Activation of Anthraquinone’s Electrophilicity by Light for a Dynamic C–O Bond
Vasily Bykov, Stepan A. Ukhanev, Igor А. Ushakov, Анна В. Вологжанина, Evgenii Antsiferov, L. S. Klimenko, Andrey G. Lvov
Abstract
Coupling of photoswitching with dynamic covalent chemistry enables control of the formation and cleavage of covalent bonds by light irradiation. peri -Aryloxyanthraquinones feature an exclusive ability to switch electrophilicity by interconversion between para - and ana -quinone isomers, which was used for the first time for the implementation of a dynamic C–O bond. Photogenerated ana -isomers undergo a concerted oxa -Michael addition of phenols to give hitherto unknown 4-hydroxy-10,10-diaryloxyanthracen-9-ones. These species were found to be in equilibrium with the corresponding ana -quinones, thus forming a dynamic covalent system of a new type. Withdrawal of the colored ana -quinones from the equilibria by visible light irradiation resulted in two para -quinones with “locked” aryloxy groups.