Visible-light or sunlight photoredox-catalyzed β-selective acylation of alkenes to access α,β-unsaturated ketones†

With increasing concerns regarding the energy crisis and environmental changes, the development of sunlight-based methods for organic synthesis has become imperative. We present a masking enone strategy that effectively suppresses side reactions associated with enone products, enabling the β-selective acylation of alkenes catalyzed by excited-state copper under sunlight or visible light. This reaction yields highly valuable α,β-unsaturated ketones, which can be readily transformed into important building blocks through various conversions. Notably, this method is characterized by its sustainable and eco-friendly energy source, mild reaction conditions, high compatibility with functional groups, and suitability for gram-scale synthesis, making it promising for late-stage modifications of complex molecules. Mechanistic studies indicate that the reaction proceeds via a free radical pathway.