SYNTHESIS OF INDENONES VIA PALLADIUM-CATALYZED ANNULATION OF INTERNALALKYNES

A number of 2,3-disubstituted 1-indenones have been prepared in fair t o good yields by treating o-iodo- or o-bromobenzaldehyde with various internal alkynes in the presence of a palladium catalyst. Syntheticall y, the methodology provides an especially convenient route to stable h indered indenones containing aryl, silyl, and tert-alkyl groups. The r eaction is believed to proceed through a palladium-(IV) intermediate, and the regiochemistry of the reaction is controlled sterically.