(Diethylamino)sulfur trifluoride → (3S,4S)-1-benzyloxycarbonyl-3-bromomethyl-4-fluoropyrrolidine

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Reaction Steps

Process A: (3S,4R)-1-Benzyloxycarbonyl-3-bromomethyl-4-hydroxypyrrolidine (2.70 g) was dissolved in dichloromethane (60 mL). While the solution was chilled in an ice water bath, diethylaminosulfur trifluoride (2.30 mL) was added dropwise and the mixture was stirred at room temperature for 20 hours. Following addition of a saturated aqueous solution of sodium bicarbonate (30 mL) in an ice water bath, the dichloromethane layer was separated. The dichloromethane layer was washed sequentially with a saturated aqueous solution of sodium bicarbonate (30 mL) and saturated brine (30 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluant: hexane: ethyl acetate=2:1) to give (3S,4S)-1-benzyloxycarbonyl-3-bromomethyl-4-fluoropyrrolidine as a yellow-brown tar (2.20 g).

Provenance & Evidence