反应详情

The mixture of 4-hydroxyacetophenone (2.719 g, 20 mmol), paraformaldehyde (2.702 g, 90 mmol) and N-methylanilinium trifluoroacetate (6.603 g, 30 mmol) in 20 mL of anhydrous THF was refluxed for 3.5 h and cooled to room temperature. To the red solution was added 60 mL of diethyl ether and the mixture was vigorously stirred for 15 min. The resultant yellow solution was decanted and residual brown-red sticky mud was repeatedly extracted with 50 mL portions of diethyl ether until it turned into yellow solid. The combined organic extracts were washed with half saturated sodium bicarbonate solution (2×) and the aqueous wash was extracted with ether (2×). The combined organic layers were dried over anhydrous sodium sulfate prior to concentration. Flash chromatography on silica gel with 5:1 hexanes/ethyl acetate as the eluent afforded product 27 (1.21 g, 41%) as a pale yellow solid. 1H NMR (400 MHz, CDCl3): δ 5.89 (dd, J=1.8, 10.6 Hz, 1H), 5.91 (s, 1H), 6.43 (dd, J=1.6, 16.9 Hz, 1H), 6.92 (d, J=8.4 Hz, 2H), 7.17 (dd, J=10.6, 17.2 Hz, 1H), 7.93 (d, J=8.4 Hz, 2H).

1. temperaturewas refluxed for 3.5 h
2. customThe resultant yellow solution was decanted
3. extractionresidual brown-red sticky mud was repeatedly extracted with 50 mL portions of diethyl ether until it
4. washThe combined organic extracts were washed with half saturated sodium bicarbonate solution (2×)
5. washthe aqueous wash
6. extractionwas extracted with ether (2×)
7. dry with materialThe combined organic layers were dried over anhydrous sodium sulfate
8. concentrationto concentration