Reacción #2645

Ecuación de reacción

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

Rendimiento 51.1%

Disolventes

tert-butyl methyl ether

Condiciones de reacción

Tratamiento posterior

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

Procedimiento

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.

Fuente