First Synthesis of Azachlorins and Azacorrins with a N‐Atom in β‐Pyrrolic Positions

Azachlorins 7 and 11, and azahexadehydrocorrin rac-10 are novel structural types of tetrapyrrolic macrocycles. Synthesis of the target structures bearing N-atoms in the β-periphery of the macrotetracycles could be achieved by attaching an imidazole moiety 4 to the tricyclic Ni complex rac-5, followed by cyclization. Depending on the central metal ion of the bilin intermediates rac-6a and rac-6b, chlorin- or corrin-type structures were formed by cyclization.