Reactivity and Decay Pathways of Photoexcited Anilinonaphtalenes

Article abstract of DOI:10.1021/ja00387a018

N-Methyl-2-anilinonaphthalene (2-MAN) is converted by light into 7-methyl-7H-benzocarbazole (7-MBC) and 5-methyl-6,7-dihydro-5H-benzocarbazole (9).The reaction takes place only in the absence of oxygen and is regioselective; i.e., the isomeric 5-methyl-5H-benzocarbazole (5-MBC) is not formed.Ring closure takes place from the excited triplet state of 2-MAN and a zwitterionic intermediate was found in flash experiments.N-Methyl-2-anilino-6-naphthalenesulfonate (2-MANS) behaves similarly.Caution should therefore be exercised if such compounds are used as fluorescence probes.N-Methyl-1-anilinonaphthalene (1-MAN) is photochemically more stable than 2-MAN.