DIEA (0.055 mL, 0.32 mmol) was added to a solution of (S)-3-(5-phenyl-4-(piperazin-1-yl)-1H-pyrazolo[3,4-b]pyridin-3-yloxy)propane-1,2-diol dihydrochloride (0.050 g, 0.079 mmol, see Example 15), (S)-2-(1-(tert-butoxycarbonyl)pyrrolidin-2-yl)acetic acid (0.018 g, 0.079 mmol) and TBTU (0.031 g, 0.095 mmol) in DCM (1 mL) and stirred at room temperature for 1 hour. The reaction was then concentrated to dryness, and the residue was dissolved in THF/MeOH (2 mL, 1:1), and an aqueous LiOH solution (1 mL, 2 M) was added. The mixture was stirred for 10 minutes. Ethyl acetate (20 mL) was then added, and the organic layer was separated, washed with brine (10 mL), and dried over sodium sulfate. After removal of the solvent, the residue was purified by column chromatography (ethyl acetate:MeOH, 20:1) to give tert-butyl(R)-3-(4-chlorophenyl)-1-(4-(3-((S)-2,3-dihydroxypropoxy)-5-phenyl-1H-pyrazolo[3,4-b]pyridin-4-yl)piperazin-1-yl)-1-oxopropan-2-ylcarbamate as a solid. The solid was then dissolved in DCM (1 mL), and TFA (0.4 mL) was added. The mixture was stirred at room temperature for 1 hour and concentrated to dryness. The resulting residue was dissolved in DCM (0.5 mL), and HCl in ether (1 mL, 2 N)) was added. The resulting solid was collected by filtration to give (1-(4-(3-((S)-2,3-dihydroxypropoxy)-5-phenyl-1H-pyrazolo[3,4-b]pyridin-4-yl)piperazin-1-yl)-2-((S)-pyrrolidin-2-yl)ethanone dihydrochloride (0.019 g, 43%). MS APCI (+) m/z 481.2 detected.
