Eosin Y–Yb(OTf)3 catalyzed visible light mediated electrocyclization/indole ring opening towards the synthesis of heterobiaryl-pyrazolo[3,4-b]pyridines

A catalytic combination of eosin Y-Yb(OTf)(3) has been developed to catalyse the visible light mediated synthesis of indole substituted heterobiaryl-pyrazolo[3,4-b]pyridines in good yields under mild reaction conditions. The current reaction proceeds through a dual, Lewis acid and oxidative photo-catalysis to afford the corresponding product at room temperature via electrocyclization and indole ring opening.