Reacción #2146735

Ecuación de reacción

ethyl bromide

magnesium

(5Z)-3-methylnon-5-en-1-ol

2-methylbut-3-yn-2-ol

→

(9Z)-2,7-dimethyltridec-9-en-3-yne-2,5-diol

Rendimiento 77.1%

Disolventes

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturaby occasional heating with a heat gun
2. 2
   Temperaturaunder reflux
3. 3
   Temperaturato cool down to room temp.
4. 4
   workup.STIRRINGwith stirring
5. 5
   TemperaturaThe reaction mixture was then again refluxed for 3 h
6. 6
   Otrothe heating bath removed
7. 7
   workup.STIRRINGwith stirring over a period of 30 min
8. 8
   TemperaturaThe reaction mixture was refluxed
9. 9
   workup.STIRRINGwith stirring overnight
10. 10
    Temperaturato cool to room temp.
11. 11
    Otroquenched
12. 12
    workup.ADDITIONby pouring into 100 mL of an aqueous satd
13. 13
    OtroThe organic layer was separated
14. 14
    Extracciónthe aqueous one extracted three times with 500 mL of ether each
15. 15
    SecadoThe combined organic extracts were dried with sodium sulphate
16. 16
    Concentraciónconcentrated to dryness in a rotary evaporator
17. 17
    OtroThe resulting residue (10.8 g) was purified by flash chromatography (200 g of silica gel, pentane/ether, 1:1, Rf=0.22)

Procedimiento

A solution of 10.4 g (95.6 mmol) of ethyl bromide in 40 mL of dry tetrahydrofuran was added dropwise over a period of 30 min to a vigorously stirred suspension of 2.32 g (95.6 mmol) of magnesium turnings in 15 mL of dry tetrahydrofuran, with the reaction being initiated by occasional heating with a heat gun. After stirring the reaction mixture for 90 min under reflux, it was allowed to cool down to room temp., and a solution of 3.54 g (42.2 mmol) of 2-methylbut-3-yn-2-ol in 40 mL of dry tetrahydrofuran was added dropwise with stirring. The reaction mixture was then again refluxed for 3 h, the heating bath removed and a solution of 6.50 g (42.2 mmol) of (5Z)-3-methylnon-5-en-1-ol in 40 mL of dry tetrahydrofuran added at room temp. with stirring over a period of 30 min. The reaction mixture was refluxed with stirring overnight, allowed to cool to room temp., and quenched by pouring into 100 mL of an aqueous satd. NH4Cl solution. The organic layer was separated, and the aqueous one extracted three times with 500 mL of ether each. The combined organic extracts were dried with sodium sulphate, and concentrated to dryness in a rotary evaporator. The resulting residue (10.8 g) was purified by flash chromatography (200 g of silica gel, pentane/ether, 1:1, Rf=0.22) to furnish 7.76 g (77%) of (9Z)-2,7-dimethyltridec-9-en-3-yne-2,5-diol as a colourless oil.

Fuente