Photochemical Cycloisomerizations via 7-exo-dig Reactions on a Calix[4]arene Scaffold

Abstract
Narrow-rim 1,3-bis(phenylethynyl)-p-tert-butylcalix[4]arenes were found to be photolabile, producing unprecedented seven-membered oxacyclic systems formed via 7-exo-dig cyclizations and a new [3.2.1]bicyclic system via subsequent 1,8-H shifts. The calixarene provided a scaffold for these unprecedented photochemical reactions to occur.