Reaktion #2645

Reaktionsgleichung

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

Ausbeute 51.1%

Lösungsmittel

tert-butyl methyl ether

Reaktionsbedingungen

Aufarbeitung

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

Vorschrift

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.

Quelle