Ligand-Free Copper-Catalyzed Negishi Coupling of Alkyl-, Aryl-, and Alkynylzinc Reagents with Heteroaryl Iodides

Reported herein is an unprecedented ligand‐free copper‐catalyzed cross‐coupling of alkyl‐, aryl‐, and alkynylzinc reagents with heteroaryl iodides. The reaction proceeds at room temperature for the coupling of primary, secondary, and tertiary alkylzinc reagents with heteroaryl iodides without rearrangement. An elevated temperature (100 °C) is required for aryl–heteroaryl and alkynyl–heteroaryl couplings. Simply copper: Primary, secondary, and tertiary alkylzinc reagents couple with heteroaryl iodides in the presence of ligand‐free CuI without complications arising from β‐hydride elimination and rearrangement. The reactions can also be extended to the coupling of aryl‐ and alkynylzinc reagents. DMF=N,N‐dimethylformamide.