Nonsteroidal Antiinflammatory Agents, 4. Rearrangement Reactions of Heterocycles, 11. Ketenoid Rearrangement and Oxidation of 2-Pyrons to 1,4-Naphthoquinon-5-alkanoic acids

Article abstract of DOI:10.1007/BF00809687

Fused 2-pyrones 4, obtained by the thermal condensation of ketones 1 with reactive malonates 2, rearrange above 200 deg C to yield condensed dihydroxynaphthalines 5.The latter compounds can be oxidized to give 3-hydroxy-1,4-naphthoquinone-5-alkanoic acids.The reaction of ketone 8 with magic malonates 2 or chlorocarbonyl ketene 9 affords the pyrones 11 in low yields.The 2-pyrones 11 could not be rearranged to 13; a possible explanation for this behaviour is presented. - Keywords: Trichlorophenyl malonates; 2-Pyrone synthesis; Carbonyl ketenes as intermediates; Hydroxy-1,4-naphthoquinone alkanoic acids