Reaktion #1576117

Reaktionsgleichung

16-dehydropregnenolone

5,5-dibromobarbituric acid

hydrogen bromide

→

21-bromo-3β-hydroxypregna-5,16-dien-20-one

Ausbeute 104.4%

Lösungsmittel

tetrahydrofuran

methylene chloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturheat
2. 2
   Sonstigethe reaction
3. 3
   Temperaturat reflux for 1 hour
4. 4
   TemperaturCool slightly
5. 5
   Einengenconcentrate under vacuum
6. 6
   Sonstigeto produce a brown oily foam
7. 7
   Waschenrinse with 50% saturated sodium bicarbonate (2×200 mL), brine (125 mL)
8. 8
   Trocknendry over anhydrous magnesium sulfate
9. 9
   Filtrationfilter
10. 10
    Einengenconcentrate under vacuum

Vorschrift

Dissolve 16-dehydropregnenolone (5.00 g, 15.90 mmol) and 5,5-dibromobarbituric acid (4.55 g, 15.90 mmol) in tetrahydrofuran (60 mL). Add concentrated aqueous hydrogen bromide (100 μL of a 48% solution) to the stirring solution and heat the reaction at reflux for 1 hour. Cool slightly and then concentrate under vacuum to produce a brown oily foam. Dissolve the residue in methylene chloride (350 mL), rinse with 50% saturated sodium bicarbonate (2×200 mL), brine (125 mL), dry over anhydrous magnesium sulfate, filter and concentrate under vacuum to provide 21-bromo-3β-hydroxypregna-5,16-dien-20-one (6.53 g) as an orange-brown solid, slightly contaminated with starting material.

Quelle