One-pot synthesis of functionalized, highly substituted porphodimethenes

Treatment of nickel(II)complexes of 2,3,7,8,12,13,17,18-octaethylporphyrin with a combination of organolithium and alkyl iodide reagents gives convenient access to di-, tri-and tetra-meso-substituted porphodimethenes with different substituent patterns in a one-pot synthesis. The substituents can possess a variety of functional groups like -I, COOEt and CN. The reaction is stereospecific and gives the target compounds in good yields (50–80%). 5,15-Diarylporphyrins react in a different manner. Upon treatment with n-butyllithium followed by addition of alkyl iodides with small residues (e.g. ethyl, cyanomethyl) they undergo a trialkylation yielding e.g. (5-butyl-5,5′,15-triethyl-10,20-diphenylporphyrinato)nickel(II). Highly substituted porphodimethenes can also be prepared in one step and good yield (∼60%) using di-meso-2,3,7,8,12,13,17,18-octa-β-substituted porphyrins, LiR and DDQ in good yield (∼60%). The conformations of the synthesized porphodimethenes were investigated via two dimensional NMR, NOE and X-ray crystallographic experiments.