237 mg of tosyl chloride and 350 mg of (S)-4-(2',5'-dimethoxy-3',4',6'-trimethylphenyl)-2-methyl-1,2-butanediol were dissolved in 1 ml of methylene chloride. 0.180 ml of pyridine was then added dropwise at 0° C. and the mixture was left to stand at 0° C. for 1 hour and then at room temperature for 16 hours. 1 g of ice and 0.3 ml of concentrated hydrochloric acid were thereupon added. The mixture was then extracted with methylene chloride and the extracts were dried and concentrated. There were obtained 511 mg (95%) of (S)-4-(2',5'-dimethoxy-3',4',6'-trimethylphenyl)-2-methyl-1-toluylsulphonyloxy-2-butanol. [α]D20 +1.2° (c=2.6% in chloroform).
