Azonia-azulenes. Part 6. Photochemical addition of alcohols to 10H-azepino[1,2-a]indoles

Abstract

Irradiation of solutions of the azepinoindole (1) in methanol or ethanol gives the 6- and 9-alkoxy-6,9-dihydroazepinoindoles (5), (24), (4), and (23); the other major products are the benzo[b]cyclobuta[hi]indolizines (6) and (25). Other substituted azepinoindoles (7)–(10) give correspondingly substituted methanol addition products. The 8-methylazepinoindole (9) also gives an 8,9-dihydro-8-methoxyazepinoindole (18), and the 7,9-dimethylazepinoindole (10) gives a 6,7-dihydro-7-methoxyazepinoindole (22). A mechanism is proposed for these reactions, and some confirmatory evidence provided by the irradiation of the azepinoindole (1) in methan[²H]-ol. The azepinoindoles (9) and (10) were synthesized by decomposition of the corresponding o-azido-phenylmethylbenzene.