Journal of Organic Chemistry 2006-11-10

An N-heterocyclic carbene-catalyzed [8 + 3] annulation of tropone and enals via homoenolate.

Vijay Nair, Manojkumar Poonoth, Sreekumar Vellalath, Eringathodi Suresh, Rajasekaran Thirumalai

Index: J. Org. Chem. 71(23) , 8964-5, (2006)

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Abstract

A novel protocol for the annulation of tropone to enals involving nucleophilic heterocyclic carbene (NHC) catalyzed homoenolate formation has been developed. Interestingly, the reaction led to bicyclic delta-lactones instead of the expected gamma-spirolactones, presumably by the uncommon [8 + 3] annulation pathway. The strategy works well with a variety of enals.