(3aR,4R,5R,6aS)-4-formyl-2-oxohexahydro-2H-cyclopenta[b]furan-5-yl benzoate → HCID 57857028, compound

Participants

Reaction Conditions

Reaction Steps

A reactor equipped with a mechanical stirrer, under nitrogen, is charged with (3aR,4R,5R,6aS)-4-formyl-2-oxohexahydro-2H-cyclopenta[b]furan-5-yl benzoate (99.2 g, 0.362 mol) in DCM and lithium chloride (1 molar equivalent) dissolved in THF. Diethyl 2-(benzo[b]thiophen-2-yl)-2-oxoethylphosphonate (1 molar equivalent) is added neat and rinsed with DCM. Some lithium chloride precipitates from solution when the THF and DCM solutions are mixed. The mixture is stirred under nitrogen and cooled to −20° C. After adding the phosphonate and subsequent stirring and cooling, the lithium chloride dissolved. After stirring for 2.5 hours, triethylamine (1 molar equivalent) is added neat via addition funnel and the temperature is held at −5° C. and stirred at this temperature for 19 hours. The temperature is adjusted to 0° C. and treated with 5% aqueous citric acid and the layers are separated. The organic layer is dried over magnesium sulfate and filtered. The crude product is purified on silica gel, eluted with ethyl acetate-hexanes (1:1) to afford the title intermediate 4a.

Provenance & Evidence