Facile Synthesis of Spirocyclic Ketones via Gold (I)-Catalyzed Claisen-Type Rearrangement of Cyclic 8-Aryl-2,7-enyn-l-ols

The gold(I)-catalyzed Claisen-type rearrangement of cyclic 8-aryl-2,7-enyn-1-ols proceeds via a cationic allylic vinyl ether gold intermediate to give spirocyclic ketones. The reaction proceeded via attack of the hydroxyl group onto the gold-activated alkynes followed by [3,3]-sigmatropic rearrangement to generate the spirocyclic ketones. This transformation can be applied to the synthesis of aza- and oxaspirocyclic ketones from cyclic 8-aryl-2,7-enyn-1-ols bearing an N-sulfonamide or an oxygen atom linkage in the tether and the gold(I) catalyst.