Halogenation of Unsaturated Amides: Synthesis of Halogenated (Spiro)Oxazolines

Abstract Carbon‐halogen (F, Cl, Br, I) bond was constructed through halogenation of unsaturated amides using electrophilic halogen reagents as oxidant and halogen source. Various halogenated 2‐oxazolines (85 examples) and spirooxazolines (43 examples) were synthesized in high to excellent yields (up to 99 % isolated yield) through the mild, metal‐free and efficient halogenation reaction. This method provided an alternative method for construction of carbon‐halogen bond in organic synthesis, as well as synthesis of halogenated (spiro)2‐oxazoline derivatives. The reaction follows an “intermolecularly electrophilic addition/intramolecularly nucleophilic attack” cascade according to the supposed mechanism.