Hydrogen-bonded xanthones as potential UV absorbers. The synthesis of xanthones from bio-renewable cardanol utilizing a ceric ammonium sulfate (CAS) mediated oxidation reaction

The synthesis of hydrogen-bonded xanthones using the bio-renewable phenol, cardanol is described. Cardanol was initially converted into hydroxy-benzophenones. These benzophenones were converted into xanthones utilizing an oxidative ceric ammonium sulfate (CAS) mediated reaction. Subsequent ruthenium-mediated late-stage oxidation of the xanthones provided hydrogen-bonded xanthones, which displayed good UVA and UVB absorbing properties.