Synthesis of Axially Chiral Styrenes through Pd‐Catalyzed Asymmetric C−H Olefination Enabled by an Amino Amide Transient Directing Group. (25th February 2020)

• Record Type: Journal Article
• Authors: Song, Hong; Li, Ya; Yao, Qi‐Jun; Jin, Liang; Liu, Lei; Liu, Yan‐Hua; Shi, Bing‐Feng
• Is Part Of: Angewandte Chemie. Volume 132:Number 16(2020)
• Page Start: 6638
• Page End: 6642
• Publication Date: 2020-02-25
• Subjects: Atroposelektivität -- Axial chirale Styrole -- C-H-Olefinierung -- Palladium -- Transiente dirigierende Gruppen; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201915949
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: 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 II ‐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 III ‐catalyzed enantioselective C(sp 3 )−H amidation of thioamide. Mechanistic studies suggest that C−H cleavage is the enantioselectivity‐determining step. Abstract : Axial chirale Styrole wurden durch eine Pd II ‐katalysierte atropselektive C‐H‐Olefinierung mit einem sperrigen Aminoamid als chiralem Auxiliar mit hoher Enantioselektivität hergestellt. Die Carbonsäurederivate dieser axial chiralen Styrole zeigen in der Co III ‐katalysierten enantioselektiven C(sp 3 )‐H‐Amidierung von Ferrocenen eine bessere Enantiokontrolle als die Biaryle.