Cyclopentadiene → 1,4-Methanonaphthalene

10 g of magnesium turnings which are covered with approximately 75 cm3 of anhydrous tetrahydrofuran are placed in a round flask fitted with a condenser, a thermometer, a nitrogen inlet, a dropping funnel, and protected from atmospheric moisture by a calcium chloride tube. 25 cm' of a solution, prepared beforehand, of 65 g of ortho-fluorobromobenzene and 26 g of cyclopentadiene in 200 cm3 of anhydrous tetrahydrofuran are then added. The formation of the organomagnesium compound is initiated by heating the reaction mixture locally with a hairdryer, and the solvent is then kept at boiling point by dropwise addition of the remaining solution. The whole addition is completed in approximately 1 hour. The mixture is then filtered at ambient temperature and the solution is concentrated under reduced pressure. The solution is taken up again in ether and the ether phase is washed with ammonium chloride, separated by gravity and dried over magnesium sulphate; the solvent is then removed by evaporation under vacuum. The residue is then distilled and benzonorbornadiene, whose boiling point is 82°-83° C. at a pressure of 16 millibars, is obtained in a yield of 40%.

1. customare placed in a round flask
2. customfitted with a condenser
3. customa thermometer, a nitrogen inlet, a dropping funnel, and protected from atmospheric moisture by a calcium chloride tube
4. custom25 cm' of a solution, prepared beforehand
5. temperatureby heating the reaction mixture locally with a hairdryer
6. additionby dropwise addition of the remaining solution
7. additionThe whole addition
8. filtrationThe mixture is then filtered at ambient temperature
9. concentrationthe solution is concentrated under reduced pressure
10. washthe ether phase is washed with ammonium chloride
11. customseparated by gravity
12. dry with materialdried over magnesium sulphate
13. customthe solvent is then removed by evaporation under vacuum
14. distillationThe residue is then distilled

ORD record

ord-c3489fa71a0048cf962c62e70f4ef6dc

Source dataset

uspto-grants-1988_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04783549