2,3‐Dichloro‐5,6‐Dicyano‐1,4‐Benzoquinone (DDQ)‐Mediated CC Bond Formation: Redox Strategies from Stoichiometric to Catalytic Systems

2,3‐Dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) has long been recognized as a versatile organic oxidant that mediates diverse transformations through single‐electron transfer, hydride abstraction, and redox cycling. Beyond its classical stoichiometric role in oxidation and dehydrogenation, DDQ now serves as an efficient catalyst for carbon–carbon bond formation across thermal, photochemical, and electrochemical domains. In stoichiometric reactions, DDQ enables benzylic and allylic CH activation to generate oxocarbenium or iminium intermediates that couple with a broad range of nucleophiles, facilitating alkylation, arylation, cyanation, and annulation processes. In catalytic systems, DDQ participates in redox cycles where the DDQ/DDQH 2 couple is regenerated by oxidants such as O 2 , nitrites, or MnO 2 , offering mild and simple access to complex carbon frameworks. The scope further extends to asymmetric catalysis and radical‐mediated cross‐dehydrogenative coupling, providing sustainable routes to natural product‐like scaffolds and biologically active molecules. This review highlights the progression of DDQ from a stoichiometric oxidant to a redox‐active catalyst, emphasizing its growing utility in controlled, metal‐free oxidative CC bond formation and its promise for next‐generation sustainable synthesis.