Reaktion #446227

Reaktionsgleichung

1-(3-bromobenzyl)imidazole

2,2-dimethyl-4-pentenaldehyde

n-butyllithium hexane

diisopropyl ether hexane

diisopropylamine

→

1-(3-bromophenyl)-3,3-dimethyl-1-(1-imidazolyl)-5-hexen-2-ol

Ausbeute 74.4%

lithium diisopropylamide

Lösungsmittel

THF

THF

water

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe mixture was stirred at about -70° C. for a further 20 minutes
2. 2
   workup.ADDITIONwere subsequently added dropwise at 0° C.-5° C.
3. 3
   workup.STIRRINGthe mixture was stirred for 1 hour with ice cooling
4. 4
   SonstigeAfter separating the phases
5. 5
   Extraktionthe aqueous solution was extracted repeatedly with ether
6. 6
   SonstigeThe extract residue (7.3 g) was chromatographed by elution with CH2Cl2 and CH2Cl2 /C2H5OH
7. 7
   Temperaturan increase in C2H5OH content (to a maximum of 2% by volume) on a silica gel S/CH2Cl2 column (φ 2.8 cm, height 48 cm)
8. 8
   WaschenAfter elution of 2.0 g preliminary fractions, 5.2 g of product
9. 9
   Waschenwere eluted in which the compound
10. 10
    Einengendesired was greatly concentrated

Vorschrift

A solution of lithium diisopropylamide was prepared in 40 ml of absolute tetrahydrofuran (THF) at -30° C. starting from 2.06 g (20.4 mmol) of diisopropylamine and 13.4 ml of 1.5 molar n-butyllithium/hexane solution (20 mmol). A solution of 4.75 g (20 mmol) of 1-(3-bromobenzyl)imidazole in 25 ml of absolute THF was added dropwise to this solution at -70° C. to -78° C., the mixture was stirred at about -70° C. for a further 30 minutes, a solution of 3.22 g of 70% purity (20 mmol) 2,2-dimethyl-4-pentenaldehyde in 30 ml of absolute THF was subsequently added dropwise at about -70° C., and the mixture was stirred at about -70° C. for a further 20 minutes and allowed to warm to room temperature over about 2.5 hours 300 ml of water were subsequently added dropwise at 0° C.-5° C., and the mixture was stirred for 1 hour with ice cooling. After separating the phases, the aqueous solution was extracted repeatedly with ether. The combined organic solutions were further worked up as described in Example 1. The extract residue (7.3 g) was chromatographed by elution with CH2Cl2 and CH2Cl2 /C2H5OH mixtures with an increase in C2H5OH content (to a maximum of 2% by volume) on a silica gel S/CH2Cl2 column (φ 2.8 cm, height 48 cm). After elution of 2.0 g preliminary fractions, 5.2 g of product were eluted in which the compound desired was greatly concentrated. From these 5.2 g, 3.05 g (φ 43.6% yield) of pure 1-(3-bromophenyl)-3,3-dimethyl-1-(1-imidazolyl)-5-hexen-2-ol of melting point 126° C. were obtained by crystallization from diisopropyl ether/hexane 2:1.

Quelle