反应详情

To a flask charged with dry, freshly ground magnesium turnings (1.1 g, 45 mmol) and iodine (25 mg, 0.1 mmol) in THF (50 mL) was added a solution of 1,4-dibromobenzene (10.6 g, 45.0 mmol) in THF (30 mL) slowly by dropping funnel over 30 min. The resulting mixture was stirred at rt for 1 hr. The resultant grey Grignard solution was cooled to −78° C. and to it was added a solution of 4-methylenecyclohexanone (3.3 g, 30 mmol) in THF (20 mL) slowly dropwise over 20 min. The reaction was stirred at −78° C. for 30 min before being allowed to stir and warm to rt for 3 h. The resulting reaction mixture was quenched with a saturated aqueous NH4Cl solution and extracted with methyl tert-butyl ether. The combined organic phases were washed with a saturated aqueous NaCl solution, dried over MgSO4, filtered and concentrated by rotary evaporation in vacuo to afford a crude yellow oil. Purification of the crude material by column chromatography (80 g silica gel, 0-50% EtOAc:Hept, monitor for 225 nm) afforded 2.94 g of a colorless oil that was used without further purification. ESI-MS m/z: not ionized [M+H]+, retention time 1.50 min (condition E).

1. additionTo a flask charged
2. customwith dry
3. customover 30 min
4. temperatureThe resultant grey Grignard solution was cooled to −78° C. and to it
5. stirringThe reaction was stirred at −78° C. for 30 min
6. stirringto stir
7. temperaturewarm to rt for 3 h
8. customThe resulting reaction mixture
9. customwas quenched with a saturated aqueous NH4Cl solution
10. extractionextracted with methyl tert-butyl ether
11. washThe combined organic phases were washed with a saturated aqueous NaCl solution
12. dry with materialdried over MgSO4
13. filtrationfiltered
14. concentrationconcentrated by rotary evaporation in vacuo
15. customto afford a crude yellow oil
16. customPurification of the crude material by column chromatography (80 g silica gel, 0-50% EtOAc:Hept, monitor for 225 nm)