One-pot Synthesis of 2-Substituted 4H-Chromeno[3,4-d]oxazol-4-ones from 4-Hydroxy-3-nitrocoumarin and Acids in the Presence of Triphenylphosphine and Phosphorus Pentoxide under Microwave Irradiation
T. D. Balalas,
G. Stratidis,
D. Papatheodorou,
E.-E. Vlachou,
C. Gabriel,
D. J. Hadjipavlou-Litina,
K. E. Litinas
Affiliations
T. D. Balalas
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki
G. Stratidis
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki
D. Papatheodorou
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki
E.-E. Vlachou
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki
C. Gabriel
Center for Research of the Structure of Matter, Magnetic Resonance Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki
D. J. Hadjipavlou-Litina
Department of Pharmaceutical Chemistry, School of Pharmacy, Aristotle University of Thessaloniki
K. E. Litinas
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki
Abstract 2-Substituted 4H-chromeno[3,4-d]oxazol-4-ones are prepared from 4-hydroxy-3-nitrocoumarin and acids by one-pot reaction in the presence of PPh3 and P2O5 under microwave irradiation or by one-pot two-step reactions in the presence of Pd/C and hydrogen and then P2O5 under microwave irradiation. The fused oxazolocoumarins were also synthesized from 3-amido-4-hydroxycoumarins and P2O5 under microwave irradiation. The 3-amido-4-hydroxycoumarins are obtained almost quantitatively from 4-hydroxy-3-nitrocoumarin, acids and PPh3 under microwave irradiation, or in the presence of Pd/C and H2 on heating. Preliminary biological tests indicate significant inhibition of soybean lipoxygenase and antilipid peroxidation for both oxazolocoumarins and o-hydroxyamidocoumarins.
