Reaction #88983

Reaction equation

H2SO4

[[(3aR,5S,6aR)-2,2-dimethyl-3a,5,6,6a-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl]-cyclopentyl-methyl] benzoate

compound 11b

[[(3aR,5S,6aR)-2,2-dimethyl-3a,5,6,6a-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl]-cyclopentyl-methyl] benzoate

acetic acid anhydride

NaHCO3

→

[cyclopentyl-[(2S,4R)-4,5-diacetoxytetrahydrofuran-2-yl]methyl] benzoate

Solvents

EtOAc

acetic acid

Conditions

Workup

1. 1
   OtherThe organic layer was separated
2. 2
   Washwashed with brine
3. 3
   Dryingdried over Na2SO4
4. 4
   Concentrationconcentrated in vacuo
5. 5
   OtherThe residue was purified by column chromatography on silica gel (eluting with 1:3 EtOAc in petroleum ether)

Procedure

To a solution of [[(3aR,5S,6aR)-2,2-dimethyl-3a,5,6,6a-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl]-cyclopentyl-methyl] benzoate (compound 11b, 800 mg, 2.3 mmol) in the mixture of acetic acid (2 mL) and acetic acid anhydride (2 mL) was added H2SO4 (0.2 mmol). After being stirred at room temperature for 24 hours, the solution was diluted by EtOAc (40 mL) and adjusted to pH 5.0 by addition of saturated NaHCO3 solution. The organic layer was separated, washed with brine, dried over Na2SO4 and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 1:3 EtOAc in petroleum ether) to afford 480 mg of [cyclopentyl-[(2S,4R)-4,5-diacetoxytetrahydrofuran-2-yl]methyl] benzoate (compound 11c).

Source