Visible Light-Driven Contra-Thermodynamic Functional Group Transposition of Chalcones.

α,β-unsaturated ketones demonstrate well-precedented reactivity profiles, such as conjugate addition, hetero-Diels-Alder, and [2+n] cycloaddition reactions. They are also used in medicine, fluorescent probe design, corrosion inhibition, and photoinitiation. While functional group transposition has grown in popularity over the past decade, its deployment for the reorganization of 1,3-diaryl enones (i.e., chalcones) has not been achieved. Herein, we disclose visible light-driven conditions to directly access transposed 1,2-diaryl enone chemical space from chalcones, creating a new contra-thermodynamic reactivity paradigm for this storied motif. This method is compatible with a range of functional group patterns and consistently delivers the products in excellent yields. Preliminary mechanistic experiments lend support to key steps underpinning the reaction mechanism while also indicating the origin of the exceptional selectivity. This work creates a new retrosynthetic disconnection while also paving the way for naturally occurring chalcones to be used as substrates in skeletal reorganization reactions, accelerating the discovery of new therapeutics and functional materials.