Реакция #1886335

Уравнение реакции

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

Выход 77.1%

Растворители

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Условия реакции

Обработка

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

Методика

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.

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