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Selective C−H Halogenation with a Highly Fluorinated Manganese Porphyrin
Author(s) -
Li Gang,
Dilger Andrew K.,
Cheng Peter T.,
Ewing William R.,
Groves John T.
Publication year - 2018
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.201710676
Subject(s) - halogenation , chemistry , porphyrin , manganese , steric effects , stereoselectivity , catalysis , halogen , ligand (biochemistry) , molecule , photochemistry , substrate (aquarium) , medicinal chemistry , combinatorial chemistry , organic chemistry , alkyl , biochemistry , receptor , oceanography , geology
Abstract The selective C−H functionalization of aliphatic molecules remains a challenge in organic synthesis. While radical chain halogenation reactions provide efficient access to many halogenated molecules, the use of typical protocols for the selective halogenation of electron‐deficient and strained aliphatic molecules is rare. Herein, we report selective C−H chlorination and fluorination reactions promoted by an electron‐deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for the aliphatic halogenation of recalcitrant, electron‐deficient, and strained substrates with unique regio‐ and stereoselectivity. UV/Vis analysis during the course of the reaction indicated that an oxo‐Mn V species is responsible for hydrogen‐atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step.