Solution-Phase Synthesis of a Hindered <i>N</i>-Methylated Tetrapeptide Using Bts-Protected Amino Acid Chlorides: Efficient Coupling and Methylation Steps Allow Purification by Extraction
作者:Edwin Vedejs、Chutima Kongkittingam
DOI:10.1021/jo9914115
日期:2000.4.1
N-Benzothiazole-2-sulfonyl (Bts)-protected amino acid chlorides were used to prepare the hindered cyclosporin 8-11 tetrapeptide subunit 1. The synthesis was performed via 3a and the deprotected amines 5a, 13, and 19, including three repeated cycles involving N-methylation using iodomethane/potassium carbonate, deprotection of the Bts group, and N-acylation with a N-Bts-amino acid chloride such as 9b
使用N-苯并噻唑-2-磺酰基(Bts)保护的氨基酸氯化物制备受阻的环孢菌素8-11四肽亚基1。通过3a和脱保护的胺5a,13和19进行合成,包括三个重复循环包括使用碘甲烷/碳酸钾进行N-甲基化,Bts基团的脱保护以及用N-Bts-氨基酸氯化物(如9b或9c)进行N-酰化。在比较的三种Bts裂解方法(H3PO2 / THF; NaBH4 / EtOH; PhSH / K2CO3)中,第三种给出的总收率更高。用Bts保护的N-甲基氨基酸氯化物10b对5a进行N-酰化再脱保护也非常有效,并且可以用作11的替代途径。无需色谱法即可分离出每种脱保护的胺,无需使用简单的萃取方法即可去除中性物质。副产品。