A decarboxylativeintramolecularaziridination reaction of alkene‐tethered 4H‐isoxazol‐5‐ones with a palladium/phosphine catalyst gave 1‐azabicyclo[3.1.0]hex‐2‐enes in moderate to high yields (see scheme; dba=dibenzylideneacetone). The resulting N‐fused bicyclic aziridines readily reacted with various reagents to afford ring‐opening pyrroline derivatives.
A phosphine‐free iridium‐catalyzed reaction of isoxazol‐5(4H)‐ones (isoxazolones) has been developed, and affords 2H‐azirines through decarboxylation and ring contraction. This method provides an efficient and environmentally benign protocol which could replace the conventional approaches used to synthesize 2H‐azirines.