Visible-Light-Initiated Palladium-Catalyzed Cross-coupling by PPh 3 Uncaging from an Azobenzene Ruthenium-Arene Complex.

Photo-release of triphenylphosphine from a sulfonamide azobenzene ruthenium-arene complex was exploited to activate Pd II Cl 2 into Pd 0 catalyst, for the photo-initiation of Sonogashira cross-coupling. The transformation was initiated on demand - by using simple white LED strip lights - with a high temporal response and the ability to control reaction rate by changing the irradiation time. Various substrates were successfully applied to this photo-initiated cross-coupling, thus illustrating the wide functional-group tolerance of our photo-caged catalyst activator, without any need for sophisticated photochemistry apparatus.