Regioselective Carbon-Halogen Bond Formation in the Reaction of Ag(III) N-Confused Porphyrin Complex with HCl or HBr

A facile inner halogenation of Ag(III) NCP complex 1 is reported. Treatment of 1 with 2N HCl and 1N HBr gave 2 and 4, respectively. A demetallized product 3 was formed as a trace side product when dilute acids were applied and as a predominant product when treated with concentrated acids. The importance of the C3-ethoxy group for the halogenation reactions was experimentally indicated. Treatment of 1 with 4N H2SO4 gave carbaporpholactam 6 in good yield. Halide anions are suggested to accelerate the demetallation reaction of 1.