[OH:1][C:2]1[CH:3]=[CH:4][C:5]2[CH:6]3[CH:14]([CH2:15][CH2:16][C:17]=2[CH:18]=1)[CH:13]1[C:9]([CH3:33])([C:10](=[O:32])[C:11](=[CH:19][C:20]2[CH:25]=[C:24]([O:26][CH3:27])[C:23]([O:28][CH3:29])=[C:22]([O:30][CH3:31])[CH:21]=2)[CH2:12]1)[CH2:8][CH2:7]3.[BH4-].[Na+].C(OCC)(=O)C.O>C1COCC1.CO>[CH3:33][C:9]12[CH2:8][CH2:7][CH:6]3[CH:14]([CH2:15][CH2:16][C:17]4[CH:18]=[C:2]([OH:1])[CH:3]=[CH:4][C:5]=43)[CH:13]1[CH2:12][C:11](=[CH:19][C:20]1[CH:21]=[C:22]([O:30][CH3:31])[C:23]([O:28][CH3:29])=[C:24]([O:26][CH3:27])[CH:25]=1)[CH:10]2[OH:32]A solution of 3-Hydroxy-13-methyl-16-(3,4,5-trimethoxy-benzylidene)-6,7,8,9,11,12,13,14,15,16-decahydro-cyclopenta[a]phenanthren-17-one (448 mg, 1.0 mmol, CAB01124) in THF/methanol (1:1, 40 ml) was cooled to 0° C. (ice bath) and sodium borohydride (100 mg, 2.64 mmol) was added. The reaction mixture was stirred for 2 h at this temperature, while it was turning from slightly yellow to colourless. The solution was transferred into a separation funnel and ethyl acetate (100 ml) and water (100 ml) were added. The organic layer was separated, washed with water (50 ml) and brine (50 ml), dried over sodium sulphate and concentrated under reduced pressure. Yield 445 mg (99%) white solid. 1H-NMR (CDCl3, 400 MHz), δ: 0.74 (s, 3H), 1.20-1.60 (m, 6H), 1.90-1.98 (m, 1H), 2.01-2.08 (m, 1H), 2.21-2.41 (m, 3H), 2.74-2.90 (m, 3H), 3.86 (s, 3H), 3.89 (s, 6H), 4.15 (d, J=9.4 Hz, 1H, H-17), 4.62 (s, 1H, —OH), 6.49-6.51 (m, 1H), 6.59 (d, J=2.3 Hz, 1H), 6.63-6.68 (m, 3H), 7.18 (d, J=8.2 Hz, 1H). LRMS (FAB+): 451.3 (100, [M+H]+).
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