Novel 2,4-methanoadamantane-benzazepine by domino photochemistry of N-(1-adamantyl)phthalimide

The photochemical reaction of N-(1-adamantyl)phthalimide (1) gives cleanly one product, the novel hexacyclic benzazepine derivative of 2,4-methanoadamantane 2. Its structure was characterized by spectroscopic methods and X-ray analysis and represent the first example of the 2-azahexacyclo[8.7.1.1 (1,4).0 (4,9).0 (11,16).0 (12,18)]nonadeca-4,6,8-triene skeleton. The product is formed by a domino process of two consecutive excited-state intramolecular gamma-hydrogen-transfer reactions. Base hydrolysis of the benzazepine 2 gives in high yield the keto derivative of the 1,2-substituted adamantane epsilon-amino acid 3.