1-Adamantyl esters of several N-unprotected L-α-amino acids were directly prepared in good optical purity and yield by reaction of the corresponding amino acid 4-toluenesulfonate salts with 1-adamantanol (AdOH) and dimethyl sulfite in boiling toluene. The fully protected tripeptide Boc-Leu-Ala-Val-OAd, prepared from TsOH.H-Val-OAd (entry 2b) was amino deprotected to H-Leu-Ala-Val-OAd by the action of 4N HCl in dioxane for 25 minutes at 20°C, while the latter was carboxy deprotected to the free peptide by the action of trifluoroacetic acid for 60 minutes at 20°C. The 1-adamantyl ether of threonine (5) was also prepared and the 1-adamantyl moiety was completely cleaved from Troc-Thr(OAd)-OH by the action of trifluoroacetic acid for 30 minutes at 20°C.
在沸腾的
甲苯中,通过相应的
氨基酸 4-甲
苯磺酸盐与
1-金刚烷醇(AdOH)和
亚硫酸二甲酯反应,直接制备了几种 N-未保护的 L-δ-
氨基酸的 1-
金刚烷基酯,具有良好的光学纯度和收率。由 TsOH.H-Val-OAd 制备的完全保护的三肽 Boc-Leu-Ala-Val-OAd(条目 2b)在 20°C 下于
二噁烷中用 4N HCl 作用 25 分钟
氨基脱保护为 H-Leu-Ala-Val-OAd,而后者在 20°C 下用
三氟乙酸作用 60 分钟羧基脱保护为游离肽。还制备了苏
氨酸的 1-
金刚烷基醚 (5),在 20°C 温度下,
三氟乙酸作用 30 分钟,1-
金刚烷基从 Troc-Thr(OAd)-OH 完全裂解。