Synthesis of xanthones through the palladium-catalyzed carbonylation/C–H activation sequence

A series of xanthones with the dibenzo-γ-pyrone framework were synthesized through the palladium-catalyzed carbonylation/C–H activation sequence from the ortho diazonium salts of diaryl ethers in moderate to excellent yields. After screening the reaction condition, the optimal condition was 5 mol % tetrakis (triphenylphosphine) palladium (0) as the catalyst, potassium carbonate as the base, and toluene as the solvent in the presence of catalytic amount of tetrabutyl ammonium bromide under carbon monoxide atmosphere.