Reaktion #51877

Reaktionsgleichung

cyclohexane-1,4-dione monoethylene ketal

n-butyl lithium

diisopropylamine

ammonium chloride

3-(benzyloxy)-2-cyclohexen-1-one

→

title compound

Ausbeute 88.2%

(±)-3-(Benzyloxy)-6-(8-hydroxy-1,4-dioxaspiro[4.5]dec-8-yl)-2-cyclohexen-1-one

Ausbeute 88.2%

Lösungsmittel

dichloromethane

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeTo a flask equipped with magnetic stirrer
2. 2
   workup.STIRRINGThe solution was stirred for 1 hr
3. 3
   workup.STIRRINGThe solution was stirred for 2 hr at −78° C.
4. 4
   Temperaturto warm slowly to room temperature over 1 hr
5. 5
   workup.STIRRINGthe mixture stirred until no solids
6. 6
   SonstigeThe layers were separated
7. 7
   Extraktionthe aqueous phase extracted with dichloromethane (2×100 ml)
8. 8
   WaschenThe combined organic layers were washed with brine (50 ml)
9. 9
   Trocknendried over magnesium sulfate
10. 10
    Einengenconcentrated in vacuo

Vorschrift

To a flask equipped with magnetic stirrer was added tetrahydrofuran (600 ml) and diisopropylamine (38.1 ml, 272 mmol). The stirred solution was cooled to −78° C. and n-butyl lithium (113.4 ml, 272 mmol, 2.4 M in hexanes) was added dropwise via syringe. The resulting yellow solution was stirred for 35 min at −78° C., then 3-(benzyloxy)-2-cyclohexen-1-one (50.0 g, 248 mmol) was added as a solution in tetrahydrofuran (100 ml). The solution was stirred for 1 hr prior to the addition of cyclohexane-1,4-dione monoethylene ketal (38.7 g, 248 mmol) as a solution in anhydrous tetrahydrofuran (100 ml). The solution was stirred for 2 hr at −78° C., then allowed to warm slowly to room temperature over 1 hr. Saturated aqueous ammonium chloride (80 ml) was added, followed by dichloromethane (700 ml) and the mixture stirred until no solids remained. The layers were separated and the aqueous phase extracted with dichloromethane (2×100 ml). The combined organic layers were washed with brine (50 ml), dried over magnesium sulfate, then concentrated in vacuo. Trituration of the resulting solid with methanol afforded the title compound (78.4 g, 88%). m/z (ES+) 359 (M+H+).

Quelle