Synthesis of xanthones from 4-(2-phenoxyphenyl)-1-tosyl-1H-1,2,3-triazole via rhodium-catalyzed annulation/oxidation

A series of xanthone derivatives were synthesized by rhodium-catalyzed cycloaddition and sequential oxidation. The derivatives synthesized for excellent yields, including electron-withdrawing and electron-donating substituents, demonstrated the wide applicability of the proposed approach. The xanthones synthesized with different substituent electron effects may go through the same intermediate via two cycloadditions. It is highlighted that the protocol was exemplified by its successful integration into a one-pot synthesis directly from 1-ethynyl-2-phenoxybenzene. We believe that the current method may be an attractive option for the synthesis of xanthone and its derivatives.