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温度

0 °C

The title compound was prepared according to Popio, V. V. et al. Synthesis (March 1991), pp 195-197. To a stirred suspension of NaH (1.2 g, 50 mmol) and ethyl propionate (5.73 mL. 50 mmol) in 20 mL THF at 20° C. was added EtOH (2 drops), acetophenone (3.0 g, 25 mmol) in 20 mL of THF, and dibenzo-18-crown-6 (150 mg, 0.4 mmol) in 20 mL of THF. Stirred for 30 min, then at reflux for 1 hr. Cooled (0° C.), then added 25 mL of 10% H2SO4 solution and the aqueous was extracted with Et2O. The organics were washed with H2O, aqueous Na2CO3, and brine. The solution was dried over Na2SO4 and concentrated. Purification by silica gel chromatography (1% to 10% EtOAc in hexanes) gave 4.0 g of Intermediate 16 as a thin oil. 1H NMR indicated an ˜10:1 mixture of tautomers favoring the enol form: 1H NMR (400 MHz, CDCl3, enol form) δ7.87 (m, 2H), 7.52-7.4 (m, 3H), 6.17 (s, 1H), 2.47 (q, 2H, J=7.5), 1.21 (t, 3H, J=7.5)

1. customThe title compound was prepared
2. customet al. Synthesis (March 1991), pp 195-197
3. temperatureat reflux for 1 hr
4. extractionthe aqueous was extracted with Et2O
5. washThe organics were washed with H2O, aqueous Na2CO3, and brine
6. dry with materialThe solution was dried over Na2SO4
7. concentrationconcentrated
8. customPurification by silica gel chromatography (1% to 10% EtOAc in hexanes)