[OH:1][C@@H:2]([CH3:11])[C:3]([N:5]1[CH2:10][CH2:9][O:8][CH2:7][CH2:6]1)=[O:4].[O:12]1[CH:17]=[CH:16][CH2:15][CH2:14][CH2:13]1>ClCCl.O.C1(C)C=CC(S(O)(=O)=O)=CC=1>[O:12]1[CH2:17][CH2:16][CH2:15][CH2:14][CH:13]1[O:1][C@@H:2]([CH3:11])[C:3]([N:5]1[CH2:6][CH2:7][O:8][CH2:9][CH2:10]1)=[O:4]A mixture of (S)-ethyl lactate (75 g) and morpholine (164 g) was heated at 80° C. for 64 hours. The reaction solution was concentrated and the residue was subjected to silica gel chromatography (eluent:hexane/ethyl acetate=4/1 to ethyl acetate) to give 4-[(S)-2-hydroxypropionyl]-morpholine (69.4 g) as a pale yellow oily substance. p-Toluenesulfonic acid monohydrate (0.82 g) was added to a solution of 4-[(S)-2-hydroxypropionyl]morpholine (69.4 g) in dichloromethane (300 ml), to which 3,4-dihydro-2H-pyran (40.3 g) was added dropwise at ice-bath temperature. The reaction solution was stirred at 0° C. for 30 minutes and washed with a 5% aqueous solution of sodium bicarbonate. After the organic layer was dried over anhydrous magnesium sulfate and concentrated, the residue was subjected to silica gel chromatography (eluent:hexane/ethyl acetate=8/1 to ethyl acetate) to give 4-[(2S)-2-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)propionyl]morpholine (89.1 g) as a pale yellow oily substance.
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