Efficient palladium-catalyzed C(sp2)-H activation towards the synthesis of fluorenes

A facile protocol for the synthesis of fluorene derivatives has been developed through palladium-catalyzed cyclization of 2 '-halodiarylmethanes via activation of arylic C-H bonds. The reactions occurred smoothly and allowed both electron-rich and electron-deficient substrates to convert into their corresponding fluorenes in good to excellent yields. Studies revealed that this Pd-catalyzed cyclization was also available for the substrates of 2 '-chlorodiarylmethanes and no catalyst poisoning occurred for 2 '-iododiphenylmethane.