Uniform, spherical Cu/chitosan beads prepared using a software-controlled flow system as a green and conveniently recyclable catalyst for the efficient synthesis of various imines in short reaction time.

Oxidative self-coupling of amines and cross-coupling with alcohols are important reactions for the synthesis of imines; however, catalytic systems for these reactions usually require expensive oxidant, complicated catalyst preparation, complex reaction set-up, and/or additives such as bases or cocatalysts. Here, we report that amorphous cerium-manganese (CeÀ Mn) oxides with hierarchical microsphere structure prepared by a facile method could exhibit excellent catalytic performance for the synthesis of various imines using air as the green oxidant under mild conditions. The CeÀ Mn oxide heterogeneous catalysts could also be easily recovered and efficiently recycled without significant loss of activities. The excellent activities and the reusability of the CeÀ Mn oxide microspheres offer potential advances in the synthesis of imine.