(3aR,4R,5R,6aS)-5-[tert-butyl(dimethyl)silyl]oxy-2-oxo-3,3a,4,5,6,6a-hexahydrocyclopenta[b]furan-4-carbaldehyde

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: n-heptylphosphonium bromide (3.185 g, 7.22 mmol) was dried under vacuum for 3 days and was then taken into dry THF (22 mL). Potassium tert-butoxide (7.2 mL, 7.2 mmol, 1 M/THF) was added and the resulting red-orange solution was stirred for 45 min. at room temperature. A solution of (3aR,4R,5R,6aS)-5-(tert-butyldimethylsilyloxy)-2-oxohexahydro-2H-cyclopenta[b]furan-4-carbaldehyde (5-1, 502 mg, 1.78 mmol, Cayman) in 7 mL THF was added by cannula, rinsing with 3 mL THF. After 1.5 h, the reaction was quenched by addition of saturated NH4Cl solution. The resulting mixture was extracted with ethyl acetate (3×) and the combined ethyl acetate solution was dried (Na2SO4), filtered and evaporated. Purification of the residue by flash chromatography on silica gel (Isco Combiflash unit) gave the title compound (595 mg, 91%). rinsing with 3 mL THF After 1.5 h the reaction was quenched by addition of saturated NH4Cl solution The resulting mixture was extracted with ethyl acetate (3×) the combined ethyl acetate solution was dried (Na2SO4) filtered evaporated Purification of the residue by flash chromatography on silica gel (Isco Combiflash unit)