Hydrochloric Acid → (2S,4R)-1-allyloxycarbonyl-2-(2-fluoroethyloxymethyl)-4-methylsulfonyloxypyrrolidine

Participants

Reaction Steps

A solution of (2S,4R)-1-benzyloxycarbonyl-2-(2-fluoroethyloxymethyl)-4-methanesulfonyloxypyrrolidine (8.37 g) in a mixture of concentrated hydrochloric acid (4.3 ml) and methanol (86 ml) was hydrogenated under atmospheric pressure of hydrogen at ambient temperature for 3 hours in the presence of 10% palladium on carbon (0.86 g). The catalyst was filtered off and the filtrate was concentrated under reduced pressure to give a syrup. The syrup was dissolved in a mixture of water (50 ml) and tetrahydrofuran (50 ml). To the solution was dropwise added a solution of allyl chloroformate (2.87 ml) in tetrahydrofuran (5 ml) under ice-cooling with stirring, while keeping the pH between 8 and 9 with 4N aqueous sodium hydroxide. The mixture was stirred at the same condition for one hour, extracted with ethyl acetate (100 ml), washed in turn with water (100 ml) and brine (100 ml), dried over magnesium sulfate, and concentrated under reduced pressure to give a syrup. The syrup was subjected to a column chromatography on silica gel (75 g) and eluted with a mixture of methanol and chloroform (1:99 V/V) to give (2S,4R)-1-allyloxycarbonyl-2-(2-fluoroethyloxymethyl)-4-methanesulfonyloxypyrrolidine (6.50 g).

Provenance & Evidence