Synthesis of 2,3-Benzobicyclo[3.3.1]non-2-enes via a Cascade of Domino Carbocation Migration/Interrupted Ritter Reaction and Dienone-Phenol Rearrangement

The 2,3-benzobicyclo[3.3.1]non-2-ene scaffold is a bridged backbone of many bioactive natural products. The development of a concise tactic toward this architecture is of keen interest and highly challenging. Herein, we disclose a novel cascade protocol for realizing this target. This approach relies on a domino sequence of carbocation rearrangement and Ritter reaction of the taiwaniaquinoid scaffold derivatives. A process of dienone-phenol rearrangement was postulated to be involved. Several potentially useful compounds with this intricate bridged ring were obtained in good overall yields (59-83%, over 2 steps).