反应详情

Magnesium (a) (12.5 g) was flame dried in a 250 ml 3-necked flask equipped with mechanical stirrer, reflux condenser, and addition funnel. The magnesium was covered with 52 ml of dry tetrahydrofuran (b) and reaction was initiated by the addition of ca. 0.5 ml of ethylene dibromide under a nitrogen atomosphere. To the stirred mixture was added 30.9 g of 2-bromopropene (c) dropwise at a rate which maintained reflux without external heating. After the addition, the Grignard solution was stirred until it had cooled to room temperature (0.5-1 hour) and then cooled to -15°. Then 27.35 g of trans-5-phenyl-4-pentenal (d) was added dropwise over 15 minutes. After the resultant green mixture was stirred at room temperature for 2 hours, 130 ml of a saturated solution of ammonium chloride was added followed by 200 ml of water. The layers were separated and the aqueous portion extracted with ether (3×200 ml). The organic layer were worked up in the usual manner to give after evaporation, the alcohol as an orange liquid (33 g). TLC; silica gel HF254 ; ethyl acetate/benzene 2:8 Rf 0.45.

1. customdried in a 250 ml 3-necked flask
2. customequipped with mechanical stirrer
3. temperaturereflux
4. additioncondenser, and addition funnel
5. customThe magnesium was covered with 52 ml of dry tetrahydrofuran (b) and reaction
6. temperaturemaintained
7. temperaturereflux without external heating
8. additionAfter the addition
9. temperaturecooled to -15°
10. stirringAfter the resultant green mixture was stirred at room temperature for 2 hours
11. customThe layers were separated
12. extractionthe aqueous portion extracted with ether (3×200 ml)
13. customto give
14. customafter evaporation