Web Release Date: December 9,
Palladium-Catalyzed Benzene Arylation: Incorporation of Catalytic Pivalic Acid as a Proton Shuttle and a Key Element in Catalyst Design
Center for Catalysis Research and Innovation, University of Ottawa, Department of Chemistry, 10 Marie Curie, Ottawa, Ontario, Canada K1N 6N5
Received October 5, 2006
Abstract:
A palladium-pivalic acid cocatalyst system has been developed that exhibits unprecedented reactivity in direct arylation. This reactivity is illustrated with the first examples of high yielding direct metalation-arylation reactions of a completely unactivated arene, benzene. Experimental and computational evidence indicates that the pivalate anion is a key component in the palladation/C-H bond breaking event, that it lowers the energy of C-H bond cleavage and acts as a catalytic proton shuttle from benzene to the stoichiometric carbonate base. Eight examples of substituted aryl bromides are included which undergo direct arylation with benzene in 55-85% yield.
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