Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.
Angew Chem Int Ed Engl. 2020 Apr 16;59(16):6576-6580. doi: 10.1002/anie.201915949. Epub 2020 Feb 25.
The atroposelective synthesis of axially chiral styrenes remains a formidable challenge due to their relatively lower rotational barriers compared to the biaryl atropoisomers. Herein, we describe the construction of axially chiral styrenes through Pd -catalyzed atroposelective C-H olefination, using a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with good yields and high enantioselectivity (up to 95 % yield and 99 % ee). Carboxylic acid derivatives of the resulting axially chiral styrenes showed superior enantiocontrol over the biaryl counterparts in Co -catalyzed enantioselective C(sp )-H amidation of thioamide. Mechanistic studies suggest that C-H cleavage is the enantioselectivity-determining step.
轴手性苯乙烯的对映选择性合成仍然是一个巨大的挑战，因为与联芳基对映异构体相比，它们的旋转势垒相对较低。在此，我们描述了通过 Pd 催化的轴手性 C-H 烯烃化反应，使用庞大的氨基酰胺作为瞬态手性辅助试剂，来构建轴手性苯乙烯。各种轴手性苯乙烯以良好的收率和高对映选择性（高达 95%的产率和 99%的 ee）得到。所得轴手性苯乙烯的羧酸衍生物在 Co 催化的硫酰胺对映选择性 C(sp3)-H 酰胺化反应中对映体控制优于联芳基类似物。机理研究表明 C-H 断裂是对映选择性决定步骤。
