Efficient hydrogenation of imines over Fe and ZnO powder in a self-neutralizing acidic CO2–H2O system

Abstract

An environmentally benign process was developed for the reduction of imines with iron and zinc oxide-promoted in the reversible CO₂–H₂O system without any acid additive or organic solvent. H₂O is thought to behave as the terminal hydrogen source. The reaction system could be inherently neutralized by the ready removal of CO₂, thus resulting in facile post-processing and disposal without waste. The highly flexible and chemo-selective reduction protocol affords the corresponding amines with other intact reducible substituents in good to excellent yields.