One‐Pot Transformation of Methylarenes into Aromatic Aldehydes under Metal‐Free Conditions

On the basis of studies of the transformation of benzylic bromides into the corresponding aromatic aldehydes by treatment with N‐methylmorpholine N‐oxide, various methylarenes were treated either with DBDMH in the presence of AIBN in acetonitrile at reflux (Method A) or with NBS in CCl4 under irradiation with a tungsten lamp at 30 °C (Method B), followed by treatment with N‐methylmorpholine N‐oxide to provide aromatic aldehydes in good yields. These methods could be adopted in one‐pot transformations of methylarenes into aromatic aldehydes under conditions free of less toxic reagents and transition metals.