The Confined Cavity of a Coordination Cage Suppresses the Photocleavage of α‐Diketones To Give Cyclization Products through Kinetically Unfavorable Pathways

It's a trap: The photochemical homolytic cleavage of an α-diketone leading to degradation products was suppressed through the encapsulation of the diketone in a self-assembled cage. Instead, intramolecular cyclization products were formed through otherwise unfavorable (kinetically hidden) reaction pathways. This provides an approach to find new reactions of photolabile compounds that had been abandoned because of predominant cleavage reactions.