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

Participants

Reaction Conditions

Reaction Steps

4-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (19.4 g, 0.10 mol), 1-bromo-2-methoxy-ethane (14.18 ml, 0.15 mol), and caesium carbonate (32.58 g, 0.1 mol) are dissolved in DMF (200 ml). The suspension is stirred for 16 h at 80° C., filtered and the solvent is removed in vacuum. The residue is treated with tert-butyl methyl ether (200 ml), filtered over Celite and then the solvent is removed in vacuum; yield: 25.4 g 1-(2-methoxy-ethyl)-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-pyrazole; HPLC/MS: 1.82 min, [M+H]=253.

Provenance & Evidence