[C:1]1([CH2:7][CH2:8][CH:9]=[C:10]2[CH2:15][CH2:14][N:13]([CH2:16][C:17]3[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=3)[CH2:12][CH2:11]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.B.O.S(=O)(=O)(O)[OH:26]>CCOCC.C1COCC1.CCN(CC)CC.CCOC(C)=O>[CH2:16]([N:13]1[CH2:12][CH2:11][CH:10]([C:9](=[O:26])[CH2:8][CH2:7][C:1]2[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=2)[CH2:15][CH2:14]1)[C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1
To a solution of 1.115 g 4-(3-phenylpropylidene)-1-benzylpiperidine from Step B in 40 mL anhydrous ether under nitrogen was added 11.5 mL 1M borane solution in THF with stirring. After stirring for three hours, 2 mL of water was added dropwise, and the mixture was stirred for 30 min. After cooling with ice, a solution prepared from 0.287 g chromic anhydride, 0.624 mL concentrated sulfuric acid and 15 mL water was added dropwise with vigorous magnetic stirring over 5 minutes. After stirring for an additional 5 minutes, the cooling bath was removed. After 1.5 hours more, 100 mL each of 0.5N NaOH & ether was added, and the mixture was stirred to disolve a solid residue. After separating the layers, the aqueous layer was extracted with 2×100 mL ether. The combined ether layer was washed with 100 mL each of EDTA, water, and saturated brine, dried over Na2SO4, and concentrated under reduced pressure to give a colorless gel. The oxidation step were then repeated with half of the reagent used above. Flash chromatography on silica gel with 30˜50% EtOAc in hexanes with 3% (v/v) Et3N gave 0.293 g of the title compound as a colorless gel. RF: 0.41 (30% EtOAc in hexanes having 3% (v/v) Et3N). 1H NMR (500 MHz, CDCl3): δ7.17˜7.33 (m, ˜10H), 3.51 (s, 2H), 2.88˜2.92 (m, 2H), 2.75˜2.80 (m, 2H), 2.26˜2.32 (m, 1H), 1.98˜2.04 (m, 2H), 1.76˜1.82 (m, 2H), 1.63˜1.72 (m, 4H). ESI-MS 308.1 (M+H), HPLC A: 2.45 min.
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