GENERAL PROCEDURE: A flame-dried and cooled round-bottomed flask under nitrogen protection was charged with allyl alcohol 51 (0.5 mmol) and tetrahydrofuran (THF, 2.5 mL). The reaction mixture was stirred at 0 °C for 5 min before a one-time addition of sodium hydride (NaH, 1 mmol, 2 equiv.), followed by a slow warming of the mixture to room temperature. Upon completion of the reaction, the reaction was quenched by the addition of saturated ammonium chloride (NH4Cl, 2 mL). The reaction mixture was extracted with ethyl acetate (EtOAc, 10 mL × 2) and the combined organic phases were washed with saturated saline (15 mL). The organic layer was dried over anhydrous magnesium sulfate (MgSO4) and concentrated under reduced pressure to remove the solvent, and the residue was purified by silica gel column chromatography to give the target ketone product 52.
