?-Peptides Forming More Stable Secondary Structures than ?-Peptides: Synthesis and helical NMR-solution structure of the ?-hexapeptide analog of H-(Val-Ala-Leu)2-OH
作者:Tobias Hintermann、Karl Gademann、Bernhard Jaun、Dieter Seebach
DOI:10.1002/hlca.19980810514
日期:——
acid, and (R)-4-amino-6-methylheptanoic acid. The precursors were prepared either by double Arndt-Eistert homologation of the protected amino acids Boc-Val-OH, Boc-Ala-OH, and Boc-Leu-OH (Schemes 1 and 2), or by the superior route involving olefination/hydrogenation of the corresponding aldehydes (Boc-valinal, Boc-alaninal, and Boc-leucinal; Scheme 3). Conventional peptide-coupling methodology (EDC/HOBt)
为了与相应的α-和β-六肽H-(Val-Ala-Leu)2 -OH(A)和H-(β-HVal-β-HAla-β-HLeu)2 -OH(B)进行比较,我们现在准备了由手性相似的(S)-4-氨基丁酸,(R)-4-氨基-5-甲基己酸和(R)-4-氨基-6-甲基庚酸构建的相应的γ-六肽1。通过对受保护氨基酸Boc-Val-OH,Boc-Ala-OH和Boc-Leu-OH进行双重Arndt - Eistert同源性制备前体(方案1和2),或通过涉及相应醛的烯化/加氢的高级途径(Boc-戊醛,Boc-丙氨酸和Boc-亮氨酸;方案3)。常规肽偶合方法(EDC / HOBT)提供的γ-六肽1(通过中间γ-二-和γ-三肽衍生物9 - 11)。在(D 5)吡啶和CD 3 OH溶液(COSY,TOCSY,HSQC,HMBC,ROESY)中进行的NMR测量分析表明,γ-六肽1采用右旋螺旋结构((P)-2.6 1