反应详情

温度

-70 °C

t-Butyl lithium (1.7M in hexane) (29.23 ml, 49.7 mmol) was added dropwise to 3,4-dibromofuran (11.23 g, 49.7 mmol) in THF (120 ml) maintaining the temperature below -65° C. After 1 h at -70° C. dimethylaminoformamide (7.70 ml, 99.4 mmol) was added dropwise. After 2 h at -70° C. the solution was warmed to room temperature, acidified with 6N hydrochloric acid and the solution extracted with ethyl acetate. Drying (Na2SO4), evaporation to dryness under reduced pressure and purification by flash chromatography using hexane/dichloromethane (1:1) as eluent gave a mixture (3:1) of 3-bromofuran-4-carboxaldehyde and 3,4-dibromofuran-2-carboxaldehyde (4.36 g). This mixture (4.36 g) was treated with sodium borohydride (0.54 g, 14.25 mmol) in aqueous ethanol (4:1) (50ml) at 5° C. After 2 h at 5° C. the mixture was acidified with 6N hydrochloric acid and the solution extracted with ethyl acetate. Drying (Na2SO4), evaporation to dryness under reduced pressure and purification by flash chromatography using dichloromethane/hexane (4:1) as eluent gave the title compound (1.55 g, 18% ) as an amorphous yellow solid; δH (CDCl3) 1.74 (1H, br, s, OH), 4.54 (2H, s, CH2), 7.40-7.47 (2H, m, 2 and 5-H); δC (CDCl3) 55.4 (CH2), 100.7 (C-3), 125.4 (C-4), 141.1, 141.5; m/z 178 (M+, 97%), 176 (100%); (Found: M+, 175.9476. C5H5O2Br requires M, 175.9473).

1. temperaturemaintaining the temperature below -65° C
2. extractionthe solution extracted with ethyl acetate
3. customDrying
4. custom(Na2SO4), evaporation to dryness
5. customunder reduced pressure and purification by flash chromatography