Benzaldehyde → (3S,4S)-3-benzylaminomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine

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Reaction Steps

(3S,4S)-3-Aminomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine (1.10 g) was dissolved in methanol (13 mL). To this solution, molecular sieve 4A (440 mg) and then benzaldehyde (0.44 mL) were added. The mixture was stirred at room temperature for 1 hour, followed by addition of a borane/pyridine complex (0.44 mL) and further stirring at room temperature for 3.5 hours. Subsequently, 6 mol/L hydrochloric acid (7.3 mL) was added and the mixture was stirred at room temperature for 1 hour. A 30% aqueous solution of sodium hydroxide was then added to make the mixture basic. The mixture was extracted with diethyl ether (2×100 mL). The diethyl ether layers were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluant: hexane: ethyl acetate=4:1->1:1) to give (3S,4S)-3-benzylaminomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine as a colorless tar (1.18 g).

Provenance & Evidence