A solution of ((1S,2S,3R,4R)-2-(3-(benzyloxy)benzyl)-4-(tert-butyldimethysilyoxy)-3-((S,E)-3-(tert-butyldimethylsilyoxy)oct-1-enyl)cyclopentyl)methanol (50 g, 0.075 mol) in dry CH2Cl2 (500 ml) was cooled to 0° C. under nitrogen and treated with triethylamine (31.3 ml, 0.225 mol), then with methanesulfonyl chloride (11.6 ml, 0.15 mol). The mixture was poured to saturated sodium bicarbonate aqueous and stirred for 30 minutes. The reaction mixture was phase separated and the aqueous layer was extracted with 500 ml ethyl acetate. The organic layers were combined and dried over anhydrous magnesium sulfate. The solid was filtered off. The solvent was evaporated off under vacuum. The crude product was purified by chromatography on silica gel using a mixture of hexane and ethyl acetate as a gradient eluent. Yield: 81%.
