Direct 1,2‐Dicarbonylation of Alkenes towards 1,4‐Diketones via Photocatalysis.

1,4‐Dicarbonyl compounds are intriguing motifs and versatile precursors in numerous pharmaceutical molecules and bioactive natural compounds. Direct incorporation of two carbonyl groups into a double bond at both ends is straightforward, but also challenging. Represented herein is the first example of 1,2‐dicarbonylation of alkenes by photocatalysis. Key to success is that N(n‐Bu)4+ not only associates with the alkyl anion to avoid protonation, but also activates the α‐keto acid to undergo electrophilic addition. The α‐keto acid is employed both for acyl generation and electrophilic addition. By tuning the reductive and electrophilic ability of the acyl precursor, unsymmetric 1,4‐dicarbonylation is achieved for the first time. This metal‐free, redox‐neutral and regioselective 1,2‐dicarbonylation of alkenes is executed by a photocatalyst for versatile substrates under extremely mild conditions and shows great potential in biomolecular and drug molecular derivatization. [ABSTRACT FROM AUTHOR]