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Synthesis of Axially Chiral Styrenes through Pd‐Catalyzed Asymmetric C−H Olefination Enabled by an Amino Amide Transient Directing Group
Author(s) -
Song Hong,
Li Ya,
Yao QiJun,
Jin Liang,
Liu Lei,
Liu YanHua,
Shi BingFeng
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201915949
Subject(s) - chemistry , thioamide , amide , enantioselective synthesis , axial symmetry , catalysis , axial chirality , yield (engineering) , chiral auxiliary , combinatorial chemistry , stereochemistry , organic chemistry , materials science , structural engineering , engineering , metallurgy
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.