Pd-catalyzed double C–H bond activation of diaryl ketones for the synthesis of fluorenones

An efficient synthesis of fluorenones from diaryl ketones by Pd-catalyzed oxidative cyclization is described. A possible mechanism involving a carbonyl group assisted ortho-C–H activation and cyclometalation followed by a second C–H activation to form a six-membered palladacycle and reductive elimination is proposed.