[C:1](/[C:3](=[C:5]1/[C:6]2[CH:19]=[CH:18][C:17]([C:20](OC)=[O:21])=[CH:16][C:7]=2[O:8][CH2:9][C:10]2[CH:15]=[CH:14][CH:13]=[CH:12][C:11]/1=2)/[CH3:4])#[N:2].[BH4-].[Li+].Cl>C1COCC1>[OH:21][CH2:20][C:17]1[CH:18]=[CH:19][C:6]2=[C:7]([CH:16]=1)[O:8][CH2:9][C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][C:11]=1/[C:5]/2=[C:3](/[CH3:4])\[C:1]#[N:2][step 2] Methyl (E)-11-(1-cyanoethylidene)-6,11-dihydrodibenzo[b,e]oxepine-3-carboxylate (6.40 g, 21.0 mmol) was suspended in THF (105 mL), and the solution was added with lithium borohydride (2.29 g, 105 mmol), followed by stirring at 50° C. for 6 hr. Ice was added to the reaction mixture, and the mixture was neutralized with 1 mol/L hydrochloric acid to pH 2, and extracted twice with ethyl acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=30:70) to give the title compound (4.89 g, 17.6 mmol, 84.1%).
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