How is 2H-Chromene-3-carboxylic acid (CAS: 22649-28-1) typically synthesized?

2H-Chromene-3-carboxylic acid is typically synthesized via the condensation of chromone with acetic anhydride followed by acid work-up. This method provides a good yield and selectivity. Other routes include the oxidation of chromene-3-aldehyde followed by acylation with an appropriate acid chloride. Catalysts such as hydrogen peroxide and sulfuric acid are commonly used to facilitate the oxidation step.