Hydrochloric Acid → Ethyl 2-(1,6-dihydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate

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Reaction Steps

To a solution of crude [1-hydroxy-4-methyl-6-(tetrahydro-pyran-2-yloxy)-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester in THF (30 mL), was added dilute hydrochloric acid (6M, 3 mL) at 0° C. The mixture was allowed to warm to room temperature over 1 hour then concentrated in vacuo. The residue was purified by silica gel flash column chromatography (EtOAc/hexane=1:1) to give the product as a light brown gum (2.1 g, 62%, 2 steps). 1H NMR (400 MHz, DMSO-d) δ ppm 9.21 (s, 1H), 9.01 (s, 1H), 6.86 (d, J=2.4 Hz, 1H), 6.64 (d, J=2.4 Hz, 1H), 5.40-5.37 (m, 1H), 4.02 (q, J=7.2 Hz, 2H), 3.35-3.01 (m, 1H), 2.19-2.13 (m, 4H), 1.10 (t, 3H). MS (ESI) m/z=251 [M+H]+.

Provenance & Evidence