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 Cs(2)CO(3). 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.