Practical organic solvent-free Cu(OAc)2/DMAP/TEMPO-catalyzed aldehyde and imine formation from alcohols under air atmosphere

Abstract

A highly efficient and practical organic solvent-free Cu(OAc)₂/DMAP/TEMPO catalyst system for the selective aerobic oxidation of benzylic and allylic alcohols to aldehydes and phenones under an ambient air atmosphere was reported. A wide range of functional groups such as phenolic hydroxyl, amino, and methylthio are compatible with the catalyst system. The organic solvent-free aerobic oxidative imine synthesis from benzyl alcohol and amines was also achieved via the newly developed Cu(OAc)₂/DMAP/TEMPO catalyst. 100 g-scale reactions for aldehyde and imine formation were achieved with over 90% yield using 0.5 mol% catalyst loading in 36 hours, presenting a potential valuable protocol for both economical and environmental considerations.