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Next‐Generation D 2 ‐Symmetric Chiral Porphyrins for Cobalt(II)‐Based Metalloradical Catalysis: Catalyst Engineering by Distal Bridging
Author(s) -
Hu Yang,
Lang Kai,
Tao Jingran,
Marshall McKenzie K.,
Cheng Qigan,
Cui Xin,
Wojtas Lukasz,
Zhang X. Peter
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201812379
Subject(s) - cyclopropanation , catalysis , porphyrin , cobalt , alkyl , amide , stereoselectivity , chemistry , ligand (biochemistry) , bridging ligand , metal , polymer chemistry , materials science , stereochemistry , photochemistry , organic chemistry , biochemistry , receptor
Novel D 2 ‐symmetric chiral amidoporphyrins with alkyl bridges across two chiral amide units on both sides of the porphyrin plane (designated “HuPhyrin”) have been effectively constructed in a modular fashion to permit variation of the bridge length. The Co II complexes of HuPhyrin, [Co(HuPhyrin)], represent new‐generation metalloradical catalysts where the metal‐centered d‐radical is situated inside a cavity‐like ligand with a more rigid chiral environment and enhanced hydrogen‐bonding capability. As demonstrated with cyclopropanation and aziridination as model reactions, the bridged [Co(HuPhyrin)] functions notably different from the open catalysts, exhibiting significant enhancement in both reactivity and stereoselectivity. Furthermore, the length of the distal alkyl bridge can have a remarkable influence on the catalytic properties.