Enantiopure 4- and 5-Aminopiperidin-2-ones: Regiocontrolled Synthesis and Conformational Characterization as Bioactive β-Turn Mimetics
作者:Klaus Weber、Ursula Ohnmacht、Peter Gmeiner
DOI:10.1021/jo000555c
日期:2000.11.1
gamma-amino acid equivalents. Using the 1,4-bis-electrophile 1b as a central intermediate, the 4- and 5-aminopiperidin-2-ones 4 and 8, respectively, were approached by regioselective functionalization and subsequent lactamization. Diastereoselective C-alkylation was performed after N-protection of the lactam functionality when exclusive trans configuration resulting in the formation of 5a-f was observed in
从天冬氨酸开始,我们合成了内酰胺桥的β-和γ-氨基酸等效物。使用1,4-双亲电子试剂1b作为中心中间体,通过区域选择性功能化和随后的内酰胺化分别接近4-和5-氨基哌啶-2-酮4和8。当在4-氨基系列中观察到导致5a-f形成的排他性反式构型时,内酰胺官能团的N-保护后进行非对映选择性C-烷基化。另一方面,对于5-氨基内酰胺5a,b的烷基化,典型的是顺式选择性。为了研究内酰胺结构单元通过分子内氢键诱导反转结构的能力,分别从4a和8a制备了代表II型和III型均质弗里德内酰胺的模型拟肽12和14。在室温下通过稀溶液(1 mM)的IR和NMR光谱进行的构象分析清楚地表明,4-氨基哌啶-2-酮衍生物12主要采用由CO-HN氢键稳定的11位元反转结构。环。VT NMR实验表明,当Deltadelta(NH)/ DeltaT = -6.5表示低温下分子内氢键的数量较高时,末端NH的温度依赖性很大。证明了