Efficient oxidation of arylmethylene compounds using nano-MnO2

Nano-MnO2 has been developed as an efficient and mild reagent for the high-yield oxidation of arylmethylene compounds to the corresponding aldehydes and ketones as well as benzylic ethers to esters. The reagent is conveniently prepared and shows reactivity superior to synthetic (Attenburrow) MnO2 and commercial MnO2 under both microwave and conventional conditions. Typical reactions are performed using 25 wt % of nano-MnO2 relative to the substrate, and the reagent can be recycled up to six times without significant loss of activity. The observed conversions correlate well with surface-water content in the different MnO2 samples, as determined by thermogravimetric analysis. (C) 2013 Elsevier Ltd. All rights reserved.