Isolation, structure, and properties of quinone-aci tautomer of a phenol-nitro compound related to eugenoxyacetic acid

Treatment with excess nitric acid in acetic acid revealed that eugenoxyacetic acid underwent an unexpected ether cleavage, a normal nitration, and then an unexpected electrophilic addition to the double bond of the side chain that led to the formation of a dinitro compound which subsequently converted to a sensitive, reactive quinone-aci compound. The structure of the quinone-aci compound (1) and its derivatives (2–6) was established by 1D- , 2D NMR, MS spectra, and chemical methods. In addition, the XRD structure of compound 2 derived from 1 was established. A double tautomerization of 1 in solution was studied by the LC–UV–MS method.