0.48 g of ethyl 3-[4-(6-acetoxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)phenyl]-2-chloropropionate was dissolved in a mixture of 3 ml of absolute ethanol and 2 ml of dry tetrahydrofuran. An ethanolic solution of sodium ethoxide (prepared by dissolving 49.0 mg sodium in 2 ml of absolute ethanol) was added dropwise, under a nitrogen stream at 10°-13° C., to the resulting solution. The mixture was then reacted for 21 hours at 0°-5° C., after which 0.22 g of concentrated hydrochloric acid dissolved in 99.5% ethanol was added dropwise, with ice-cooling. The solvent was then distilled off from the reaction mixture under reduced pressure; the separated light reddish oil was extracted with chloroform; and the extract was washed with water and then dried over anhydrous sodium sulfate. The crude product obtained by distilling the chloroform off from the extract under reduced pressure was subjected to silica gel column chromatography, and the desired ethyl 2-chloro-3-[4-(6-hydroxy-2,5,7,8-tetramethyl-chroman-2-ylmethoxy)phenyl]propionate was obtained from the fractions eluted with benzene. Rf value on thin layer chromatography: 0.60 [silica gel; developing solvent; benzene:ethyl acetate=10:1 by volume].
