3 g of 2-tosyloxymethyl-3,4-dihydro-2H-pyran and 1.91 g of p-chlorobenzyl alcohol were dissolved in 40 ml of diethyl ether, and 2-3 drops of phosphorus oxytrichloride were added to the resulting solution. The mixture was then allowed to react at room temperature for 1.5 days, after which 2 drops of triethylamine were added and the mixture was concentrated by evaporation under reduced pressure. The residue was subjected to column chromatography through silica gel, eluted with a 8:1 by volume mixture of hexane and ethyl acetate, to give 3.44 g of trans-6-(4-chlorobenzyloxy)-2-tosyloxymethyltetrahydropyran (having the lesser polarity), 0.59 g of cis-6-(4-chlorobenzyloxy)-2-tosyloxymethyltetrahydropyran (having the greater polarity) and 0.86 g of an approximately 1:1 cis/trans mixture.
