Facile Elaboration of Porphyrins via Metal-Mediated Cross-Coupling

Article abstract of DOI:10.1021/jo00074a027

Metal-mediated cross-coupling methodologies have been successfully employed to porphyrinic systems, providing a powerful, versatile, and general synthetic approach for the fabrication of elaborated porphyrin structures.A large number of coupling reactions have been carried out at two halogenated porphyrin templates, <2-bromo-5,10,15,20-tetraphenylporphinato>zinc and <5,15-dibromo-10,20-diphenylporphinato>zinc, generating a variety of porphyrins, 10 of which are novel: <2-n-butyl-5,10,15,20-tetraphenylporphinato>zinc(II), <2-(2,5-dimethoxyphenyl)-5,10,15,20-tetraphenylporphinato>zinc(II), <2-(9-anthracenyl)-5,10,15,20-tetraphenylporphinato>zinc(II), <2-vinyl-5,10,15,20-tetraphenylporphinato>zinc(II), <2,5,10,15,20-pentaphenylporphinato>zinc(II), <2-isobutyl-5,10,15,20-tetraphenylporphinato>zinc(II), <2-(pentafluorophenyl)-5,10,15,20-tetraphenylporphinato>zinc(II), <5,15-bis<<2-(4'-methyl-2'-pyridyl)-4-pyridyl>methyl>-10,20-diphenylporphinato>zinc(II), <5,15-dimethyl-10,20-diphenylporphinato>zinc(II), <5,15-divinyl-10,20-diphenylporphinato>zinc(II), <5,15-bis(2,5-dimethoxyphenyl)-10,20-diphenylporphinato>zinc(II), and <5,15-bis(pentafluorophenyl)-10,20-diphenylporphinato>zinc(II).The structures of <2,5,10,15,20-pentaphenylporphinato>zinc(II) and 5,15-bis(pentafluorophenyl)-10,20-diphenylporphyrin have been determined; X-ray data are as follows: P2₁/n with a = 21.425(4) Angstroem, b = 9.718(1) Angstroem, c = 24.905(2) Angstroem, β = 110.83(1) deg, V = 4846(3) Angstroem³, d_calc = 1.260 g cm^-3, and Z = 4 for the former; and P2₁/c with a = 15.223(2) Angstroem, b = 10.162(1) Angstroem, c = 12.375(2) Angstroem, β = 112.75(2) deg, V = 1765.6(9) Angstroem³, d_calc = 1.495 g cm^-3, and Z = 2 for the latter.This study demonstrates that cross-coupling reactions at the porphyrin periphery are seemingly not subject to the steric or electronic constraints that often limit the scope of these reactions in simple aryl and vinyl systems.