Br[CH2:2][C:3]1[O:4][CH:5]=[C:6]([OH:10])[C:7](=[O:9])[CH:8]=1.[NH:11]1[CH2:16][CH2:15][O:14][CH2:13][CH2:12]1>C(#N)C>[OH:10][C:6]1[C:7](=[O:9])[CH:8]=[C:3]([CH2:2][N:11]2[CH2:16][CH2:15][O:14][CH2:13][CH2:12]2)[O:4][CH:5]=12-(Bromomethyl)-5-hydroxy-4H-pyran-4-one 21 (5.0 g, 24.4 mmol), morpholine (4.3 mL, 48.8 mmol) and acetonitrile (120 mL) were charged in a 250 ml round-bottomed flask equipped with a magnetic stirrer. The reaction mixture was stirred for 3 h at 80° C. Acetonitrile was evaporated and the residu was extracted with EtOAc (400 mL). The organic layer was washed with water (20 mL), brine (2×20 mL), dried over MgSO4, filtered and evaporated to dryness. Diethyl ether (25 mL) was added and the product was precipitated and filtered to give after drying 5-hydroxy-2-(morpholinomethyl)-4H-pyran-4-one 22 (4.8 g, 72% yield) as a white solid.
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