An improved synthesis of 5,15‐diaryloctaalkylporphyrins

Abstract

Abstract The title compounds were prepared from an aromatic aldehyde and bis(3‐ethyl‐4‐methyl‐2‐pyrrolyl)‐methane in acetonitrile in the presence of catalytic amount of trichloroacetic acid, followed by p ‐chloranil oxidation. The reaction conditions employed here are milder than those previously reported, allowing efficient preparation of porphyrins with acid‐labile groups such as cyclic acetals, for which the previous method provided no direct synthetic access. Using the new method, aromatic aldehydes with acid‐labile groups, as well as sterically hindered aldehydes, gave the corresponding porphyrins in satisfactory yields (50–90%). This method therefore can be widely utilized for synthesis of 5,15‐diaryloctaalkylporphyrins.