反応 #3186

反応方程式

3β-acetoxy-5-cholenic acid chloride

hydrochloric acid

2-bromopropane

isopropyl-magnesium bromide

magnesium

→

3β-acetoxy-24-oxo-5-cholestene

収率 70.0%

溶媒

benzene

benzene

ether

反応条件

後処理

1. 1
   workup.ADDITIONAfter the addition
2. 2
   workup.STIRRINGthe reaction mixture was stirred for thirty minutes
3. 3
   その他The ethereal solution was transferred to another flask
4. 4
   温度The resulting dark solution was refluxed gently for one hour
5. 5
   その他most of the ether was removed
6. 6
   workup.STIRRINGThe reaction mixture was stirred at room temperature for one hour
7. 7
   その他The organic layer was separated
8. 8
   抽出The aqueous layer was extracted with ether (3×300 ml)
9. 9
   洗浄The combined ethereal solution was washed with 10% HCl
10. 10
    洗浄washed with water
11. 11
    乾燥dried (MgSO4)
12. 12
    ろ過filtered
13. 13
    濃縮concentrated in vacuo

実験手順

To a mixture of magnesium (24 g, 1.00 mole) in dry ether (500 ml) was added dropwise 2-bromopropane (60 ml, 639 mmole) while stirring. After the addition was completed, the reaction mixture was stirred for thirty minutes. The ethereal solution was transferred to another flask. Then to the resulting isopropyl-magnesium bromide solution was added portionwise cadmium bromide (75 g, 276 mmole) at room temperature. The resulting dark solution was refluxed gently for one hour, followed by the addition of dry benzene (200 ml), then most of the ether was removed. To this mixture, 3β-acetoxy-5-cholenic acid chloride 331 (50 g, 115 mmole) in dry benzene (300 ml) was added dropwise. The reaction mixture was stirred at room temperature for one hour and then poured slowly into a crushed ice and 10% hydrochloric acid mixture. The organic layer was separated. The aqueous layer was extracted with ether (3×300 ml). The combined ethereal solution was washed with 10% HCl, washed with water, dried (MgSO4), filtered, and concentrated in vacuo to give crude product, 3β-acetoxy-24-oxo-5-cholestene 332 (35.6 g, 70% yield), which was used for the next reaction without further purification. 1H NMR (400 MHz, CDCl3) δ: 0.69 (3H, s, 18-CH3), 0.95 (3H, d, 21-CH3), 1.04 (3H, s, 19-CH3), 1.25 (6H, 2d, 26-CH3, 27-CH3), 2.04 (3H, s, --OCOCH3), 4.61 (1H, m, 3α-H), 5.38 (1H, m, 6-H).

出典