[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([NH:9][C:10](=[O:16])[O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[C:5]([CH3:17])[CH:4]=1.[CH:18]([Li])(CC)[CH3:19].O.Cl.[O:25]1[CH2:29][CH2:28][CH2:27][CH2:26]1>>[C:12]([O:11][C:10](=[O:16])[NH:9][C:6]1[CH:7]=[CH:8][C:3]([O:2][CH3:1])=[CH:4][C:5]=1[CH2:17][CH:29]([CH:28]1[CH2:19][CH2:18][CH2:26][CH2:27]1)[OH:25])([CH3:13])([CH3:14])[CH3:15]To a solution of tert-butyl (4-methoxy-2-methylphenyl)carbamate (475 mg) in tetrahydrofuran (7 mL) was added dropwise sec-butyllithium (1.04 mol/L hexane-cyclohexane solution, 4.3 mL) at −40° C. under an argon atmosphere, and the mixture was stirred for 15 minutes. Then a solution of cyclopentanecarboxyaldehyde (0.256 mL) in tetrahydrofuran (1 mL) was added dropwise, and the mixture was stirred at −40° C. for 15 minutes and at room temperature for additional one hour. Water and 1 mol/L hydrochloric acid were added to the reaction mixture and this resulting mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated saline, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluting solvent: ethyl acetate-hexane) to obtain the title compound (535 mg).
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