One-Pot, Solvent-Free Access to Unsymmetrical Ureas by Palladium-Catalysed Reductive Alkylation Using Molecular Hydrogen

Palladium-catalysed reductive alkylation of monosubstituted ureas has been studied in the presence of aldehydes and using molecular hydrogen as a clean reductant. Unsymmetrical N,N-disubstituted ureas were formed in good to excellent isolated yields (60-93%) without the production of salt waste. This reaction was incorporated to a one-pot, solvent-free sequence involving the alkylation of monosubstituted ureas generated in situ from the corresponding amines.