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.