Example 1 (Synthesis of pyran-4-one): In a 10 mL glass reaction flask fitted with a stirring device and a dropping funnel, 1.0 g (4.8 mmol) of 1,1,5,5-tetramethoxypentan-3-one (CAS: 159015-78-8) was added. Under cooling in an ice bath, 1.2 mL (14.1 mmol) of 12 mol/L hydrochloric acid solution was slowly added dropwise to the reaction flask. After the dropwise addition, the reaction mixture was stirred at room temperature for 4 hours. Upon completion of the reaction, the reaction solution was analyzed by gas chromatography (internal standard method) to confirm the formation of 0.45 g (yield: 97%) of pyran-4-one.
