Photoactivated Transition-Metal Triggers for Ambient Temperature Enediyne and Dienyne Cyclization: Ruthenium‑η6‑Naphthalene Complexes

A persistent challenge confronting potential applications of the Bergman cycloaromatization reaction is the development of methods for spatiotemporal control of diradical formation. Photochemical variants (photo-Bergman cycloaromatizations) have thus far met with limited success, failing completely in the case of acyclic enediynes. Here we describe the development of efficient photoactivated transition-metal complexes that allow for spatiotemporal control of enediyne cycloaromatization at ambient temperatures. This strategy relies on air- and moisture-stable ruthenium naphthalene complexes that undergo photochemical dissociation of the naphthalene ligand, thereby generating coordination sites for enediyne binding and cycloaromatization. The same ruthenium naphthalene complexes also trigger dienyne cyclization under photochemical conditions.