Photochemical entry into the tetracyclo[4,4,0,03,904,8]decane ring system

Abstract

Irradiation of the duroquinone–trans,trans-hexa-2,4-diene exo Diels-Alder adduct (III) gives high yields of products (IV) and (V) formed via initial hydrogen abstraction; in contrast, irradiation of the corresponding endo Diels–Alder adduct (VI), in which hydrogen abstraction is sterically impeded, affords quantitatively the cage compound (VIII), a derivative of the tetracyclo[4,4,0,0^3,9,0^4,8]decane-2,5-dione ring system.