Hydrochloric Acid → 6-Hydroxy-2H-1,4-benzoxazin-3(4H)-one

Participants

Reaction Steps

Sodium hydride (60%) (1.6 g, 39.68 mmol) was added to a THF solution of compound 47 (2.5 g, 12.4 mmol) at 0° C. The reaction mixture was warmed to room temperature and left for 12 h. Excess sodium hydride was destroyed by careful addition of ice-water. The crude reaction mixture was acidified by the addition 1M HCl. The reaction mixture was extracted in EtOAc (6×50 ml). Solvent was evaporated to yield a brownish solid which was used for the next step without further purification. Yield=1.61 g. (78%). 1H NMR (dmso-d6): 10.5 (s, 1H), 9.14 (s, 1H), 6.71 (d, 1H, J=8.86 Hz), 6.34 (d, 1H, J=2.73 Hz), 6.26 (dd, 1H, J=8.83 and 2.62 Hz), 4.41 (s, 1H). 13C NMR (dmso-d6): 166.1, 153.2, 136.5, 128.5, 117.2, 109.8, 103.5, 67.5. ES-HRMS [M+H]+ 166.0500. Calcd for (C8H8NO3): 166.0478.

Provenance & Evidence