Lithium Hydroxide → tert-butyl 4-(1H-pyrazolo[3,4-b]pyridin-4-yl)piperazine-1-carboxylate

Participants

Reaction Steps

TFA (6 mL) was added to tert-butyl 4-(1-(4-methoxybenzyl)-1H-pyrazolo[3,4-b]pyridin-4-yl)piperazine-1-carboxylate (1.59 g, 3.754 mmol) in DCM (30 mL) and stirred at room temperature for 1 hour. The reaction was then concentrated to dryness and dried under vacuum for 3 hours. TFA (8.68 mL, 112.6 mmol) was added, and the mixture was heated at 65° C. for 2 hours. The reaction was then concentrated to dryness. The resulting residue was added to THF (10 mL), a LiOH solution (3.8 mL, 7.5 mmol, 2N) and Boc2O (0.98 g, 4.50 mmol) and stirred at room temperature for 1 hour. Ether (20 mL) and water (10 mL) were then added. The organic layer was separated, washed with brine, and dried over sodium sulfate. After removal of solvent, the resulting residue was purified by chromatography (hexane:ethyl acetate, 3:1) to give tert-butyl 4-(1H-pyrazolo[3,4-b]pyridin-4-yl)piperazine-1-carboxylate (0.55 g, 48%) as a solid. MS APCI (+) m/z 304.1 detected. 1H NMR (400 Hz, DMSO-d6) δ 8.21 (s, 1H), 8.08 (d, J=5.6 Hz, 1H), 6.37 (d, J=5.6 Hz, 1H), 3.60 (m, 4H), 3.54 (m, 4H), 2.50 (s, 9H).

Provenance & Evidence