The reaction of 2-formyl-5,10,15,20-tetraphenylporphyrin with aryl methyl ketones and ammonium acetate, in the presence of La(OTf)3, affords benzoporphyrins and 2-(2,6-diarylpyridin-4-yl)porphyrins. This methodology was used to prepare, for the first time, a 2-(2,2′:6′,2′′-terpyridin-4′-yl)porphyrin. The structures of two 2-(2,6-diarylpyridin-4-yl)porphyrins were confirmed by single-crystal X-ray diffraction.
