Water → (2R)-2-(tetrahydro-2H-pyran-2-yloxy)propyl 4-methylbenzenesulfonate

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Reaction Steps

A solution of 2-O-tetrahydropyrany-(R)-propane-1,2-diol(67.2 g, 0.42 mol) in pyridine (600 ml) was placed in a 2 l round-bottom flask with magnetic stirring rod and 500 ml dropping funnel with a side-tubing, protected by calcium chloride tube. 4-Dimethylaminopyridine (2 g) was added, the flask was placed in an ice-water cooling bath and a solution of p-toluenesulfonyl chloride (91 g, 0.477 mol) in pyridine (300 ml) was added over 1 hour under stirring. The mixture was stirred under ice-cooling for additional 3 hours and left to stand overnight in a refrigerator at 4° C. Water (20 ml) was then added to the mixture and, after standing for 1 hour, pyridine (approx. 300 ml) was distilled off in vacuo. The residue was diluted by ethyl acetate (2.5 l) and shaken with water (300 ml). After separation of the lower aqueous layer, the organic phase was washed with water (two 300 ml portions), evaporated in vacuo and the residue co-evaporated with toluene (four 250-ml-portions) in vacuo. The remaining amber oil was purified by chromatography over silica gel (eluting with chloroform) to afford 122 g (0.39 mol, 93%) of (R)-2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2 diol as a thick colorless oil, RF 0.60 (TLC, chloroform). This product was stored at +4° C. for several months without obvious decomposition. For C15H22OS (MW 314,4) calculated: C,57.30; H,7.05; S,10.20. Found: C,57.15; H,7.22; S,10.52.

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