A solution of (2S)-2-methyltetrahydro-2H-pyran-4-ol (27.3 g, 235 mmol) in acetone (980 mL) was cooled in an ice bath and treated drop-wise with Jones reagent (2.5 M, 103 mL, 258 mmol). The reaction mixture was stirred for 10 minutes at 0 °C and then warmed to room temperature. After 30 minutes, the mixture was cooled to 0 °C. 2-Propanol (18 mL, 240 mmol) was added and stirred for 30 minutes. After the mixture had been concentrated in vacuo, the residue was partitioned between water and dichloromethane. The aqueous layer was extracted 3 times with dichloromethane, and the combined organic layers were dried over magnesium sulfate, filtered, and concentrated under reduced pressure to provide the product 2-methyloxan-4-one.
