Coloured Artefacts Formed by Oxidation of Benzene‐1,2,4‐triol and β‐Dopa During the Extraction of Cortinarius violaceus (Agaricales) with Alcohols

An array of coloured artefacts was formed upon extraction of the mushroom Cortinarius violaceus with methanol. The structures of these pigments were determined by spectroscopic investigations, including NMR and mass spectrometric analyses. Cortiviolate A and dihydrocortiviol A arise by oxidative dimerization of benzene-1,2,4-triol, and cortiviolate B is formed by an unprecedented oxidative rearrangement of β-dopa. The oxidations are caused by iron(III) ions, released from the iron complex of (R)-β-dopa – the native violet pigment of the mushroom. In the course of these investigations, syntheses of the cortiviolates, dihydrocortiviol A, gomphilactone, and two related dilactones were carried out.