A mild system for room-temperature C-H arylation using aryl diazonium salts has been developed.  This was made possible by the merger of palladium catalyzed C-H functionalization and visible-light photocatalysis.  We propose that these reactions proceed via aryl radical intermediates, which are generated by visible light and a ruthenium photocatalyst.  This kinetically reactive aryl radical oxidant enables the use of lower reaction temperatures than were possible for previous C-H arylation reactions.  This system was successively applied to substrates containing a variety of directing groups and functional groups, and was effective with diverse aryl diazonium salts.  This first example of a merger of palladium catalyzed C-H functionalization and visible-light photocatalysis opens the door to new possibilities of reactivity.

Room-temperature C−H arylation by visible-light photocatalysis and Pd-catalyzed C−H functionalization

244th National Meeting (2012)

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