Melamine trisulfonic acid as a highly efficient catalyst for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes under solvent-free conditions

Melamine trisulfonic acid (MTSA) is utilized as a highly efficient catalyst for the solvent-free condensation reaction of 2-naphthol with arylaldehydes under conventional thermal or microwave irradiation to give 14-aryl-14H-dibenzo[a,j]xanthenes in high to excellent yields and in short reaction times.