Functionalized α,α-Dibromo Esters through Claisen Rearrangements of Dibromoketene Acetals

Allylic alcohols can be transformed into gamma,delta-unsaturated alpha,alpha-dibromo esters through a two-step process: formation of a bromal-derived mixed acetal, followed by tandem dehydrobromination/Claisen rearrangement. The scope and selectivity of both steps have been investigated. The product alpha,alpha-dibromo esters were subjected to various carbon-carbon bond-forming reactions, oxidations, and lactonizations.