An efficient one-flask synthesis of N-confused tetraphenylporphyrin

[GRAPHICS] N-Confused meso-substituted porphyrin is a porphyrin isomer previously available from one-flask porphyrin syntheses as a low-yield byproduct (<7.5%). We have found that methanesulfonic acid catalyzed condensation of pyrrole and benzaldehyde followed by DDQ oxidation provides N-confused tetraphenylporphyrin (NC-TPP) in up to 39% yield in analytical scale experiments, Preparative synthesis provided an isolated yield of 35% (800 mg), This represents a >5-fold yield improvement and makes significant quantities of NC-TPP readily available.