[CH:1]([C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=1[C:9]1[C:19]2[O:18][CH2:17][CH2:16][C:15]([C:20]([O:22][CH2:23][CH3:24])=[O:21])=[CH:14][C:13]=2[CH:12]=[CH:11][CH:10]=1)=[O:2].[BH4-].[Na+].Cl>C(O)C.O1CCCC1>[OH:2][CH2:1][C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=1[C:9]1[C:19]2[O:18][CH2:17][CH2:16][C:15]([C:20]([O:22][CH2:23][CH3:24])=[O:21])=[CH:14][C:13]=2[CH:12]=[CH:11][CH:10]=1To a solution of ethyl 2,3-dihydro-9-(2-formylphenyl)-1-benzoxepin-4-carboxylate (0.58 g) in a mixture of ethanol (5.8 ml) and tetrahydrofuran (3 ml) was added sodium borohydride (34 mg) at 0 C. The reaction mixture was stirred for 30 minutes at ambient temperature, thereto was added 1N hydrochloric acid (2 ml), and evaporated in vacuo. The residue was partitioned between ethyl acetate and water. The organic layer was washed successively with saturated aqueous sodium bicarbonate and brine, dried over anhydrous magnesium sulfate, and evaporated n vacuo. The residue was purified by medium pressure liquid chromatography (silica gel) using a mixture of ethyl acetate and n-hexane (1:9) as an eluent to give a solid of ethyl 2,3-dihydro-9-(2-hydroxymethylphenyl)-1-benzoxepin-4-carboxylate (530 mg).
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