tert-Butanol → [6-(5-tert-Butoxycarbonylamino-thiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 2-(3-ethoxycarbonylmethyl-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-6-yloxy)-thiazole-5-carboxylic acid (500 mg, 1.33 mmol) in tBuOH (10 mL) was added diphenylphosphoryl azide (0.35 mL, 1.61 mmol) and triethylamine (0.41 mL, 2.95 mmol), the reaction mixture was heated to 95° C. for 1 h. The solvent was removed under vacuum and the residue was extracted with ethyl acetate. The organic portion was washed with water and brine, and dried over Na2SO4 and concentrated. The residue was purified by column chromatography (silica, DCM/MeOH=20:1) affording the title compound (270 mg, 45%) as a white solid. 1H NMR (CDCl3) δ 7.35 (s, 1H), 7.10 (s, 1H), 6.79 (s, 1H), 5.61 (dd, 1H), 4.17 (q, 2H), 3.02 (dd, 1H), 2.37 (m, 1H), 2.30 (s, 3H), 1.48 (s, 9H), 1.23 (t, 3H).

Provenance & Evidence