Rh-catalyzed direct synthesis of 2,2′-dihydroxybenzophenones and xanthones

An efficient rhodium-catalyzed direct synthesis of 2,2'-dihydroxybenzophenones and xanthones was developed from functionalized salicylaldehydes. This approach provides an easy access to various functionalized 2,2'-dihydroxybenzophenone and xanthone core skeletons. This study also revealed the crucial role of the hydroxy group in the reductive homo-coupling process to generate 2,2'-dihydroxybenzophenones. Overall the outcome of the reaction course was also found to be influenced by the electronics of the substituent groups in salicylaldehydes.