Synthesis of symmetric meso-H dipyrrin hydrobromides from 2-formyl pyrroles

Abstract

The reaction of 2-formyl pyrroles in acidic methanol gives the corresponding symmetric, meso-H 4,6-dipyrrin hydrobromides. This convenient strategy involves initial deformylation under the acidic conditions, followed by immediate in situ reaction of the resulting α-free pyrrole with the remaining 2-formyl pyrrole in solution to give the dipyrrin hydrobromide salt in good yield.