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

• Main Authors: T. D. Balalas, G. Stratidis, D. Papatheodorou, E.-E. Vlachou, C. Gabriel, D. J. Hadjipavlou-Litina, K. E. Litinas
• Format: Article
• Language: English
• Published: Georg Thieme Verlag KG 2018-04-01
• Series: SynOpen
• Subjects: oxazolocoumarins; pph3; reduction; phosphorus pentoxide; microwaves; pd/c
• Online Access: http://www.thieme-connect.de/DOI/DOI?10.1055/s-0036-1591977
• ISSN: 2509-9396

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.