3-(4-phenoxyphenyl)-1-(4-piperidyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (Compound 2) (350 mg, 0.906 mmol), 1-tert-butoxycarbonyl-4-piperidone(198mg, 0.996 mmol), sodium triacetoxyborohydride (288 mg, 1.358 mmol) and glacial acetic acid(60 ul, 0.996 mmol) were mixed with 5 ml of 1,2-dichloroethane. After stirring at room temperature overnight, 2 ml of water was added followed by solid sodium bicarbonate until the pH reached about 8. The layers were separated and the aqueous layer was extracted with dichloromethane. The combined organic layer was washed, dried and evaporated. The residue was purified via flash column chromatography to give 254 mg of 1-[1-(1-tert-butoxycarbonyl-4-piperidyl)-4-piperidyl]-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine. 1H NMR (DMSO) 1.39(m, 13H), 1.75 (m, 2H), 1.91 (m, 2H), 2.17(m, 2H), 2.35 (m, 2H), 2.72 (m, 2H), 3.0 (m, 2H), 3.63 (m, 1H), 3.98 (m, 2H), 4.63 (m, 1H), 7.16 (m, 5H), 7.44 (m, 2H), 7.67 (d, J=8.60 Hz, 2H), 8.23 (s, 1H); LC/MS (MH+32 484).
