Lithium Hydroxide → Rac-trans-cyclopentane-1,2-dicarboxylic acid monoethyl ester

To a solution of rac-trans-cyclopentane-1,2-dicarboxylic acid diethyl ester (393 mg, 1.84 mmol) was added a solution of lithium hydroxide (75.5 mg, 1.8 mmol) in water (7 mL). The reaction mixture was stirred at room temperature for 30 minutes and then heated to 55° C. for 1 hr. The reaction mixture was cooled and evaporated under reduced pressure. The residue was dissolved in 25 mL water and washed with diethyl ether (2×5 mL). The pH of the aqueous layer was adjusted to pH 5 with 1N hydrochloric acid and extracted with methylene chloride (2×5 mL) and ethyl acetate (5 mL). The combined organic layers were dried over magnesium sulfate, filtered and evaporated to dryness under vacuum to give rac-trans-cyclopentane-1,2-dicarboxylic acid monoethyl ester (95 mg) that was used without further purification.