Acetone → 2-Ethyl-1-hydroxy-4-phenylindene

A 200-ml three-necked round flask equipped with a stirring bar, a Dimroth condenser, a dropping funnel and a thermometer was charged with 0.85 g (22.6 mmol) of sodium borohydride and 28 ml of ethanol. To the mixture was dropwise added a solution containing 10.6 g (45.1 mmol) of the above-obtained 2-ethyl-4-phenyl-1-indanone dissolved in 20 ml of ethanol at room temperature under a nitrogen atmosphere. After the addition was completed, the temperature of was elevated to 50° C., and the reaction mixture was stirred for 3.5 hours. After the reaction was completed, the unreacted sodium borohydride was decomposed by acetone. Then, the reaction mixture was concentrated under reduced pressure, and then dissolved in 50 ml of water and extracted with 50 ml of ether. After the organic phase was separated, the aqueous phase was extracted with 50 ml of ether two times. The combined organic phase was washed with 100 ml of a saturated aqueous solution of sodium chloride, followed by drying over anhydrous Na2SO4. The solvent was evaporated under reduced pressure to obtain 10.67 g of the desired product as a pasty pale yellow liquid (mixture of two kinds of isomers) (yield; 99%).