Lithium Hydroxide → tert-butyl 4-(5-phenyl-1H-pyrazolo[3,4-b]pyridin-4-yl)piperazine-1-carboxylate

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Reaction Steps

TFA (3 mL) was added to tert-butyl 4-(1-(4-methoxybenzyl)-5-phenyl-1H-pyrazolo[3,4-b]pyridin-4-yl)piperazine-1-carboxylate (1.7 g, 3.40 mmol, see Example 1) in DCM (10 mL) and stirred at room temperature for 2 hours. The reaction was concentrated to dryness and dried under vacuum for 3 hours. TFA (13.1 mL, 170 mmol) was then added, and the mixture was heated at 65° C. for 1 hour. The reaction was then concentrated to dryness. The resulting residue was added to THF (10 mL), an aqueous LiOH solution (6.81 mL, 2M) and Boc2O (2.23 g, 10.2 mmol) and stirred at room temperature for 3 days. Ether (50 mL) was then added. The organic layer was separated, washed with brine, and dried over sodium sulfate. After removal of the solvent, the resulting residue was purified by column chromatography (hexane:ethyl acetate, 1:1) to give tert-butyl 4-(5-phenyl-1H-pyrazolo[3,4-b]pyridin-4-yl)piperazine-1-carboxylate (1.1 g, 85%) as a solid. MS APCI (+) m/z 380.1 detected.

Provenance & Evidence