11.76 g (0.28 mole) of lithium aluminum hydride were suspended in 500 ml of anhydrous tetrahydrofuran, and a solution of 69.06 g (0.28 mole) of methyl 3-(3,4-dichlorophenyl)-3-butenoate [prepared as described in step (a) above] in 500 ml of anhydrous tetrahydrofuran was slowly added dropwise under a nitrogen atmosphere at 0° C. over a period of 15 minutes. The reaction mixture was then stirred at the same temperature for 30 minutes, after which 500 ml of water and 500 ml of a 10% w/v aqueous solution of sodium hydroxide were slowly added. The mixture was then stirred at room temperature for 1 hour. It was then filtered through a Celite (trade mark) filter aid, and the filtrate was extracted three times, each time with 500 ml of ethyl acetate. The combined organic extracts were then dried over anhydrous magnesium sulfate. The solvent was removed from the extract by distillation under reduced pressure, and the resulting residue was dried under reduced pressure. The residue was then dissolved in 250 ml of anhydrous dimethylformamide, and then 47.12 ml (0.34 mole) of triethylamine, 6.88 g (0.06 mole) of 4-dimethylaminopyridine and 50.96 g (0.34 mole) of t-butyldimethylsilyl chloride were added, in that order, whilst ice-cooling. The mixture was then stirred, whilst ice-cooling, for 2 hours. At the end of this time, 1 liter of ethyl acetate was added to the reaction mixture, and the mixture was washed, in turn, with ice-cooled 10% w/v aqueous hydrochloric acid and with a saturated aqueous solution of sodium chloride. It was then dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure, and the resulting residue was purified by silica gel flash column chromatography, using a gradient elution method, with mixtures of hexane and ethyl acetate ranging from 50:1 to 20:1 by volume as the eluent, to obtain 43.52 g (yield 47%) of the title compound as a colorless oil.
