To a solution of [6-(2-chloro-pyrimidin-4-yloxy)-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester (0.5 g, 1.37 mmol) and (3-hydroxy-propyl)-carbamic acid tert-butyl ester (0.48 g, 2.75 mmol) in DMF at 0° C. was added NaH (0.2 g, 4.13 mmol). The reaction mixture was allowed to warm to room temperature and stirred for 12 hours. Saturated NH4Cl (10 mL) was added at 0° C. and the solution acidified to pH˜5 with dilute HCl. The mixture was extracted with EtOAc (2×10 mL) and the organic extracts washed with water (10 mL), dried and concentrated in vacuo. The residue was purified by silica gel flash column chromatography (DCM:MeOH 95:5) to give {6-[2-(3-tert-butoxycarbonylamino-propoxy)-pyrimidin-4-yloxy]-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl}-acetic acid ethyl ester (0.45 g, 65%). 1H NMR (400 MHz, DMSO): δ 9.10 (s, 1H), 8.41 (d, J=5.2 Hz, 1H), 8.22 (d, J=5.6 Hz, 1H), 7.24 (s, 1H), 7.09 (s, 1H), 5.51 (d, J=9.6 Hz, 1H), 4.02 (q, J=7.2 Hz, 2H), 3.93 (t, J=6.0 Hz, 2H), 3.07-3.02 (m, 3H), 2.28-2.27 (m, 1H), 2.26 (s, 3H), 1.77 (t, J=6.4 Hz, 2H), 1.33 (s, 12H), 1.11 (t, J=6.8 Hz, 3H). MS (ESI) m/z=502 [M+H]+.
