Highly Functionalized Cyclopentane Derivatives by Tandem Michael Addition/Radical Cyclization/Oxygenation Reactions
作者:Martin Holan、Radek Pohl、Ivana Císařová、Blanka Klepetářová、Peter G. Jones、Ullrich Jahn
DOI:10.1002/chem.201500424
日期:2015.6.26
Densely functionalized cyclopentane derivatives with up to four consecutive stereocenters are assembled by a tandem Michael addition/single‐electron transfer oxidation/radical cyclization/oxygenation strategy mediated by ferrocenium hexafluorophosphate, a recyclable, less toxic single‐electron transfer oxidant. Ester enolates were coupled with α‐benzylidene and α‐alkylidene β‐dicarbonyl compounds with
由六氟磷酸铁(一种可回收的,毒性较小的单电子转移氧化剂)介导的串联迈克尔加成/单电子转移氧化/自由基环化/加氧策略组装了具有多达四个连续立体中心的密集官能化环戊烷衍生物。酯烯酸酯与α-亚苄基和α-亚烷基β-二羰基化合物偶联,具有可切换的非对映选择性。该枢转操纵元件随后控制自由基环化步骤的非对映选择性。自由基环化受体的取代模式可将环化模式从末端取代的烯烃单元的5 exo模式转换为6内酰胺模式内部取代受体的模式。氧化阴离子/自由基策略还允许通过自由基2,2,6,6-四甲基-1-哌啶氧基的氧化作用来有效终止,从而在序列中形成两个CC键和一个CO键。提出了立体化学模型,该模型考虑了所有实验结果并允许预测立体化学结果。报道了合成的环戊烷的进一步转化。