反应详情

温度

60 °C

In 35 mL of dry acetonitrile under nitrogen atmosphere was added 7.3 g (27.9 mmole) of triphenylphosphine. To the solution was added dropwise over 15 minutes 4.31 g of bromine (27.0 mmole) while cooling the reaction mixture to maintain the temperature between 0°-10° C. The solution was allowed to warm to room temperature (about 22°-25° C.) and 5.0 g (27.9 mmole) of p-nitrocinnamyl alcohol (Pfaultz & Bauer Chemical Co.) was added as a slurry in 50 mL of acetonitrile which caused an exothermic reaction, temperature about 45° C. The resulting dark red solution was heated for one hour at 60° C. with stirring and then poured into 500 mL of ether. Triphenylphosphine oxide precipitated from the solution after standing overnight (about 16 hours). The solution was filtered and 15 g of flash silica gel was added to the solution, followed by solvent removal. The resulting powder matrix was applied to a 3 in.×8 in. (7.6 cm×20.3 cm) flash column and the desired product was eluted with hexane, followed by 20% ethyl acetate in hexane to yield 5.8 g (23.9 mmole) of the desired pure trans product in 86% yield (MP=75°-76° C., Rf =0.81, 60:40 ethyl acetate:n-hexane) and was further characterized by:

1. temperaturewhile cooling the reaction mixture
2. temperatureto maintain the temperature between 0°-10° C
3. customan exothermic reaction, temperature about 45° C
4. customTriphenylphosphine oxide precipitated from the solution
5. custom(about 16 hours)
6. filtrationThe solution was filtered
7. addition15 g of flash silica gel was added to the solution
8. customfollowed by solvent removal
9. wash(7.6 cm×20.3 cm) flash column and the desired product was eluted with hexane
10. customto yield 5.8 g (23.9 mmole) of the desired pure trans product in 86% yield (MP=75°-76° C., Rf =0.81, 60:40 ethyl acetate:n-hexane)