The Boc and Bzl protected tyrosine (Boc-Tyr(Bzl)-OH) was allowed to react with proline methyl ester hydrochloride to form the second dipeptide Boc-Tyr(Bzl)-Pro-OMe in 42% yield.

• 选择叔丁氧羰酰基(Boc)和苄基(Bzl)作为酪氨酸的氨基和侧链保护基，与脯氨酸甲酯盐酸盐缩合得二肽片段Boc-Tyr(Bzl)-Pro-OMe，产率42%25。