4-Bromopyrazole → tert-Butyl 4-(4-bromo-1H-pyrazol-1-yl)piperidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

NaH (60% in mineral oil, 1.36 g, 34 mmol) is added portionwise to a stirred solution of 4-bromopyrazole (4.58 g, 30.9 mmol) in DMF (20 ml). The resulting mixture is stirred for 1 h at 0° C. and 4-Methanesulfonyloxy-piperidine-1-carboxylic acid tert-butyl ester (as obtained in preparation 61, 8.62 g, 30.9 mmol) is added. The resulting pale suspension is heated at 100° C. for 1 h. The reaction is quenched with water and extracted with EtOAc several times. The combined organic layers are washed with brine, dried over Na2SO4, filtered and the filtrate is concentrated in vacuo. The residue is purified by chromatography on a 120 g silica gel column on a Combiflash Companion™ (Isco Inc.) apparatus (gradient hexanes: TBDME from 1:0=>0:1) to afford the title compound as a colorless solid, Rt=1.213 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)+.

Provenance & Evidence