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

Provenance & Evidence