反应详情

A solution of 5a (910 mg, 3.37 mmol) in MeOH (28.0 mL) at room temperature was treated dropwise with 3 M HCl (9.00 mL, 26.9 mmol), then heated to reflux for one hour. Water (30 mL) was added and the solution was extracted with EtOAc (3×30 mL). Combined organic fractions were washed with saturated aqueous NaCl, dried (Na2SO4), filtered, and concentrated. The residue was purified via column chromatography (SiO2, 6:1 Hexane:EtOAc) to afford 6a as a red amorphous solid (509 mg, 98%): 1H NMR (Acetone-d6, 500 MHz) 7.68 (s, 1H), 7.24 (s, 1H), 6.60 (d, J=11 Hz, 1H), 6.29 (d, J=11 Hz, 1H), 3.74 (s, 3H), 2.09 (s, 3H); 13C NMR (CDCl3, 125 MHz) δ 144.7, 142.1, 139.7, 115.6, 110.2, 108.6, 55.6, 7.6; IR (film) νmax 3583, 2920, 2359, 1616, 1259, 1090, 1020, 798 cm−1.

1. temperatureheated
2. temperatureto reflux for one hour
3. extractionthe solution was extracted with EtOAc (3×30 mL)
4. washCombined organic fractions were washed with saturated aqueous NaCl
5. dry with materialdried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was purified via column chromatography (SiO2, 6:1 Hexane:EtOAc)