Completely Regioselective Synthesis of Directly Linkedmeso,meso andmeso,β Porphyrin Dimers by One-Pot Electrochemical Oxidation of Metalloporphyrins

The metal ion determines the reactivity upon electrochemical oxidation of metal porphyrins that are unsubstituted at the meso position. Thus, with Cu2+, Pd2+, and Ni+2 as the central ion (and for the free porphyrin base), directly linked meso,β porphyrin dimers 2 were formed, while Mg and Zn complexes afforded the corresponding directly linked meso,meso porphyrin dimers 1. Ar=3,4-tBu2C6H3.