PhI(OAc)2‐Mediated One‐Pot Oxidative [3+2] Cycloaddition/ Heterocyclization Reactions of Aldoximes with N‐Arylmaleimides: A Facile Access to N‐Substituted Pyrrolo‐Isoxazoles

Abstract A convenient and efficient metal‐free oxidative [3+2] cycloaddition reaction of N ‐arylmaleimides with nitrile oxides generated in situ from the corresponding aldoximes using diacetoxyiodobenzene (DIB) as hypervalent iodine reagent under mild conditions has been established. The one‐pot oxidative cycloaddition afforded corresponding bioinspired bicyclic isoxazole/pyrrolo‐isoxazole derivatives in up to 91 % yield at room temperature. To demonstrate the efficacy of this methodology, the reaction was scaled up to the gram‐scale showing synthetic potential in industrial application. The one‐pot fashion makes the strategy highly time‐economic, atom‐economic and minimizes chemical waste by circumventing several purification steps.