Studies on photochemical rearrangement of non‐oxygenated bicyclo[2.2.2]octenones and mono‐oxygenated bicyclo[2.2.2]octenones from masked o‐benzoquinones: Access to protoilludane and marasmane skeletons

In this work, we described flexible approaches to protoilludane‐like (5,6,4‐tricyclic ring) and marasmane‐like (5,6,3‐tricyclic ring) skeletons with naturally occurring cis/anti/cis stereochemistry using photochemical rearrangement of bicyclo[2.2.2]octenones and Diels‐Alder reaction of masked o‐benzoquinones as the key steps. A flexible approach to protoilludane‐like (5,6,4‐tricyclic ring) and marasmane‐like (5,6,3‐tricyclic ring) skeletons is reported, and the naturally occurring cis/anti/cis stereochemistry on the polycyclic skeleton was established by key steps of photochemical rearrangement of bicyclo[2.2.2]octenones and Diels‐Alder reaction of masked o‐benzoquinones.