Ligand‐Free Copper‐Catalyzed Allenylative CP Coupling of Propargylic Acetates with H‐Phosphine Oxides

The extra‐ligand‐free CuTC‐catalyzed CP cross coupling reaction of propargylic acetates with H‐phosphine oxides is reported to afford allenylphosphine oxides. The reaction took place efficiently with diphenylphosphine oxide and electron‐deficient di(4‐fluorophenyl)phosphine oxide, but less effectively with electron‐rich ones such as di(4‐methoxylphenyl)phosphine oxide and dialkylphosphine oxides. H‐phosphine oxides themselves may serve as the ligand.