269410-08-4

7051-34-5

1000801-75-1

General procedure for the synthesis of 1-(cyclopropylmethyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole from 4-pyrazolylboronic acid pinacol ester and bromomethylcyclopropane: Bromomethylcyclopropane (0.95 mg, 6.70 mmol, 0.70 mL, 95%) was added to a solution containing 4-(4,4,5, 5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole at 0°C. 5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (1.00 g, 5.15 mmol) and cesium carbonate (3.49 mg, 10.72 mmol) in a mixture of anhydrous N,N-dimethylformamide (20 mL). After stirring for 30 min, the ice water bath was removed. The reaction mixture was stirred overnight at room temperature. Subsequently, the reaction mixture was diluted with ethyl acetate (150 mL) and washed with brine (3 x 100 mL). The organic layer was dried with sodium sulfate and concentrated in vacuum to afford 1.30 g (4.38 mmol, 85% yield) of the target compound 1-(cyclopropylmethyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole.GC-MS (Method L9): rt = 4.35 min; m/z = 247. 1H NMR (300 MHz, CDCl3, Method M2) δ 7.81 (s, 1H), 7.79 (s, 1H), 3.99 (d, J = 7.1 Hz, 2H), 1.32 (s, 12H), 1.27 (m, 1H), 0.71-0.58 (m, 2H), 0.41-0.33 (m, 2H).