6-Hydroxy-4-oxo-4H-1-benzopyran-2-carboxylic acid ethyl ester synthesis

Yield:28466-95-7 42%

Reaction Conditions:

Stage #1: oxalic acid diethyl ester;2′,5′-dihydroxyacetophenonewith potassium etoxide in ethanol; for 1 h;Reflux;
Stage #2: with hydrogenchloride in ethanol;lithium hydroxide monohydrate;

Steps:

4.2.1. Synthesis of ethyl chromone-2-carboxylate derivatives

General procedure: Acetophenone (1 or 2) (2 g, 12 mmol) and diethyloxalate (28 mmol,4.09 g, 3.80 mL) were added to 10 mL of sodium ethoxide (21 wt %ethanol). The mixture was refluxed for 1 h. Concentrated HCl was thenadded dropwise until the reaction mixture was acidic. A precipitate wasformed, and the crude product was filtered and washed with ethyl ether.

References:

Reis, Joana;Fernandes, Carlos;Salem, Hoda;Maia, Marta;Tomé, Cláudia;Benfeito, Sofia;Teixeira, José;Oliveira, Paulo J.;Uriarte, Eugenio;Ortuso, Francesco;Alcaro, Stefano;Bagetta, Donatella;Cagide, Fernando;Borges, Fernanda [European Journal of Medicinal Chemistry,2022,vol. 239,art. no. 114507]