Cesium carbonate → HCID 67252450, compound

Participants

Reaction Steps

To a solution of (1,6-dihydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid ethyl ester (1.6 g, 6.4 mmol) in anhydrous DMF (15 mL) was added cesium carbonate (5.2 g, 16.0 mmol) and 6-chloro-pyrazine-2-carbonitrile (0.89 g, 6.4 mmol). The resulting mixture was stirred at room temperature overnight then quenched with crushed ice. The pH was adjusted to 2 with 6M HCl and the mixture extracted with EtOAc (2×200 mL). The organic extracts were washed with water, brine, dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified by silica gel flash column chromatography (0-75% EtOAc in hexane) to give 6-(6-cyano-pyrazin-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid ethyl ester (1.6 g, 71%). 1H NMR 400 MHz (DMSO-d6) δ 9.30 (s, 1H), 8.93 (s, 1H), 8.90 (s, 1H), 7.33 (s, 1H), 7.18 (s, 1H), 5.58 (m, 1H), 4.05 (q, J=7.2, 2H), 3.17 (m, 1H), 2.40 (m, 1H), 2.33 (s, 3H), 1.13 (t, J=6.8 Hz, 3H).

Provenance & Evidence