phenyl-propylamino)-morpholin-2-yl]-acetamide acid benzyl ester