Iron-Catalyzed C–N Bond Formation via the Beckmann Rearrangement

Abstract

A simple, iron-based catalytic system allows for facile Beckmann rearrangement of various oximes. The mild conditions avoid the use of harsh or expensive acids, and the reactions do not require an ­inert atmosphere. Additionally, a range of amides can be accessed through this transformation.

Key words

iron - amides - Beckmann rearrangement - oximes - Lewis acid

• References and Notes

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• 16 Iron-Catalyzed Beckmann Rearragnment; General Procedure: To an oven-dried 20 mL vial containing FeCl₃ (24.3 mg, 0.15 equiv), was added a solution of oxime (1 mmol) in DCE (10 mL) and the mixture was stirred until FeCl₃ was completely dissolved (10–15 min). To this solution was added AgSbF₆ (154.6 mg, 0.45 equiv), then the vial was capped and put into mechanical shaker at 80 °C for 24 h. The mixture was filtered through Celite with CH₂Cl₂ (100 mL) and concentrated to give a residue, which was purified by silica flash chromatography using hexanes and ethyl acetate in appropriate combination based on the R_f of the desired product.