Hydrochloric Acid → [1-Hydroxy-4-methyl-6-(pyrazin-2-yloxy)-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of [1-hydroxy-4-methyl-6-(pyrazin-2-yloxy)-1,3-dihydro-benzo[c][1,2]-oxaborol-3-yl]-acetic acid ethyl ester (0.250 g, 0.762 mmol) in methanol (5 mL) was added a solution of LiOH (0.091 g, 3.81 mmol) in water (4 mL) at 0° C. The resulting mixture was stirred at 0° C. for 3 hours. The reaction mixture was acidified to pH 2 using 6M HCl and extracted with EtOAc. The organic extracts were washed with brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by silica gel flash column chromatography (DCM/MeOH/AcOH=20:1:trace) to give pure product as a white powder after lyophilization (0.150 g, 65.6%). mp 156-157° C. 1HNMR (400 MHz, DMSO-d6 δ 9.20 (s, 1H), 8.53 (d, J=1.17 Hz, 1H), 8.35 (d, J=2.64 Hz, 1H), 8.19 (dd, J=2.63, 1.46 Hz, 1H), 7.25 (d, J=2.05 Hz, 1H), 7.10 (d, J=1.46 Hz, 1H), 5.51 (dd, J=9.51, 2.20 Hz, 1H), 3.07 (dd, J=15.52, 2.63 Hz, 1H), 2.28 (s, 3H), 2.13 (dd, 1H). MS (ESI) m/z=301 [M+H]+.

Provenance & Evidence