Direct Formation of a Substituted [5.5.5.5]Fenestrane by Intramolecular Arene‐Olefin Photocycloaddition

Abstract
In a search for further synthetic routes to substituted [5.5.5.5] fenestranes, compound 1a, a derivative of 7‐methoxyindane, was photolyzed. Two of the three photoproducts, viz. the [3.5.5.5]fenestrane 3a and the isomer 4a, are formed according to the expected intramolecular meta‐cycloaddition. A different mechanism is suggested for the formation of the major component 2a.