A chromatography-free synthesis of meso -tetrakis(4-formylphenyl)porphyrin and meso -tetrakis(3-formylphenyl)porphyrin: Versatile synthons in supramolecular and macromolecular chemistry

A facile synthetic strategy was developed for the synthesis of meso -tetrakis(4-formyl-phenyl)porphyrin and meso -tetrakis(3-formylphenyl)porphyrin from commercially available starting materials. This method gives facile access to practical amounts of these synthons in high purity and good overall yield, without employing laborious chromatographic separations. The reduction of the respective carboxylic acid-functionalized porphyrins by LiAlH₄ afforded the tetra(benzylalcohol)porphyrin intermediates, subsequently utilized in a Parikh-Doering oxidation to selectively afford the desired tetraformylated products. The inherent ease of synthesis of these porphyrin building blocks provides a convenient pathway for the synthesis of various macromolecular and supramolecular architectures for applied chemical technologies.