Réaction #55634

Équation de réaction

Diborane

3-methyl-4-(tetrahydropyran-2-yloxy)-1-butene

bromine

sodium methoxide

→

1-bromo-3-methyl-4-(tetrahydropyran-2-yloxy)-butane

Solvants

water

tetrahydrofuran

tetrahydrofuran

methanol

Conditions de réaction

Traitement

1. 1
   workup.ADDITIONAfter the addition
2. 2
   TempératureThe reaction mixture is cooled to 0°
3. 3
   workup.ADDITIONAfter the addition
4. 4
   Températureto warm to room temperature
5. 5
   workup.STIRRINGstirred for 30 minutes
6. 6
   Extractionextracted with petroleum ether (2×200 ml)
7. 7
   LavageThe organic layer is washed with 5% sodium bicarbonate (100 ml), water (2×100 ml)
8. 8
   Séchagedried (Na2SO4)
9. 9
   AutreThe solvent is removed in vacuo
10. 10
    Autreto give a colorless liquid
11. 11
    AutreThis crude product is purified by column chromatography in silica gel (500 g, 1% ether in petroleum ether)

Mode opératoire

Diborane in tetrahydrofuran (125 ml, 0.150 m) at 0° C. under nitrogen is added to a mixture of 3-methyl-4-(tetrahydropyran-2-yloxy)-1-butene (72 g, 0.423 m) and tetrahydrofuran (150 ml). After the addition is complete, the mixture is allowed to warm to room temperature and then stirred for 1 hour. The reaction mixture is cooled to 0° and bromine (24 ml, 0.43 mmole) and sodium methoxide (0.565 m) in methanol (300 ml) are added slowly simultaneously. After the addition is complete, the mixture is allowed to warm to room temperature and stirred for 30 minutes. The mixture is then treated with water (100 ml) and extracted with petroleum ether (2×200 ml). The organic layer is washed with 5% sodium bicarbonate (100 ml), water (2×100 ml) and dried (Na2SO4). The solvent is removed in vacuo to give a colorless liquid. This crude product is purified by column chromatography in silica gel (500 g, 1% ether in petroleum ether) to give 1-bromo-3-methyl-4-(tetrahydropyran-2-yloxy)-butane (71 g, 65%) as a colorless liquid.

Source