[2.2.2.2]/[2.1.1.1]Pagodanes and [1.1.1.1]/[2.2.1.1]/[2.2.2.2]Isopagodanes: Syntheses, Structures, Reactivities − Benzo/Ene- and Benzo/Benzo-Photocycloadditions
The established route to the [1.1.1.1]/[2.2.1.1]pagodanes (1, 2) has been applied to the construction of the homologous [2.2.2.2] and [2.1.1.1] skeletons (3, 7). Application of this synthetic scheme to the iso[1.1.1.1]/iso[2.2.1.1]/iso[2.2.2.2] structures (4−6) failed though; the crucial [6+6]benzo/benzophotocycloaddition step in the face-to-facebenzo/benzo intermediates (26a and b) − in contrast to