Water → 2,3-dihydro-8-hydroxy-4H-1-Benzopyran-4-one

2,3-Dihydro-8-methoxy-4H-1-benzopyran-4-one (7.59 g, 42.4 mmol) was dissolved in xylene (80 mL) followed by addition of anhydrous aluminum chloride (11.4 g, 85.5 mmol), and the mixture was stirred at 100° C. for 2 hours. After cooling, the reaction mixture was poured into iced water and extracted with ethyl acetate. The organic layer was washed with 1N-hydrochloric acid and saturated aqueous sodium chloride solution, dried over MgSO4, and filtered. The filtrate was concentrated under reduced pressure and the residue was crystallized from methanol-ethyl acetate-diethyl ether to provide 3.94 g of the title compound. Yield 56%.