Synthesis of N‑Heterocycle-Ligated Porphyrins Using Iodobenzene Diacetate Enabled Regioselective Cross-Dehydrogenation of Porphyrins and NH-Heteroaromatics

Preparation
of diverse meso-functionalized porphyrins
involves iodine(III)- and copper triflate-promoted dehydrogenative
coupling of meso-free porphyrins and appropriate
NH-free heterocycles. Reaction conditions involving the stable and
recyclable iodobenzene diacetate reagent are compatible with a range
of NH-free heterocycles (acridone, phenoxazine and phenothiazine,
carbazole, β-carbolin triazoles, imidazole, pyrazole, indazole,
and tetrazole) and porphyrins to access diversely functionalized A3B, A2BC, and A2B2 porphyrins
in moderate to good yields. The prepared heterocycle-appended porphyrins
exhibit modestly red-shifted Soret and Q bands in the absorption spectra.