Synthesis of four regioisomeric Ni(ii) azacorroles via oxidative ring-expansion of prefunctionalised norcorroles†

We explored the synthesis of four regioisomeric formylated and brominated azacorroles via oxidative insertion of prefunctionalised Ni(II) norcorroles. We also found that the reaction of Ni(II) azacorroles with the Vilsmeier reagent afforded 2- and 3-formylazacorroles. The structures of all the products were characterised thoroughly by high-resolution mass spectrometry, NMR and UV-vis absorption spectroscopy together with X-ray diffraction analysis. The synthesis of four regioisomers of formyl- and bromoazacorroles allowed a detailed study of the substituent effect depending on the position of the functionality.