Synthesis of 2,4-Disubstituted Oxazoles by a Copper-Catalyzed [3+2] Annulation/Olefination Cascade between Amides and IIII/PV Hybrid Ylides

Abstract We report a novel and efficient method for oxazole synthesis through a copper-catalyzed [3+2] annulation/olefination cascade between readily available iodonium–phosphonium hybrid ylides and amides. An unprecedented α-phosphonium Cu carbenoid acts as the key intermediate. This method features excellent regioselectivity with mild reaction conditions and a broad substrate scope. Its synthetic utility is demonstrated by its application in late-stage functionalizations and the rapid synthesis of a chiral ligand based on an oxazole motif.