[CH2:1]([N:3]1[C:7]2=[N:8][C:9]([CH2:24][CH3:25])=[C:10]([C:19](OCC)=[O:20])[C:11]([NH:12][CH:13]3[CH2:18][CH2:17][O:16][CH2:15][CH2:14]3)=[C:6]2[CH:5]=[N:4]1)[CH3:2].CO.[BH4-].[Li+].O>C1COCC1>[CH2:1]([N:3]1[C:7]2=[N:8][C:9]([CH2:24][CH3:25])=[C:10]([CH2:19][OH:20])[C:11]([NH:12][CH:13]3[CH2:14][CH2:15][O:16][CH2:17][CH2:18]3)=[C:6]2[CH:5]=[N:4]1)[CH3:2]To ethyl 1,6-diethyl-4-(tetrahydro-2H-pyran-4-ylamino)-1H-pyrazolo[3,4-b]pyridine-5-carboxylate (60.43 g, 174 mmol) in dry THF (300 mL) was added dry methanol (28.3 mL) followed by the addition of lithium borohydride (2M in THF, 262 mL, 523 mmol) over 30 min. The mixture was heated to reflux. After 1 h additional methanol (14.1 mL) was added. After a further 30 min additional methanol (14.1 mL) was added. After a further 30 min the mixture was cooled in an ice bath and treated with methanol (100 mL) followed (cautiously) with water (1000 mL). The mixture was stirred for 1 h and then extracted with dichloromethane (1,500 mL total). The combined organics were washed with water, then brine, dried and concentrated to dryness to afford 49.84 g of the title compound. LC-MS m/z 305 (M+H)+, 1.79 min (ret time).
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