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.