N-Boc-3-methylsulfonyloxyazetidine (304 mg, 1.21 mmol), 4-bromopyrazole (178 mg, 1.21 mmol), a mineral oil suspension of 60% NaH (73 mg, 1.82 mmol), and 2 mL of DMF were added to the microwave tube.The reaction mixture was microwaved at 110 °C for 30 min. Upon completion of the reaction, the mixture was partitioned between EtOAc (200 mL) and saturated NaHCO3 solution (2 × 50 mL) and washed with brine (50 mL). The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure to give 360 mg of the yellow oily product tert-butyl 3-(4-bromo-1H-pyrazol-1-yl)azetidine-1-carboxylate in 98% yield.1H NMR (400 MHz, DMSO-D6) δ ppm 1.36-1.43 (m, 9H), 4.08 (s, 2H), 4.18- 4.31 (m, 2H), 5.12-5.22 (m, 1H), 7.67 (s, 1H), 8.14 (s, 1H).
