Deoxygenation of Hydroquinones as a General Route to Norbornane-Fused Aromatic Systems: An Entry into Substituted and Functionalized Dimethano- and Methanoanthracenes

Abstract

A high-yielding route to substituted and functionalized dimethanoanthracenes by the Pd-catalyzed deoxyenation of the corresponding hydroquinone precursors is described. Attempts were made to deoxygenate the 9,10-dimesylate, ditosylate, and ditriflate derivatives of <i>anti</i>-dimethanoanthracene <b>1a</b>, and it was found that under the studied conditions only the ditriflate <b>8a</b> gave the corresponding deoxygenated aromatic scaffold. Optimization of the reaction conditions identified the Pd­(OAc)₂/dppf tandem as a suitable catalytic system for this transformation. The presented strategy was further extended to a novel and efficient synthetic route to methanoanthracenes employing a one-pot Pd-catalyzed deoxygenation/hydrogenation sequence