A general and practical method for the preparation of unsymmetrically substituted ureas has been developed utilizing palladium-catalyzed amidation. Both aryl bromides and chlorides, as well as heteroaryl chlorides, have been coupled to aryl, benzyl, and aliphatic ureas by using a novel nonproprietary bipyrazole ligand (bippyphos).
A palladium catalysis-mediated approach to coupling aliphatic alcohols with allyl carbonates has been developed. The method allows for the allylation of primary, secondary, and tertiary alcohols efficiently under mild conditions. Limitations were explored as well as the asymmetric application of the chemistry. Regiochemical and olefin geometry was controlled in the coupling of unsymmetrical allylating agents. Transient allyl carbonates were observed in the coupling, which comprised the trans-carboxylation of the allyl-carbonate with the requisite alcohol.
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