(5-Carboxypentyl)triphenylphosphanium bromide → 6-(4,6-Di-t-butyl-5-hydroxy-2-methyl-2,3-dihydrobenzofuran-2-yl)-5-hexenoic acid

Participants

Reaction Steps

Under a nitrogen atmosphere, a solution of 0.92 g of potassium t-butoxide in 10 ml of THF was added dropwise to a suspension of 0.46 g of 5-carboxypentyltriphenylphosphonium bromide in 5 ml of THF at 0° C., and the mixture was stirred for 30 minutes. To the reaction solution was added dropwise a solution of 4,6-di-t-butyl-2-formyl-2-methyl-5-trimethylsilyloxy-2,3-dihydrobenzofuran synthesized in Example 72-2) in 10 ml of THF, and the mixture was stirred overnight while slowly warming to room temperature. The reaction solution was extracted with water and diethyl ether, and the combined aqueous layers were acidified with concentrated hydrochloric acid and extracted with diethyl ether. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was purified by silica gel column chromatography eluting with n-hexane containing 50% ethyl acetate to give 0.22 g of 6-(4,6-di-t-butyl-5-hydroxy-2-methyl-2,3-dihydrobenzofuran-2-yl)-5-hexenoic acid as a colorless viscous liquid (yield 43%).

Provenance & Evidence