Synthesis of the Corrole Macrocycle

The first efforts to prepare corrole were presented by A. W. Johnson in 1960. They involved an attempt to effect ring closure of a metallo-dibromo 

In spite of the above, and in spite of what might have been inferred from the early papers, the Cu and Co oxacorroles 2.17 and 2.18 were apparently successfully made by the Johnson group. These, in turn, were later demetalated successfully using sulfuric acid to give the metal-free species 2.19. This metal-free corrole was reported to react further with various metal salts to afford the corresponding meta-lated derivatives. Unfortunately, however, specific details as to which metals were used and the properties of the resulting metallocorroles were never presented in the open literature. They are thus not known to the present authors. 

At about the same time that the oxacorroles were being studied, Johnson, et al. successfully prepared the metallo-derivatives of the imino- and A-methylimino- 

An alternative route to these bifuran-containing corroles was also pursued it involved carrying out an acid-catalyzed condensation between the diformyldifuryl sulfide 2.43 and an appropriate diacid dipyrrylmethane species (e.g., 2.35-2.37) 

The bifuran-derived corrole derivative 2.39 was later subjected to metalation 

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