Targeted Synthesis of Regioisomerically Pure Dodecasubstituted Type I Porphyrins through the Exploitation of Peri-interactions.

A targeted synthesis of dodecasubstituted type I porphyrins that utilizes the reaction of unsymmetrical 3,4-difunctionalized pyrroles and sterically demanding aldehydes was developed. This way, type I porphyrins could be obtained as the only type isomers, likely due to a minimization of the steric strain arising from peri-interactions. Uniquely, this method does not depend on lengthy precursor syntheses, the separation of isomers, or impractical limitations of the scale. In addition, single-crystal X-ray analysis was used to elucidate the structural features of the macrocycles.