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

Participants

Reaction Steps

The mixture (310 mg) of (3S,4R)-3-aminomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine and 3-aminomethyl-1-benzyloxycarbonyl-3-pyrroline was dissolved in methanol (4 mL). To this solution, molecular sieves 4A (130 mg) and then benzaldehyde (0.13 mL) were added and the mixture was stirred at room temperature for 1 hour. Subsequently, a borane/pyridine complex (0.19 mL) was added and the reaction mixture was further stirred at room temperature for 4 hours. 6 mol/L hydrochloric acid (2 mL) was then added and the mixture was stirred at room temperature for 1 hour, followed by addition of a 30% aqueous solution of sodium hydroxide to make the mixture basic. The mixture was then extracted with diethyl ether (3×10 mL). The diethyl ether layers were combined and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluant: dichloromethane: methanol=10:1) to give (3S,4R)-3-benzylaminomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine as a pale yellow oil (177 mg).

Provenance & Evidence