Temperature-Controlled Desulfonylative Condensation of α-Sulfonyl o-Hydroxyacetophenones and 2-Formyl Azaarenes: Synthesis of Azaaryl Aurones and Flavones.

Temperature-controlled intermolecular desulfonylative condensation of α-sulfonyl o-hydroxyacetophenones with 2-formyl azaarenes (pyridines and quinolones) provides azaaryl (pyridyl and quinolyl) aurones and flavones under warming and refluxing toluene reaction conditions via the formation of the intermediate of sulfonyl chroman-4-one. The uses of various solvents are investigated for facile and efficient transformation. A plausible mechanism is proposed.