Cesium carbonate → 1-(2-Methoxyethyl)-1H-pyrazole-4-boronic acid, pinacol ester

Participants

Reaction Steps

4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (100 mg, 0.52 mmol), 1-chloro-2-methoxyethane (0.056 mL, 0.62 mmol) and cesium carbonate (252 mg, 0.73 mmol) in DMF (1 mL) were heated in microwave reactor at 160° C. for 30 min. The reaction mixture was concentrated under reduced pressure and purified by silica gel chromatography (ISCO, hexanes/ethyl acetate 0-100% over 15 min) to isolate Compound B162a (130 mg, 100% yield). HPLC: RT=1.0 min (LCMS Method M). MS (ES): m/z=253.0 [M+H]+. 1H NMR (500 MHz, CHLOROFORM-d) δ 8.04 (s, 1H), 7.83 (d, J=18.4 Hz, 1H), 4.37 (t, J=5.2 Hz, 1H), 3.78 (t, J=5.2 Hz, 1H), 3.38-3.31 (m, 2H), 2.98 (s, 3H), 2.90 (s, 3H), 1.34 (s, 6H), 1.26 (s, 3H).

Provenance & Evidence