Réaction #2645

Équation de réaction

chloroform

(-)-cis-4-tert-butyldimethylsilyloxy-2-cyclopentenol

chloroform

triethylamine

vinyl acetate

Cis-4-tert-butyldimethylsilyloxy-2-cyclopentenol

→

(-)-acetic acid 4-tert-butyldimethylsilyloxy-cyclopent-2-enyl ester

Rendement 51.1%

Solvants

tert-butyl methyl ether

Conditions de réaction

Traitement

1. 1
   FiltrationThe reaction is then filtered through diatomaceous earth
2. 2
   Concentrationthe filtrate is concentrated under vacuum
3. 3
   AutreThe products are separated by chromatography on silica gel (5% to 20% ethyl acetate/hexane)

Mode opératoire

Cis-4-tert-butyldimethylsilyloxy-2-cyclopentenol (10.0 g, 46.6 mmol, prepared in example 3a) is dissolved in tert-butyl methyl ether (60 mL, anhydrous). To the solution is added triethylamine (4.5 mL, 32.3 mmol), pancreatin (30 g, available from Sigma Chemical Company), and vinyl acetate (22 mL, 239 mmol). The reaction is allowed to stir for 7 hours at room temperature. The reaction is then filtered through diatomaceous earth and the filtrate is concentrated under vacuum. The products are separated by chromatography on silica gel (5% to 20% ethyl acetate/hexane) to provide (-)-acetic acid 4-tert-butyldimethylsilyloxy-cyclopent-2-enyl ester (B, 6.1 g, 51% yield, 99% ee), [α]D -0.2°, (c=0.52, chloroform) as a yellow oil and (-)-cis-4-tert-butyldimethylsilyloxy-2-cyclopentenol (A, 4.7 g, 47% yield, >99% ee), [α]D -18.6°, (c=1.01, chloroform) as a yellow oil.

Source