Triethylamine → Tert-butyl 3-(methanesulfonyloxy)azetidine-1-carboxylate

Beteiligte Stoffe

Reaktionsschritte

To a solution of 1-BOC-3-hydroxyazetidine (1.0 g, 5.77 mmol), 4-dimethylaminopyridine (7 mg, 0.058 mmol) and triethylamine (0.880 mL, 6.35 mmol) in DCM (15 mL) cooled at 0° C. was added dropwise methanesulfonyl chloride (0.45 mL, 5.77 mmol). The RM was stirred 18 h at rt, diluted with DCM, washed with a solution of saturated NaHCO3 and brine. The organic layer was dried over Na2SO4, filtered and the solvent was removed under reduced pressure. 3-Methanesulfonyloxy-azetidine-1-carboxylic acid tert-butyl ester obtained as an oil was used directly in the next step. To a solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (1.4 g 5.57 mmol) in DMF (20 mL) stirred at 0° C. was added sodium hydride (55% in oil, 0.243 g, 5.57 mmol). After addition the mixture was stirred 1 h at rt, a solution of the above obtained 3-methanesulfonyloxy-azetidine-1-carboxylic acid tert-butyl ester (1.4 g, 5.57 mmol) in DMF (3 mL) was added. The RM was stirred 30 min at rt, and then 3 h at 95° C. After cooling at rt the mixture was poured in ice water and extracted with EtOAc. The combined organic phases were washed with a solution of saturated NaHCO3 and brine. The organic layer was dried over Na2SO4, filtered and the solvent was removed under reduced pressure. The residue was purified by flash chromatography (with heptane and EtOAc as eluants) to afford the title compound as an oil (tR 4.33 min (conditions 3), MH+=350.1)

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