From thioether substituted porphyrins to sulfur linked porphyrin dimers: an unusual S_NAr via thiolate displacement?

Treatment of meso 2-ethylhexyl-3-mercaptopropionate substituted porphyrins with base at room temperature generated a porphyrin thiolate anion which in situ reacted in a nucleophilic aromatic substitution (S_NAr) reaction with remaining thioether derivative. This reaction yielded S-linked bisporphyrins in good yields, with mechanistic insight obtained via displacement reactions. Additionally, S_NAr of the thioether chain was achieved using S- and organolithium nucleophiles.