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. (C) 2002 Elsevier Science Ltd. All rights reserved.