Hydrochloric Acid → 4-(4-Bromo-1H-pyrazol-1-yl)piperidine

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Reaction Steps

A 4 M solution of HCl in 1,4-dioxane (13.5 ml, 54 mmol) is added to a solution of 4-(4-Bromo-pyrazol-1-yl)-piperidine-1-carboxylic acid tert-butyl ester (as obtained in preparation 62, 5.92 g, 17.94 mmol) in CH2Cl2 (50 ml) and the reaction mixture is stirred at RT for 6 h. The suspension is filtered on a Por. 4 Fritte and the cake dissolved in EtOAc. A saturated solution of NaHCO3 is added and the phases are separated. The aqueous phase is extracted 3× with EtOAc. The combined organic layers are washed with NaHCO3, brine, dried over Na2SO4, filtered and the filtrate is concentrated in vacuo. The residue is used without further purification in the next step, and afford the title compound as pale orange solid, Rt=0.582 min (Acquity HPLC BEH C18, 2.1×50 mm, 1.7 micron, detection 215 nM, 0.1 min 2% CH3CN in H2O, 2% to 100% CH3CN in H2O in 1.5 min, 0.4 min 100% CH3CN+0.1% TFA, flow rate 1.0 ml/min); MS: 330 (M+1, 79Br)+

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