Step 1: Methylmagnesium bromide (3.66 mL, 10.99 mmol) was slowly added dropwise via syringe to a solution of dihydro-2H-pyran-4(3H)-one (1 g, 9.99 mmol) in diethyl ether (50 mL) at 0 °C. The reaction was carried out by stirring for 1 hour. The reaction was kept at this temperature and stirred for 1 hour and then gradually warmed up to room temperature. Upon completion of the reaction, the reaction was quenched using saturated aqueous NaHCO3 and NH4Cl solutions followed by extraction with ether. The organic layers were combined, washed with brine, dried over anhydrous MgSO4, filtered and concentrated under reduced pressure to afford the crude product 4-methyltetrahydro-2H-pyran-4-ol (1 g, 86% yield) as an oil. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 3.82-3.73 (m, 2H), 3.73-3.66 (m, 2H), 1.74-1.64 (m, 3H), 1.54 (ddt, J = 13.7, 4.6, 2.1 Hz, 2H), 1.41 (br.s, 1H), 1.28 (s, 3H) .
