Reaction #501311

Reaction equation

ammonium chloride

methoxyallene

I2

3-bromobenzaldehyde ethylene acetal

→

3(2-propynyl)benzaldehyde ethylene acetal

Solvents

THF

THF

THF

Conditions

Workup

1. 1
   Temperaturebecomes warm
2. 2
   Temperaturewhen it is cooled to 15°
3. 3
   Temperatureis cooled to -20°
4. 4
   workup.ADDITIONThe above Grignard solution (under moisture excluding conditions) is then added to this solution during 5 minutes
5. 5
   Temperatureto warm to 20°
6. 6
   workup.STIRRINGwith stirring over 30 minutes
7. 7
   Extractionthe product is extracted with ether
8. 8
   WashThe ether layer is washed with water
9. 9
   Dryingdried (MgSO4)
10. 10
    workup.DISTILLATIONthe residue distilled in vacuo
11. 11
    OtherYield 4.3 g (75%) 89°-96° (0.03 m Hg)

Procedure

Dry Mg (0.74 g) under dry N2 in a flask is covered with THF (10 ml) and a crystal I2 added. 5 ml of a solution of 3-bromobenzaldehyde ethylene acetal (7.0 g) in THF (30 ml) is added and kept until it becomes warm, when it is cooled to 15°, and the remainder of the acetal solution added over 15 minutes, then stirred for an additional 1 hour. A mixture of methoxyallene (2.45 g), copper (1)chloride (0.30 g) and THF (30 ml) is cooled to -20°. The above Grignard solution (under moisture excluding conditions) is then added to this solution during 5 minutes, and allowed to warm to 20° with stirring over 30 minutes. Saturated aqueous ammonium chloride is added and the product is extracted with ether. The ether layer is washed with water, dried (MgSO4) and the residue distilled in vacuo. Yield 4.3 g (75%) 89°-96° (0.03 m Hg), nD20 1.5422.

Source