反应详情

To a solution of spiro[3,1-benzoxazine-4,1′-cyclobutan]-2(1H)-one (0.36 g, 1.9 mmol) and potassium acetate (0.56 g, 5.7 mmol) in acetic acid was added a solution of bromine (0.09 mL, 1.95 mmol) in acetic acid (2 mL) at room temperature. Upon completion by TLC of the reaction, the acetic acid was removed. The residue was treated with saturated sodium bicarbonate (100 mL) and the product extracted with ethyl acetate (50 mL). The organics were dried over magnesium sulfate and concentrated. Trituration of residue with ether gave 6-bromospiro[3,1-benzoxazine-4,1′-cyclobutan]-2(1H)-one (0.27 g, 52%) as a white solid. 1H NMR (DMSO-d6): δ 10.37 (s, 1H), 7.65 (d, 1H, J=2.1 Hz), 7.47 (dd, 1H, J=8.5, 2.2 Hz), 6.86 (d, 1H, J=8.5 Hz), 2.52–2.47 (m, 2H), 2.04–1.98 (m, 2H), 1.87–1.80 (m, 2H). MS (ESI) m/z 268/270 ([M+H]+); MS (ESI) m/z 266/268 ([M−H]−).

1. customUpon completion by TLC of the reaction
2. customthe acetic acid was removed
3. additionThe residue was treated with saturated sodium bicarbonate (100 mL)
4. extractionthe product extracted with ethyl acetate (50 mL)
5. dry with materialThe organics were dried over magnesium sulfate
6. concentrationconcentrated