Methyl iodide → HCID 58155245, compound

A dried flask was charged under an argon atmosphere with a solution of the crude (2S,5R)-5-(3-bromo-phenyl)-4-(4-methoxy-benzyl)-2,5-dimethyl-morpholin-3-one (622 mg) in tetrahydrofuran (16 ml) which was cooled to −75° C. Lithium diisopropylamide (1.54 ml, 3 mmol) was rapidly added, followed by iodomethane (502 mg, 3.5 mmol). After 15 minutes at −75° C. the reaction was complete. For the workup, the cold reaction mixture was quenched with a saturated ammonium chloride solution (15 ml) and extracted with a mixture of dichloromethane (40 ml) and water (15 ml). The organic layer was dried over sodium sulfate and evaporated. The crude product was purified by chromatography on silica gel using a gradient of heptane and ethyl acetate=100/0 to 66/34 as the eluent. The (R)-5-(3-bromo-phenyl)-4-(4-methoxy-benzyl)-2,2,5-trimethyl-morpholin-3-one was obtained as a white solid (495 mg, 77% of theory). Mass (calculated) C21H24BrNO3 [418.334]; (found) [M+H]+=418, [M+2-H]+=420.