Reaktion #5803

Reaktionsgleichung

diethyl ether

t-butyl alcohol

(±)-cis-6-(cyanomethyl)-2,2-dimethyl-1,3-dioxane-4-acetic acid

dicyclohexylcarbodiimide

→

(±)-cis-1,1-dimethylethyl 6-(cyanomethyl)-2,2-dimethyl-1,3-dioxane-4-acetate

Lösungsmittel

dichloromethane

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturto slowly warm to room temperature over a 76.5-hour period
2. 2
   workup.STIRRINGstirring
3. 3
   workup.WAITcontinues five hours
4. 4
   Filtrationthe mixture filtered
5. 5
   WaschenThe precipitate is washed with diethyl ether
6. 6
   EinengenThe filtrate is concentrated to an oil
7. 7
   SonstigeThe crude product is chromatographed on silica gel eluting with 4:1 hexane
8. 8
   EinengenThe eluate is concentrated

Vorschrift

(±)-cis-6-(cyanomethyl)-2,2-dimethyl-1,3-dioxane-4-acetic acid (3.72 g, 17.44 mmol) is dissolved in 20 mL of dichloromethane, cooled to 0° C. and 0.2 g of 4-dimethylaminopyridine (DMAP) is added, followed by t-butyl alcohol and followed by 4.32 g of dicyclohexylcarbodiimide (DCC). This solution is allowed to slowly warm to room temperature over a 76.5-hour period. Thin layer chromotography (TLC) shows mainly product, and some slightly lower Rf by-products. The mixture is stirred one hour and 50 mL of dichloromethane is added and stirring continues five hours. An additional 100 mL of diethyl ether is added and the mixture filtered. The precipitate is washed with diethyl ether. The filtrate is concentrated to an oil. The crude product is chromatographed on silica gel eluting with 4:1 hexane:ethyl acetate. The eluate is concentrated to yield (±)-cis-1,1-dimethylethyl 6-(cyanomethyl)-2,2-dimethyl-1,3-dioxane-4-acetate.

Quelle