Spirocyclic molecules have long attracted the attention of organic chemists. In addition to the synthetic challenge they present in establishing a fully substituted carbon center, spirocyclic frameworks are found at the core of numerous natural products, many of which exhibit desirable biological activity. A common approach to the construction of this valued class of molecules relies on the oxidative-dearomatization of electron-rich arenes to form highly reactive cationic intermediates that undergo spirocyclization via the attack of an intramolecular nucleophile. In contrast to these methods that require stoichiometric oxidants to achieve the desired transformation, we have developed a catalytic method for the spirocyclization of aryl-alkynoate esters that proceeds through a redox neutral process, thereby obviating the need for external oxidants. The key C-C bond-forming step occurs via the dearomatization of the arene, which occurs concurrent with alkyne reduction, to yield spirocyclic lactones in good to excellent yields under mild conditions.

Redox-neutral catalytic spirocyclization of aryl-alkynoate esters

248th National Meeting (2014)

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