O2-Mediated transformation of 9-phenanthrenol: an approach to the synthesis of phenanthrenyl ketal and 9-fluorenones

We report herein a novel pathway for oxidation of 9-phenanthrenol, giving an unprecedented ketal structure. 9-Fluorenone and its derivatives can be synthesized in good to high yields with good functional group tolerance using the ketal or 9-phenanthrenols as substrates. Decomposition and formation processes of the ketal have been investigated.