Ring opening and ring closure reactions of chromone-3-carboxylic acid: unexpected routes to synthesize functionalized benzoxocinones and heteroannulated pyranochromenes

Authors: MAGDY AHMED IBRAHIM, TARIK EL-SAYED ALI

Abstract: Unexpected routes to synthesize functionalized benzoxocinones and heteroannulated pyranochromenes were achieved via transformations of the \gamma-pyrone ring in chromone-3-carboxylic acid throughout its reactions with some acyclic and cyclic carbon nucleophiles. A key part of the reaction mechanisms is discussed. Structures of the new synthesized products were established on the basis of elemental analysis and spectral data (IR, MS, and ^1H and ^{13}C NMR).

Keywords: Chromone-3-carboxylic acid, benzoxocinone, pyranochromenes, ring expansion, carbon nucleophiles

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