Facile Synthesis of 1-Adamantyl Esters of L-α-Amino Acids, a New Class of Carboxy Protected Derivatives
作者:Stella M. Iossifidou、Cleanthis C. Froussios
DOI:10.1055/s-1996-4396
日期:1996.11
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.