Asymmetric nitrone cycloadditions and their application to the synthesis of enantiopure pyrrolidine and pyrrolizidine derivatives
作者:Nikolaos G. Argyropoulos、Theodoros Panagiotidis、Evdoxia Coutouli-Argyropoulou、Catherine Raptopoulou
DOI:10.1016/j.tet.2006.10.076
日期:2007.1
The cycloaddition reactions of a pair of chiral pyrroline-N-oxides derived from d-ribose with some typical mono and disubstituted alkenes are reported. In all these reactions with monosubstituted alkenes as well as with dimethyl maleate the preferred stereochemical outcome of the cycloaddition step comes from a 5-exo-anti transition state whereas stereoisomers from the 5-exo-syn transition state are
报道了衍生自d-核糖的一对手性吡咯啉-N-氧化物与一些典型的单和双取代的烯烃的环加成反应。在所有这些与单取代的烯烃以及与马来酸二甲酯的反应中,环加成步骤的优选立体化学结果来自5-外-反过渡态,而来自5-外-顺式转变态的立体异构体也作为次要加合物存在。与富马酸二甲酯的主要加合物是来自一个反应4 -外型- 5 -内型-顺式过渡状态。所获得的异恶唑烷在还原性开环条件下的进一步行为取决于预先存在的取代基的种类和几何形状,并且它们被转化为对映体纯的吡咯烷或吡咯烷酮衍生物。