Cl.[O:2]1[C:6]2([CH2:11][CH2:10][N:9]([C:12]3[CH:20]=[CH:19][C:15]([CH:16]=[N:17][OH:18])=[CH:14][CH:13]=3)[CH2:8][CH2:7]2)[O:5][CH2:4][CH2:3]1.C([BH3-])#N.[Na+].[OH-].[Na+]>CN(C1C=CC(N=NC2C=CC(S(O)(=O)=O)=CC=2)=CC=1)C.O.CO>[OH:18][NH:17][CH2:16][C:15]1[CH:19]=[CH:20][C:12]([N:9]2[CH2:8][CH2:7][C:6]3([O:5][CH2:4][CH2:3][O:2]3)[CH2:11][CH2:10]2)=[CH:13][CH:14]=1Hydrochloric acid (4N, in dioxane) was added dropwise into a mixture of 4-(1,4-dioxa-8-azaspiro[4.5]dec-8-yl)benzaldehyde oxime (5.3 g, 20.24 mmol) (which was obtained in Example 51), sodium cyanoborohydride (6.3 g, 101.2 mmol), methyl alcohol(200 mL), and methyl orange (10 mg), until an acidic solution (pH about 4) was achieved. The mixture was then stirred for 1 hour, poured into water, neutralized with NaOH (2N) and extracted with ethyl acetate. The organic extracts were dried over MgSO4. Evaporation and purification by flash chromatography (hexanes/ethyl acetate/methyl alcohol 10/5/1) gave a white solid (4.2 g, 78% yield); mp 107-109° C,; 1H NMR (400 MHz, DMSO-d6) δ 1.64 (m, 4H), 3.20 (m, 4H), 3.74 (s, 2H), 3.90 (s, 4H), 5.84 (brs, 1H), 6.86 (m, 2H), 7.14 (m, 2H), 7.19 (brs, 1H); MS (ES) m/z: 265 (MH+).
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