Correction to: Nature Chemistry https://doi.org/10.1038/s41557-018-0081-0, published online 25 June 2018.

In the version of this Article originally published, on the right side of Fig. 4b, the ‘Aromatic cycle’ label was erroneously shifted outside of the central circular arrow into a position on part of the reaction cycle. This has been corrected in the online versions of the Article.