Ring expansion of prophins with ethoxycarbonylnitrene

Abstract

The reactions of ethoxycarbonylnitrene with aetioporphyrin I and octaethylporphyrin give ring-expanded meso-homoazaporphins resulting from attack at a meso-double bond. Heating the meso-homoazaporphins in the solid state or in solution causes ring contraction to the meso-ethoxycarbonylaminoporphins. Ring contraction of the meso-homoazaporphins to the metal meso-ethoxycarbonylaminoporphins occurs rapidly, at room temperature in the presence of copper or zinc acetate. Reaction of copper or zinc porphins with ethoxycarbonylnitrene gives the corresponding metal meso-ethoxycarbonylaminoporphins directly.