Complete 2,5-Diastereocontrol in the Organocatalytic Enantioselective [3+2] Cycloaddition of Enals with Azomethine Ylides Derived from α-Iminocyanoacetates: Asymmetric Synthesis of Pyrrolidines with Four Stereocentres
作者:Silvia Reboredo、Jose L. Vicario、Dolores Badía、Luisa Carrillo、Efraím Reyes
DOI:10.1002/adsc.201100432
日期:2011.12
ylide precursors in the catalytic enantioselective [3+2] cycloaddition with α,β-unsaturated aldehydes catalyzed by (S)-α,α-diphenylprolinol leading to the fully stereocontrolled formation of pyrrolidine cycloadducts with four stereocentres, one of them being a quaternary one. The reaction proceeded with excellent yields, endo-selectivities and enantioselectivities. Remarkably, complete 2,5-diastereoselection
外消旋α-亚氨基氰基乙酸酯已被用作(A)-α,α-二苯丙醇催化的α,β-不饱和醛的对映体选择性[3 + 2]环加成反应中的甲亚胺基前体,导致完全立体控制形成吡咯烷环加合物,其中有四个立体中心,其中之一是四元中心。反应以优异的产率,内选择性和对映选择性进行。值得注意的是,在最优化的反应条件下,也已经实现了完全的2,5-非对映异构,这是通过参与分子内氢键相互作用来解释的,这有助于稳定原位生成的偶氮甲碱叶立德的一种确定的几何构型。