Metal-free annulation/aerobic oxidative dehydrogenation of cyclohexanones with o-acylanilines: efficient syntheses of acridines

Abstract

We have identified metal-free reaction conditions for the annulation/aerobic oxidative dehydrogenation of cyclohexanones with o-acylanilines to the corresponding acridine derivatives. The combination of trifluoroacetic acid (TFA), tert-butyl hydroperoxide (TBHP), dimethylsulfoxide (DMSO) and oxygen (O₂) converted the cyclohexanone derivatives to an aromatic aryl product in moderate to good yields. The experimental results suggest that this process involves an aza-allyl oxidation intermediate.