[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 mins. The mixture was heated to reflux. After 1 h additional methanol (14.1 mL) was added. After a further 30 mins additional methanol (14.1 mL) was added. After a further 30 mins the mixture was cooled in an ice bath and treated with methanol (100 mL) followed (cautiously) with water (1,000 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 evaporated 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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