21.6 g (48.7 mmol) of (4-carboxybutyl)triphenylphosphonium bromide are dried under vacuum for 1 h by heating to 130° C., and then brought to room temperature and dissolved in 300 ml of anhydrous THF. 10.9 g (97 mmol) of potassium tert-butoxide in 100 ml of THF are then slowly added and then the orange-red mixture is stirred for 15 minutes. A solution of 6.3 g (32.5 mmol) of 1-(3-methoxymethoxyphenyl)-1-ethanone in 50 ml of THF is then added dropwise and the reaction medium is stirred for 15 hours. After treating with a saturated ammonium chloride solution and extracting with ethyl acetate and then drying and evaporating the solvants of the organic phase, the residue is then dissolved in 50 ml of ethanol and then 1 ml of sulphuric acid is added. The reaction medium is heated to reflux temperature and stirred for 2 hours. After treating with water, the medium is extracted with ethyl acetate and then the organic phases are combined, dried and concentrated under reduced pressure. The residue is purified by chromatography on a silica column (eluent heptane 80-ethyl acetate 20) in order to obtain 1 g (12%) of ethyl (Z)-6-(3-hydroxyphenyl)hept-5-enoate and 1.3 g (16%) of ethyl (E)-6-(3-hydroxyphenyl)hept-5-enoate.
