A solution of tert-butyl 3-(5-(5-(2,6-difluorophenyl)-1-tosyl-1H-pyrrolo[3,2-b]pyridin-3-yl)pyridin-3-ylamino)piperidine-1-carboxylate (33 mg, 0.050 mmol) in THF (1 mL) was treated with NaOH 10N (0.050 mL, 0.500 mmol). The reaction was heated to reflux at 80° C. After 4 h, the solution was cooled to 23° C., concentrated in vacuo and purified by silica gel chromatography (eluent: 1-6% MeOH/DCM), affording tert-butyl 3-(5-(5-(2,6-difluorophenyl)-1H-pyrrolo[3,2-b]pyridin-3-yl)pyridin-3-ylamino)piperidine-1-carboxylate (21 mg, 83%). MS (ESI, pos. ion) m/z: 506.3 (M+1) A solution of tert-butyl 3-(5-(5-(2,6-difluorophenyl)-1H-pyrrolo[3,2-b]pyridin-3-yl)pyridin-3-ylamino)piperidine-1-carboxylate (21 mg, 0.042 mmol) in MeOH (1 mL) was treated with HCl, 5-6N in IPA (0.083 mL, 0.415 mmol). The reaction was heated to 50° After 1 h, the reaction was cooled to 23° C., and the product (as HCl salt) was free-based using a Silicycle Si-propylsulfonic acid ion exchange column (catalog # R51230B). The compound was diluted in MeOH and added to a pad of the resin (wetted and flushed with 10 mL MeOH). It was flushed with MeOH (50 mL), and then the product was “released” using 2.0 M NH3 in MeOH solution (50 ml). The final filtrate was concentrated, affording 5-(5-(2,6-difluorophenyl)-1H-pyrrolo[3,2-b]pyridin-3-yl)-N-(piperidin-3-yl)pyridin-3-amine MS (ESI, pos. ion) m/z: 406.2 (M+1).
