Ten agate grinding balls were filled in an agate mortar, quartz sand (1.50 g), 2-furan methanol (87 μL, 1.0 mmol), and m-chloroperoxybenzoic acid (mCPBA, 345 mg, 2.0 mmol) were added, and the mixture was ground for 30 min. After completion of the reaction, the mixture was diluted with distilled water (15 mL) and filtered. The filtrate was freeze-dried to remove water to afford 6-hydroxy-2H-pyran-3(6H)-one (3a, 108 mg, 95% yield) as a yellow solid. The product was characterized by 1H NMR (400 MHz, CDCl3): δ = 6.96 (dd, 1H, J = 3.1,10.4 Hz, 5-H), 6.17 (d, 1H, J = 10.4 Hz, 4-H), 5.64 (d, 1H, J = 3.1 Hz, 6-H), 4.58 (d, 1H, J = 16.9 Hz, 2-H). 4.14 (d, 1H, J = 16.9Hz, 2-H).
