Syntheses of water-soluble cationic porphyrins and chlorins

Reactions of vinylchlorins and vinylporphyrins with N,N-dimethylmethyleneammonium iodide ("Eschenmoser's Reagent") gives Mannich adducts in which substitution (with CH₂NMe₂) has taken place on the terminal carbon of the vinyl group to yield a trans-3-(N,N-dimethylaminomethyl)prop-1-enyl derivative. Under no circumstances was meso substitution observed. Use of zinc(II) vinylchlorins or zinc(II) vinylporphyrins afforded the corresponding zinc(II) trans-vinyl adducts at a significantly faster rate than the metal-free substrates. Reaction of Eschenmoser's reagent with deuteroporphyrin-IX dimethyl ester (29) (which possesses two peripherally unsubstituted positions) produces the bis-(N,N-dimethylaminomethyl) product (30). Treatment of the dimethylamino chlorins and porphyrins with methyl iodide, in all cases, gives an excellent yield of the corresponding quaternary ammonium iodides, and these compounds are highly water-soluble.