Direct C−H Arylation and Alkenylation of 1-Substituted Tetrazoles: Phosphine As Stabilizing Factor

Direct arylation and alkenylation of 1-substituted tetrazoles was achieved via Pd catalysis in the presence of CuI and Cs₂CO₃. Unlike the related reactions of imidazoles and purines, phosphine ligand was necessary to prevent the intermediate tetrazolyl-Pd^II species from fragmentation into the corresponding cyanamide. Various 1,5-disubstituted tetrazoles were prepared with good to excellent isolated yields.