In 100ml round-bottomed flask, by 2-cyclopenta ethyl benzoylacetate (10.6g, 43.05mmol, 1.0eq), NaOH (2.6g, 64.5mmol) and Na2CO3(4.5g, 43mmol), is suspended in 50.0mLH2In O, it is warmed up to 80 DEG C and reacts 3 hours, obtain product phenylcyclopentyl ketone.Purify: reactant liquor is cooled to room temperature, extract 3 times with ethyl acetate 20mL;Organic phase saturated sodium-chloride washs, and merges organic phase and uses anhydrous MgSO4Being dried, then remove solvent under reduced pressure, obtain thick product, column chromatography purifies, and eluant, eluent is ethyl acetate: petroleum ether (1:10), obtains 6.54g target product, yield 87.2%.