Lithium Hydroxide → (E)-3-cyclopentyl-2-(3,4-dichloro-phenyl)-acrylic acid

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Reaction Conditions

Reaction Steps

A solution of the isomeric mixture of 3-cyclopentyl-2-(3,4-dichloro-phenyl)-acrylic acid methyl ester [821.1 mg, 2.74 mmol, (E):(Z)=4.5:1] in tetrahydrofuran (3.4 mL) was treated with a 0.8M aqueous lithium hydroxide solution (3.4 mL, 2.74 mmol). The reaction mixture was stirred at 25° C. for 17 h and then heated under reflux for 4 h. The reaction mixture was allowed to cool to 25° C. and then concentrated in vacuo to remove tetrahydrofuran. The remaining aqueous layer was acidified to pH=2 with a 10% aqueous hydrochloric acid solution and then extracted with ethyl acetate (2×150 mL). The combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 70-230 mesh, 1/1 hexanes/ethyl acetate) afforded pure (E)-3-cyclopentyl-2-(3,4-dichloro-phenyl)-acrylic acid (205.4 mg, 26%) as a white solid: mp 119-120° C.; EI-HRMS m/e calcd for C14H14Cl2O2 (M+) 284.0371, found 284.0370.

Provenance & Evidence