One-pot synthesis of nitrones from primary amines and aldehydes catalyzed by methyltrioxorhenium.

One-pot condensation/oxidation of primary amines and aldehydes using urea-hydrogen peroxide (UHP) as the stoichiometric oxidant in the presence of methyltrioxorhenium (MTO) as catalyst affords nitrones in a simple and regioselective manner. UHP is a practical and safe source of H2O2, and its use here instead of aqueous H2O2 solutions also simplifies greatly the workup procedure as extractions with organic solvents can be avoided. Typically, at the end of the reaction the solid urea is simply filtered off. From a sustainability point of view, this one-pot synthesis is simple to perform, takes place under mild conditions, has a high atom economy, and releases water as the only by-product.