Organic Chemistry, Facultat de Química, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Catalonia, Spain.
Org Lett. 2021 Feb 5;23(3):651-655. doi: 10.1021/acs.orglett.0c03609. Epub 2021 Jan 11.
Chiral nitroalkenes are used for the first time in Michael additions of aldehydes, catalyzed by pyrrolidine derivatives. They yield the same major stereoisomer with either ()-proline or ()-proline, but this asymmetric induction does not overcome the effect of sterically more congested catalysts. Nitrocyclobutane intermediates are often formed, which are more stable than those from ()-1-nitro-2-phenylethene. The cyclobutanes and final products were characterized by 2D NMR and chemical correlations.
手性硝基烯烃首次被用于醛的迈克尔加成反应，由吡咯烷衍生物催化。反应中，用（）-脯氨酸或（）-脯氨酸作为催化剂，均得到相同的主要立体异构体，但这种不对称诱导并不能克服空间位阻更大的催化剂的影响。通常会形成硝基环丁烷中间体，它们比（）-1-硝基-2-苯乙烯的中间体更稳定。通过二维 NMR 和化学相关确定了环丁烷和最终产物的结构。
