反应详情

Acetic anhydride (1 mL) was added dropwise to a solution of acid 8 (178 mg, 2.00 mmol) in pyridine (3 mL) at room temperature. After stirring for 48 hours, the mixture was poured into water (6 mL) and acidified to pH=2 by the dropwise addition of 6 M HCl. The suspension was extracted with EtOAc (2×10 mL), and the combined organic fractions were dried (Na2SO4), filtered and concentrated. The residue was purified by chromatography (5:1, hexanes:EtOAc) to afford acetate 9 (223 mg, 51%) as a white solid: 1H NMR (CDCl3, 400 MHz) δ 8.01-7.96 (m, 2H), 7.15 (dd, J=3.5, 8.2 Hz, 1H), 5.24 (tt, J=1.3, 7.2 Hz, 1H), 3.30 (d, J=7.2 Hz, 2H), 2.34 (s, 3H), 1.97 (s, 3H), 1.76 (s, 3H).

1. extractionThe suspension was extracted with EtOAc (2×10 mL)
2. dry with materialthe combined organic fractions were dried (Na2SO4)
3. filtrationfiltered
4. concentrationconcentrated
5. customThe residue was purified by chromatography (5:1, hexanes:EtOAc)