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Combining Transition Metal Catalysis with Radical Chemistry: Dramatic Acceleration of Palladium‐Catalyzed CH Arylation with Diaryliodonium Salts
Author(s) -
Neufeldt Sharon R.,
Sanford Melanie S.
Publication year - 2012
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201200738
Subject(s) - chemistry , chemoselectivity , reagent , catalysis , palladium , radical , photoredox catalysis , transition metal , combinatorial chemistry , iridium , ionic bonding , photochemistry , methanol , substrate (aquarium) , photocatalysis , organic chemistry , ion , oceanography , geology
This paper describes a photoredox palladium/iridium‐catalyzed CH arylation with diaryliodonium reagents. Details of the reaction optimization, substrate scope, and mechanism are presented along with a comparison to a related method in which aryldiazonium salts are used in place of diaryliodonium reagents. The unprecedentedly mild reaction conditions (25 °C in methanol), the requirement for light and a photocatalyst, the inhibitory effect of radical scavengers, and the observed chemoselectivity trends are all consistent with a radical‐mediated mechanism for this transformation. This stands in contrast to the analogous thermal reaction with diaryliodonium reagents that is believed to proceed via an ‘ionic’ 2 e − pathway and requires a much higher reaction temperature (100 °C).