A new route to protoporphyrins has been developed by Swiss chemists.

Their approach side-steps the standard MacDonald condensation reaction and allows them to couple an unsymmetrical diiodo dipyrrylmethane with a known dipyrrylmethane without resorting to an oxidizing agent. The team explains that the method is well suited to making protoporphyrin IX derivatives on the several-hundred gram scale and also avoids the standard chromatographic step.

An added advantage is that the route also avoids the need to use any reagents of animal origin and so also avoids other potential contaminants.

• Total Synthesis of Hematoporphyrin and Protoporphyrin: A Conceptually New Approach
  P. Martin, M. Mueller, D. Flubacher, A. Boudier, H.-U. Blaser, D. Spielvogel
  Org. Proc. Res. Dev. 2010, 14.
  DOI: 10.1021/op100036c