Small and Medium Rings, 76. Photorearrangement of Polycyclic Quinoxalines, Isomerisations of Isodrin‐Type and Aza‐Di‐π‐Methane Chromophores

The multichromophoric polycyclic quinoxaline 11 has been synthesized starting with diketone 7 . Irrespective of whether quinoxaline 11 is irradiated in its nπ ☆ or ππ ☆ band, the photoproduct formed in high yield is invariably the cage compound 14 . This excitation energy transfer from the quinoxaline to the isodrin subchromophore of 11 is facilitated by a strong mixing of energy levels in these two fragments of 11 , as evidenced by the PE spectrum of quinoxaline 13 . The direct interaction of a quinoxaline chromophore with a nonconjugated double bond, i.e. an aza‐di‐π‐methane rearrangement, is shown to occur photochemically in bicyclic quinoxaline 12 .