Carbon-Carbon Bond Formation through Palladium Homoenolates

Homoenolates represent a useful class of umpolung synthons with the potential to greatly streamline complex molecule synthesis. Because the direct formation of homoenolates faces many limitations, a number of alternative approaches to this synthon have been developed. In this review we present the main strategies for the generation and application of palladium homoenolates. We highlight the merits and limitations of each approach, and comment on aspects of the mechanism of these reactions where appropriate. 1Introduction 1.1Palladium Homoenolates 1.2Scope of this Review 2Generation of Palladium Homoenolates via Transmetalation of Pre-Formed Homoenolates 2.1Transmetalation of Zinc Homoenolates 2.2Transmetalation of Boron Homoenolates 2.3Transmetalation of Indium Homoenolates 3Catalytic Generation of Palladium Homoenolates by Ring Cleavage of Cyclopropanol Derivatives 4Generation of Homoenolates via Palladium-Catalyzed C-H Activation 5Generation of Homoenolates via Palladium-Catalyzed Isomerization of Enolates 6Conclusions and Outlook