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. 2012 Dec 14;354(18):3517-3522.
doi: 10.1002/adsc.201200738.

Combining Transition Metal Catalysis with Radical Chemistry: Dramatic Acceleration of Palladium-Catalyzed C-H Arylation with Diaryliodonium Salts

Sharon R Neufeldt  1 , Melanie S Sanford
Affiliations

Combining Transition Metal Catalysis with Radical Chemistry: Dramatic Acceleration of Palladium-Catalyzed C-H Arylation with Diaryliodonium Salts

Sharon R Neufeldt et al. Adv Synth Catal. .

Abstract

This paper describes a photoredox palladium/iridium-catalyzed C-H 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 ºC 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-thermal reaction with diaryliodonium reagents that is believed to proceed via an 'ionic' 2e- pathway and requires a much higher reaction temperature (100 ºC).

Keywords: C–H activation; diaryliodonium salts; palladium; photochemistry; radicals.

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Figures

Scheme 1
Scheme 1
Two different pathways for Pd-catalyzed C–H arylation with Ph2I+.
Scheme 2
Scheme 2
Possible mechanism for the Pd/Ir-catalyzed C– H arylation with Ar2I+.
See this image and copyright information in PMC

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