Hydrochloric Acid → Methyl 2-((1R,2R,3aS,9aS)-2,3,3a,4,9,9a-hexahydro-2-(tert-butyldimethylsilyoxy)-1-((S,E)-3-hydroxyoct-1-enyl)-1H-cyclopenta[b]naphthalen-5-yloxy)acetate

Participants

Reaction Steps

(1R,2R,3aS,9aS)-2,3,3a,4,9,9a-hexahydro-2-(tert-butyldimethylsilyoxy)-1-((S,E)-3-(tert-butyldimethylsilyoxy)oct-1-enyl)-1H-cyclopenta[b]naphthalen-5-ol (0.5 g, 0.89 mmol) in methyl bromoacetate (3 ml) was treated with 50% NaOH (1 g). The mixture was stirred at room temperature for 60 min. The reaction mixture was cooled to 10° C. and 3N HCl was added slowly until pH=7, and then the reaction was exacted with ethyl acetate. The organic layers were combined and dried over anhydrous magnesium sulfate. The solid was filtered off. The solvent was evaporated off under vacuum. The crude product was purified by chromatography on silica gel using a mixture of hexane and ethyl acetate as a gradient eluent. 0.2 g of Methyl 2-((1R,2R,3aS,9aS)-2,3,3a,4,9,9a-hexahydro-2-(tert-butyldimethylsilyoxy)-1-((S,E)-3-hydroxyoct-1-enyl)-1H-cyclopenta[b]naphthalen-5-yloxy)acetate was obtained. The product was then dissolved in THF (1.3 ml), acetic acid (3.9 ml) and distilled water (1.3 ml) for overnight at room temperature. The reaction mixture was poured to saturated sodium bicarbonate aqueous (1.0 ml) and stirred for 30 minutes. The reaction mixture was phase separated and the aqueous layer was extracted with 20 ml ethyl acetate. The organic layers were combined and dried over anhydrous magnesium sulfate. The solid was filtered off. The solvent was evaporated off under vacuum. The crude product was purified by chromatography on silica gel using a mixture of hexane and ethyl acetate as a gradient eluent. The titled compound was obtained in a crystalline form. (Yield: 58%)

Provenance & Evidence