Abstract
The 18π-σ³- and 22π-σ⁴-phosphaporphyrins were successfully prepared by an acid-promoted condensation between a phosphatripyrrane and a 2,5-bis[hydroxy(phenyl)methyl]pyrrole, and their structures, aromaticity, and optical and electrochemical properties were disclosed. Notably, a σ⁴-phosphaporphyrinogen and the 18π-σ³-phosphaporphyrin undergo oxidative -extension at the peripherally fused carbocycle to afford the 22π-σ⁴-phosphaporphyrin.