Palladium-Catalyzed N-Acylation of Monosubstituted Ureas Using Near-Stoichiometric Carbon Monoxide
Klaus Bjerglund, Anders T. Lindhardt and Troels Skrydstrup*
*Center for Insoluble Protein Structures, Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark, Email: tschem.au.dk
K. Bjerglund, A. T. Lindhardt, T. Skrydstrup, J. Org. Chem., 2012, 77, 3793-3799.
DOI: 10.1021/jo3000767 (free Supporting Information)
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A palladium-catalyzed carbonylation of urea derivatives with aryl iodides and bromides afforded N-benzoyl ureas in very good yields using near-stoichiometric amounts of carbon monoxide generated from the decarbonylation of 9-methylfluorene-9-carbonyl chloride as CO precursor. The synthetic protocol displayed good functional group tolerance. The methodology is also highly suitable for 13C isotope labeling.
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Release of carbon monoxide from COgen at temperatures higher than 50°C can be performed using both P(tBu)3 or the air stable precursor HBF4P(tBu)3 as ligand without change in results.
Anders T. Lindhardt, December 27, 2012
D. U. Nielsen, R. H. Taaning, A. T. Lindhardt, T. M. Gøgsig, T. Skrydstrup, Org. Lett., 2011, 13, 4454-4457.