1-(1-benzyloxycarbonylethyl)-3-methylene-azetidin-2-one

H-Asp(O-tBu)-Ser-Ser

2S-Methyl-3-p-toluenesulfonyl-3-azapentandioic acid

methyl N-tosyl-N-(methoxycarbonylmethyl)alaninate

H-Ser-Ala-Ala-OBzl