17.5 g of 6-acetoxy-2-(4-aminophenoxymethyl)-2,5,7,8-tetramethylchroman were dissolved in a mixture of 130 ml of acetone and 30 ml of water, and 13 ml of concentrated hydrochloric acid, followed by 4.3 g of sodium nitrite dissolved in 8.5 ml of water, were added dropwise, with ice-cooling, to the product. 37.3 ml of ethyl acrylate were added dropwise, and then 680 mg of cuprous oxide were added gradually to the product, whilst keeping its temperature at 40°-43° C. Generation of nitrogen terminated after about 30 minutes. Benzene was then added to the reaction mixture (which consisted of 2 layers) to extract the organic layer. The benzene extract was washed with a saturated aqueous solution of sodium chloride and dried over anhydrous sodium sulfate. The solvent was then distilled off from the extract. The dark brownish oil thus obtained was subjected to silica gel column chromatography, eluted with a 1:1 by volume mixture of benzene and cyclohexane and then the proportion of benzene was progressively increased until it was eluted with benzene alone. Ethyl 3-[4-(6-acetoxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)phenyl]-2-chloropropionate was obtained from the fractions eluted with a 2:1 by volume mixture of benzene and cyclohexane and with benzene alone. Rf value on thin layer chromatography: 0.39 [silica gel; developing solvent:benzene:ethyl acetate=20:1 by volume].
