Synthesis of Axially Chiral Styrenes through Pd‐Catalyzed Asymmetric C−H Olefination Enabled by an Amino Amide Transient Directing Group. Issue 16 (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 international edition. Volume 59:Issue 16(2020)
• Page Start: 6576
• Page End: 6580
• Publication Date: 2020-02-25
• Subjects: atroposelectivity -- axially chiral styrenes -- C−H olefination -- palladium -- transient directing groups; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201915949
• Languages: English
• ISSNs: 1433-7851

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 : Axially chiral styrenes were constructed through a Pd II ‐catalyzed atroposelective C−H olefination with a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with good yields and high enantioselectivity. Carboxylic acid derivatives of these axially chiral styrenes showed superior enantiocontrol compared to the biaryl counterparts in Co III ‐catalyzed enantioselective C(sp 3 )−H amidation of ferrocenes.