Facile synthesis of N,N′-dimethylated N-confused porphyrins

N-Confused tetraarylporphyrins react with CH3I in the presence of Na2CO3 to give, in high yield, N,N′-dimethylated N-confused porphyrin salts, which are mixtures of structural isomers. The structures of the major isomers were determined by X-ray diffraction and NMR spectroscopic analyses. These N,N′-dimethylated N-confused tetraarylporphyrin salts generate singlet oxygen when irradiated at long wavelengths in the visible region, and therefore, are potential sensitizers for photodynamic therapy.