Synthesis of Allyl Allenes through Three‐Component Cross‐Coupling Reaction of N‐Tosylhydrazones, Terminal Alkynes, and Allyl Halides

Three's a crowd: Tri- and tetrasubstituted allyl allenes can be easily accessed by this Cu(I)-catalyzed three-component coupling reaction of N-tosylhydrazones, terminal alkynes, and allyl halides. The reaction proceeds through a mechanism involving copper carbene migratory insertion.