Oxidative Rearrangement Coupling Reaction for Functionalization of Tetrahydro-β-carbolines with Aromatic Amines.

The observation of an unexpected oxidative rearrangement coupling reaction led to the development of a novel method for the efficient functionalization of tetrahydro--carbolines (THCs). The treatment of THCs with photogenerated singlet oxygen (O-1(2)) afforded unstable dioxetanes, which underwent further transformation to form new bonds in the presence of trifluoroacetic acid. This operationally simple protocol exhibits broad functional-group tolerance and is suitable for the late-stage functionalization of complex druglike molecules.