Metal-Free Synthesis of Unsymmetrical Ureas and Carbamates from CO2 and Amines via Isocyanate Intermediates
Yiming Ren and Sophie A. L. Rousseaux*
*Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada, Email: srousseachem.utoronto.ca
Y. Ren, S. A. L. Rousseaux, J. Org. Chem., 2018, 83, 913-920.
DOI: 10.1021/acs.joc.7b02905 (free Supporting Information)
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In a mild and metal-free synthesis of aryl isocyanates from arylamines, a carbamic acid intermediate, derived from the arylamine starting material and CO2 in the presence of DBU, is dehydrated by activated sulfonium reagents to generate the corresponding isocyanate. The latter can be trapped by various amines and alcohols to make unsymmetrical ureas and carbamates, respectively.
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