To a mixture of diol 3 (29.2 mmol, 6.13 g), DMAP (0.82 mmol, 100 mg) and triethylamine (116.7 mmol, 16.2 mL, 11.8 g) in anhydrous CH2Cl2 (60 mL) was added tosyl chloride (37.9 mmol, 7.23 g) at 0° C. The reaction mixture was allowed to warm to room temperature and stirring was continued overnight. The mixture was then diluted with CH2Cl2 (100 mL) and was then washed with a saturated aqueous solution of NaHCO3, dried over Na2SO4, and concentrated under reduced pressure. The residue was chromatographed on a silica gel using hexane/EtOAc (7:3) as an eluent to give the oily tosylate 4 (10.2 g, 97%).
