Microwave-assisted synthesis of non-substituted tripyrrane, tetrapyrrane and pentapyrrane

The microwave-assisted one-step condensation of aqueous formaldehyde with pyrrole was successfully applied for the preparation of non-substituted tri-, tetra- and pentapyrranes with reasonable yields. All three compounds are important precursors to advanced porphyrins and porphyrin analogs. The advantages of this method are short reaction times, clean reaction mixtures and work in the non-toxic and environment friendly solvent—water.