Reaktion #2646

Reaktionsgleichung

chloroform

(-)-cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol

chloroform

triethylamine

vinyl acetate

Cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol

→

(-)-acetic acid cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enyl ester

Ausbeute 45.0%

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 (10% to 20% ethyl acetate/hexane)

Vorschrift

Cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol (1.091 g, 5.92 mmol, prepared in example 6) is dissolved in tert-butyl methyl ether (8.6 mL, anhydrous). To the solution is added triethylamine (0.59 mL, 4.2 mmol), pancreatin (3.2 g, available from Sigma Chemical Company), and vinyl acetate (2.7 mL, 29 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 (10% to 20% ethyl acetate/hexane) to provide (-)-acetic acid cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enyl ester (B, 601 mg, 45% yield, 91% ee) [α]D =-19.8°,(c=1.00, chloroform) as a yellow oil and (-)-cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol (A, 560 mg, 50% yield, 94% ee), [α]D =-9.9°, (c=1.06, chloroform) as a yellow oil.

Quelle