Reaction #2655

Reaction equation

bicarbonate

p-toluenesulfonic acid

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

carbonate

→

title compound

Yield 75.0%

(-)-cis-4-acetoxy-cyclopent-2-enol

Yield 75.0%

Solvents

chloroform

ethanol

Conditions

Workup

1. 1
   Otherthe reaction at room temperature for 2 hours
2. 2
   Concentrationconcentrate under vacuum
3. 3
   OtherPurify the residue by chromatography (silica gel, 3 g, 1.5×3 cm column, 33% ethyl acetate/hexane, 80 mL)

Procedure

Dissolve (-)-acetic acid cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enyl ester (192 mg, 0.85 mmol, prepared in example 11) in ethanol (1.5 mL) and treat with p-toluenesulfonic acid (11.7 mg). Stir the reaction at room temperature for 2 hours. Add carbonate or bicarbonate to neutralize the reaction mixture and concentrate under vacuum. Purify the residue by chromatography (silica gel, 3 g, 1.5×3 cm column, 33% ethyl acetate/hexane, 80 mL), to provide the title compound (90 mg, 75% yield, 91% ee), [α]20 D =-66.1°, (c=0.63, chloroform).

Source