反应详情

A solution of 5c (157 mg, 0.53 mmol) in MeOH (4.40 mL) at room temperature was treated dropwise with 3 M HCl (1.40 mL, 4.21 mmol), then heated to reflux for one hour. Water (5 mL) was added and the solution was extracted with EtOAc (3×10 mL). Combined organic fractions were washed with saturated aqueous NaCl, dried (Na2SO4), filtered, and concentrated to afford 6c as a red amorphous solid (95 mg, 99%): 1H NMR (CDCl3, 500 MHz) δ 6.54 (d, J=8.7 Hz, 1H), 6.21 (d, J=8.7 Hz, 1H), 5.78 (s, 1H), 4.37-4.32 (m, 1H), 2.09 (s, 3H), 1.25 (d, J=6.1 Hz, 6H); 13C NMR (CDCl3, 125 MHz) δ 147.7, 144.9, 137.5, 110.8, 109.8, 104.0, 71.7, 21.3 (2C); IR (film) νmax 3526, 2974, 2924, 2853, 1717, 1607, 1475, 1238, 1113, 1067, 928, 887, 791 cm−1.

1. temperatureheated
2. temperatureto reflux for one hour
3. extractionthe solution was extracted with EtOAc (3×10 mL)
4. washCombined organic fractions were washed with saturated aqueous NaCl
5. dry with materialdried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated