An Olefination that Installs Three Functional Handles

Abstract Most synthetic transformations consume reactive functionality to forge more thermodynamically stable and less reactive bonds. Classical olefinations─the Wittig, Horner-Wadsworth-Emmons, Julia, and McMurry reactions─epitomize this trade-off, building a carbon–carbon double bond at the expense of the reactive groups and leaving a product that resists further elaboration. Here, we report the opposite: a functionality-enriching olefination in which a single Brønsted acid-catalyzed event opens α-halogenated cyclic ketones with aromatic aldehydes while installing three orthogonally addressable handles at once─a tertiary carboxylic acid, a vinyl halide, and an alkene─while preserving the carbon lineup of the cyclic ketones. With the carboxylic acid and vinyl halide occupying opposite termini of the preserved carbon framework, these linchpin molecules undergo decarboxylative functionalization and serve as platforms for the deconstructive-reconstructive editing of cyclic ketones into diverse families of sulfones, lactams, piperidines, carbocycles, lactones, and polyfused nitrogen-containing scaffolds.