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

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Reaction Steps

To a solution of (1-hydroxy-6-methoxy-4-methoxymethyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid ethyl ester (60 g, 0.20 mmol) in THF (3 mL) and H2O (2 mL) was added LiOH (0.048 g) at 0° C. The resulting mixture was stirred at room temperature for 2 hours then cooled to 0° C. and acidified to pH 3 with 6N HCl. The mixture was concentrated in vacuo and the residue purified by silica gel flash column chromatography to give (1-hydroxy-6-methoxy-4-methoxymethyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid (0.050 g, 90%). 1H NMR (400 MHz, DMSO-d6) δ 7.12 (s, 1H), 6.94 (s, 1H), 5.56 (m, 1H), 4.40 (m, 2H), 3.75 (s, 3H), 3.26 (s, 3H), 3.00 (m, 1H), 2.02 (m, 1H). MS (ESI) m/z: 235 [M−1]−. HPLC purity: 86% (220 nm), 96% (Maxplot).

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