0.594 ml of titanium tetraisopropoxide is dissolved in 10 ml of dry methylene chloride. Thereupon, 524 ml of dibutyl D-tartrate are added dropwise at -20° C. and the mixture is left to stand at -20° C. for 10 minutes. 197 mg of 4-(2',5'-dimethoxy-3',4',6'-trimethylphenyl)-2-methyl-2-butenol are then added and subsequently 180 mg of tert.butyl hydroperoxide (80%) are added dropwise (as a solution in 0.5 ml of methylene chloride). The thus-obtained yellow solution is left to stand at -20° C. for 4 to 5 days, then treated with 5 ml of 1N sodium hydroxide solution, left to warm to room temperature and stirred for 1 hour. The phases are then separated, and the aqueous phase is washed twice with methylene chloride. The combined organic phases are subsequently dried over anhydrous sodium sulphate and concentrated. The thus-obtained colourless oil is dissolved in 20 ml of diethyl ether and stirred with 5 ml of 1N sodium hydroxide solution for 1 hour. The phases are again separated, the aqueous phase is washed twice with diethyl ether and the organic phases are dried over anhydrous sodium sulphate and concentrated. There are obtained 188 mg (98%) of (2R,3R)-4-(2',5'-dimethoxy-3',4',6'-trimethylphenyl)-2,3-epoxy-2-methylbutanol, [α]D20 +18.2° (c=2% in CHCl3).
