A mixture of N-{[1,6-diethyl-4-(tetrahydro-2H-pyran-4-ylamino)-1H-pyrazolo[3,4-b]pyridin-5-yl]methyl}-N′-[(6-fluoro-3′-formyl-3-biphenylyl)methyl]-1,3-benzenedicarboxamide (150 mg, 0.226 mmol), 1,2-dimethylpiperazine (45.7 mg, 0.40 mmol), sodium triacetoxyborohydride (95 mg, 0.45 mmol) and AcOH (18 μl, 0.314 mmol) in 1,2-dichloroethane (DCE) (6 mL) was stirred overnight at room temperature. LC/MS showed that the reaction was complete. The reaction was diluted with EtOAc; the organic layer washed with dilute aq. NaOH, then sat. aq. NaCl and dried [Na2SO4], then concentrated to a viscous taffy. The material was purified on a Gilson HPLC using reverse phase (acetonitrile-water with 0.1% TFA). Fractions containing the desired product were combined, the MeOH removed, the aqueous layer treated with EtOAc and 1N NaOH. The mixture was vigorously extracted with EtOAc (2×), the extract was washed with a small amount of sat. aq. NaCl; dried [Na2SO4], then concentrated to a glassy, creamy tan, coloured foam (0.1002 g). LC-MS m/z 761.5 (M+H)+, 0.76 min (ret time).
