Hydrochloric Acid → 2-(6-(5-Carbamimidoylthiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetic acid

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The crude ethyl 2-(6-(5-carbamimidoylthiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate in 6 ml methanol was treated with aqueous NaOH solution (500 mg, 6 ml water) for one hour. It was acidified with 1N HCl to pH 5 and then concentrated. HPLC purification gave desired product as white flakes. 1H NMR (400 MHz, DMSO-d6) δ 12.4 (b, 1H), 9.22 (b, 2H), 9.01 (b, 2H), 8.21 (s, 1H), 7.44 (d, J=2 Hz, 1H), 7.32 (d, J=1.6 Hz, 1H), 5.50 (dd, J=9.2, 2.4 Hz, 1H), 3.05 (dd, J=15.6, 2.4 Hz, 1H), 2.28 (s, 3H), 2.12 (dd, J=15.6, 9.6 Hz, 1H). MS (ESI) m/z=348 [M+H]+.

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