Rigid Dipeptide Mimics: Synthesis of Enantiopure C6-Functionalized Pyrrolizidinone Amino Acids
作者:Mallem H. V. Ramana Rao、Eulàlia Pinyol、William D. Lubell
DOI:10.1021/jo0616761
日期:2007.2.1
in a turn conformation. 6-Hydroxy pyrrolizidinone amino carboxylate 1 may thus find application as a constrained alaninylhydroxyproline dipeptide mimic. In addition, alkylation of the hydroxyl group provided orthogonally protected pyrrolizidinone amino dicarboxylate (6R)-25, demonstrating potential for expanding the diversity of these rigid dipeptide surrogates for the exploration of peptide conformation−activity
对映体(3 S,5 S,6 R,8 S)-和(3 S,5 S,6 S,8 S)-6-羟基吡咯烷二酮3- N-(Boc)氨基8-甲基羧酸盐(6 R)-从(2 S)-α-叔丁基N-(PhF)天门冬氨酸β-醛(10)开始,通过七个步骤合成了(6 S)-1和(6 S)-1。羰基催化的β-醛10酰化缩醛,然后进行乙酰化,得到了非对映异构体的可分离混合物(2 S,5 RS,7 S)-二氨基-4-氧代-5-乙酰氧基辛二酸酯(13)。各个α-乙酰氧基酮13的还原胺化和内酰胺环化提供了羟基吡咯烷二酮(6 R)-和(6 S)-1并保留了C6-位立体化学。(6 R)-1的X射线晶体学研究表明,杂环中约束的二面角与II'型β拐角的i +1和i + 2残基的理想值一致。上氢键研究Ñ “甲基Ñ(BOC)aminopyrrolizidin -2-酮甲酰胺(6 - [R)和(6 S)-21在DMSO- d 6中显示出不同