Linear tetrapyrroles attracted interest of chemists and biochemists, due to the interesting optical properties, and

biological importance both in photosynthesis and photoreceptor. In particular, the dynamic structural changes

of linear tetrapyrroles such as cis-trans isomerization and coordination to various metal ions are unique

features of this class of compounds. We found that 19-phenoxybilinones undergoes cyclization upon reaction with

metal ions to yield 5-oxaporphyrin metal complexes. In this paper, we summarizes the scope and limitation of

this metal-induced cyclization of 19-phenoxybilinones, and report optical properties of the metal complexes of

5-oxaporphyrin.