Ammonium Acetate → 5-(2-Aminopropyl)benzofuran

Participants

Reaction Steps

A mixture of 1 gm (5.7 mMol) 1-(benzofur-5-yl)-2-propanone, 8.9 gm (115 mMol) ammonium acetate, and 2.8 gm powdered 3A molecular sieves in 60 mL methanol was stirred at room temperature for 1 hour. To this mixture were then added 5.8 mL (5.8 mMol) sodium cyanoborohydride (1.0 M in tetrahydrofuran) and the mixture was stirred for an additional 5 hours at room temperature under a nitrogen atmosphere. The reaction mixture was then filtered over a pad of celite and the pad was rinsed with 200 mL methanol and 200 mL dichloromethane. The combined filtrates were concentrated under reduced pressure and the resultant residue was partitioned between 200 mL dichloromethane and 20 mL water. The mixture was washed with two 25 mL portions of 5 N sodium hydroxide. The combined aqueous extracts were extracted with three 100 mL portions of dichloromethane. All of the organic phases were combined, washed with 25 mL 0.1 N sodium hydroxide followed by 25 mL water, dried over magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel chromatography, eluting with a gradient of dichloromethane containing 6% methanol to dichloromethane containing 9% methanol and 9% concentrated ammonium hydroxide. Fractions containing product were combined and concentrated under reduced pressure to provide 0.498 gm (49%) of 1-(benzofur-5-yl)-2-aminopropane.

Provenance & Evidence