An efficient and convenient manganese catalyst for the aerobic oxidative lactonization of diols without any additives

An efficient and convenient catalytic system for the aerobic oxidative lactonization of diols has been disclosed based on MnAl composite oxides (MnAlOx) and O2 without any additives in the study. This protocol is featured with simple catalytic system, as no any additives are needed, and it has high practical potential. The developed Mn-based reaction system can tolerate various diols with moderate to excellent yields of lactones. Based on a series of control experiments, a possible reaction path containing 2-(hydroxymethyl)benzaldehyde instead of 1,3-dihydroisobenzofuran as the predominant reaction intermediate has been proposed for the model lactonization of 1,2-benzenedimethanol. Electron transfer processes are probably taking place in the catalytic transformation based on a series of control experiments and characterization of the catalyst. The synergistic effect between Mn and Al was observed to be responsible for the high catalytic performance.