Article

Contemporaneous dual catalysis: chemoselective cross-coupling of catalytic vanadium-allenoate and π-allylpalladium intermediates.

Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States.
Journal of the American Chemical Society (Impact Factor: 10.68). 06/2011; 133(32):12824-33. DOI: 10.1021/ja204817y
Source: PubMed

ABSTRACT This paper presents a detailed investigation of a dual catalytic system that combines a vanadium-catalyzed Meyer-Schuster rearrangement and a palladium-catalyzed allylic alkylation. The implementation of this novel reaction relies on matching the formation rates of vanadium-allenoate and π-allylpalladium intermediates with their bimolecular coupling rate in order to minimize the undesired protonation or O-alkylation of the catalytically generated intermediates. Chemoselectivity in this dual catalytic process was successfully achieved by adjusting ligand structure and catalyst loading ratios of the vanadium and palladium catalysts. A great range of coupling partners for both the propargyl alcohol and allyl carbonate components are readily accommodated in this new transformation, which in turn provides a novel avenue to a variety of α-allylated α,β-unsaturated ketones, esters, and amides in moderate to excellent isolated yields.

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