Mechanism of Purpurogallin Formation: An Adduct from 3‐Hydroxy‐o‐benzoquinone and 4,5‐Dimethyl‐o‐benzoquinone

The adduct 2 has long been postulated as an intermediate in the formation of purpurogallin 1 from pyrogallol. The adduct 5, formed from the o-benzoquinones 3 and 4, exhibits extensive structural analogy to 2 and thus supports previous conceptions on the mechanism of purpurogallin formation.