Sodium Hydroxide → 3-Cyclopentyl-2-(4-methanesulfonyl-phenyl)-acrylic acid

Participants

Reaction Conditions

Reaction Steps

A solution of the isomeric mixture of 3-cyclopentyl-2-(4-meth-anesulfonyl-phenyl)-acrylic acid ethyl ester [65.02 g, 0.202 mol, (E):(Z)=1.63:1] in methanol (504 mL) was treated with a 1N aqueous sodium hydroxide solution (423 mL, 0.423 mol). The reaction mixture was stirred at 25° C. for 20 h, at which time, thin layer chromatography indicated the presence of starting material. The reaction mixture was then concentrated in vacuo to remove some of the methanol (300 mL). The resulting reaction mixture was heated under reflux for 1 h, at which time, thin layer indicated the absence of starting material. The reaction mixture was then concentrated in vacuo to remove methanol. The remaining aqueous layer was acidified to pH=1 with concentrated hydrochloric acid and then extracted with ethyl acetate (2×1 L). The combined organic layers were dried over magnesium sulfate, filtered, and concentrated in vacuo to afford 3-cyclopentyl-2-(4-methanesulfonyl-phenyl)-acrylic acid (62.58 g) as a cream solid consisting of a 16.2:1 mixture of (E):(Z) isomers. The cream solid was treated with ethyl acetate (200 mL), and the resulting slurry was heated to a boil. The resulting white solid surrounded by a light yellow liquid of ethyl acetate was allowed to cool to 25° C. The solid was filtered to afford pure (E)-3-cyclopentyl-2-(4-methanesulfonyl-phenyl)-acrylic acid (41.18 g, 69%) as a white solid: mp 200-202° C.; EL-HRMS m/e calcd for C15H18O4S (M+) 294.0926, found 294.0921.

Provenance & Evidence