Exercises in Pyrrolidine Chemistry: Gram Scale Synthesis of a Pro-Pro Dipeptide Mimetic with a Polyproline Type II Helix Conformation
作者:Cédric Reuter、Peter Huy、Jörg-Martin Neudörfl、Ronald Kühne、Hans-Günther Schmalz
DOI:10.1002/chem.201101704
日期:2011.10.17
A practical and scalable synthesis of a Fmoc‐protected tricyclic dipeptide mimetic (6), that is, a 1,4‐diaza‐tricyclo‐[8.3.03, 7]‐tridec‐8‐ene derivative resembling a rigidified di‐L‐proline in a polyproline type II (PPII) helix conformation, was developed. The strategy is based on a Ru‐catalyzed ring‐closing metathesis of a dipeptide (4) prepared by PyBOP coupling of cis‐5‐vinylproline tert‐butylester
一个Fmoc-保护的二肽三环模拟物(的实际和可扩展的合成6),即,1,4-二氮杂-三环[8.3.0 3,7 ] -tridec -8-烯衍生物类似于僵化二大号开发了聚脯氨酸II型(PPII)螺旋构象的脯氨酸。该策略基于Ru催化的二肽(4)的闭环复分解反应,该复分解反应是通过PyBOP偶联顺式-5-乙烯基脯氨酸叔丁酯(2)和反式-N -Boc-3-乙烯基脯氨酸(rac - 3)制备的然后进行色谱非对映体分离。构件2是从L准备的脯氨酸通过电化学C5-甲氧基化,氰化和腈转化为乙烯基取代基的六个步骤。在关键步骤中,利用Cu催化的乙烯基MgBr的1,4-加成至2,3-脱氢脯氨酸衍生物的五个步骤制备了结构单元rac - 3。在研究过程中,观察到保护基对2,3-和2,5-二取代的吡咯烷衍生物的反应性有微弱的依赖性。几种中间体的构型和构象偏好是通过X射线晶体学确定的。发达的合成方法可以制备大量的6,将用于