Synthesis and Conformational Analysis of Cyclic Homooligomers from Pyranoid ε-Sugar Amino Acids
作者:Andrés Feher-Voelger、Jorge Borges-González、Romen Carrillo、Ezequiel Q. Morales、Javier González-Platas、Tomás Martín
DOI:10.1002/chem.201303841
日期:2014.4.1
New pyranoid ε‐sugar amino acids were designed as building blocks, in which the carboxylic acid and the amine groups were placed in positions C2 and C3 with respect to the tetrahydropyran oxygen atom. By using standard solution‐phase coupling procedures, cyclic homooligomers containing pyranoid ε‐sugar amino acids were synthesized. Conformation analysis was performed by using NMR spectroscopic experiments
设计了新的吡喃类ε-糖氨基酸作为构建基,其中羧酸和胺基相对于四氢吡喃氧原子位于C2和C3位置。通过使用标准的溶液-相偶联方法,合成了含有吡喃类ε-糖氨基酸的环状均聚物。使用NMR光谱实验,FTIR光谱研究,X射线分析和理论构象搜索进行构象分析。这些研究表明在吡喃环的C4位上存在甲氧基基团会在环二肽中产生重要的结构变化。当存在甲氧基时,该结构通过吡喃环的氧原子与酰胺质子之间的残基氢键而崩溃。然而,当环二肽缺少甲氧基时,采用U型结构,其中有一个亲水性凹面,带有四个氧原子和两个指向腔中心的酰胺质子。此外,我们发现了重要的证据,证明弱静电相互作用(如五元氢键合假环(C5)在酰胺质子和醚氧原子之间,在大环的构象平衡中和在环状四肽的环化步骤中。