Boron tribromide → 8-Hydroxy-2-methyl-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazine-6-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

In a 20 mL scintillation vial was added 8-methoxy-2-methyl-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazine-6-carbaldehyde 17 (111 mg, 0.502 mmol) and boron tribromide (2.0 mL, 2.000 mmol) in DCM (2.5 mL) and stirred at −10° C. for 1 h then slowly warmed to 23° C. and stirred overnight. The reaction was quenched with MeOH, taken up in EtOAc, washed with water and brine, dried over MgSO4, and concentrated in vacuo to give the title compound as a tan solid (100 mg, 0.483 mmol, 96% yield). 1H NMR (400 MHz, DMSO-d6) δ ppm 1.45 (d, J=6.82 Hz, 3H) 4.75 (q, J=6.82 Hz, 1H) 6.92 (d, J=2.02 Hz, 1H) 7.03 (d, J=1.77 Hz, 1H) 9.74 (s, 1H) 9.98 (br. s., 1H) 10.85 (s, 1H). ESI-MS: m/z 208.0 (M+H)+.

Provenance & Evidence