Tetrabutylammonium Fluoride → 5-hydroxy-3-methyl-1,3-benzoxazol-2(3H)-one

Participants

Reaction Steps

To a cooled (0° C.) solution of 5-{[tert-butyl(dimethyl)silyl]oxy}-3-methyl-1,3-benzoxazol-2(3H)-one (1.20 g, 4.3 mmol) in anhydrous tetrahydrofuran (15 mL) was added dropwise tetra-n-butylammonium fluoride (4.7 mL, 1 M in tetrahydrofuran, 4.7 mmol). The reaction mixture was stirred at ambient temperature for 16 h and concentrated in vacuo. To the residue was added ethyl acetate (10 mL) and a 1 M solution of hydrochloric acid (20 mL) and the resultant suspension was sonicated for 5 min. The product was collected by vacuum filtration, washed with ethyl acetate (10 mL), air-dried and dried under high vacuum to afford 5-hydroxy-3-methyl-1,3-benzoxazol-2(3H)-one (0.47 g, 67%) as a pink solid: 1H NMR (300 MHz, DMSO-d6) δ9.52 (br s, 1H), 7.09 (d, J=8.6 Hz, 1H), 6.62 (d, J=2.4 Hz, 1H), 6.47 (dd, J=8.6, 2.4 Hz, 1H), 3.27 (s, 3H); MS (ES−) m/z 164.2 (M−1).

Provenance & Evidence