Electron Deficient Porphyrins III. Facile Syntheses of Perfluoroalkylporphyrins Including Water Soluble Porphyrin

A variety of 3-perfluoroalkyl pyrroles were prepared by reaction of β-perfluoroalkyl α,β-unsaturated carbonyl compounds with p-tolylsulfonylmethyl isocyanide in moderate yields. Tetrakis(perfluoroalkyl)porphyrins were readily obtained by oxidative cyclization of 3-alkyl-2-hydroxymethyl-4-perfluoroalkylpyrroles in acidic media, including water-soluble 3,8,13,18-tetrakis(p-carboxybenzyl)-2,7,12,17-tetrakis(trifluoromethyl)porphyrin. The pKa value for the monoprotonation of its inner nitrogen is less than 1, while that of Copro-I is 7.2. Diprotonation at the inner nitrogen occurs only in concd HCl, while the pKa value of the corresponding non-fluoro porphyrin is 4. The reduction potential of 3,8,13,18-tetrakis(p-methoxycarboxybenzyl)-2,7,12,17-tetrakis(trifluoromethyl)porphyrin was shifted by 580 mV to a less negative value.