Quinoid Carbene Mediated C(sp2)‐Heteroatom Bond Formation

C(sp2)‐heteroatom bonds play a critical role in biologically active molecules, pharmaceuticals, and functional materials. Traditional methods for synthesizing these bonds often rely on transition metal‐catalyzed cross‐coupling reactions, such as the Buchwald‐Hartwig and Ullmann reactions, which have limitations, including the requirement for elevated temperature and basic conditions. In recent years, diazo quinones have emerged as promising reagents for C(sp2)‐heteroatom bond formation due to their unique structural and reactive properties, which include high electrophilicity and a tendency toward aromatization. This review highlights recent advances in the use of quinoid carbenes, derived from diazo quinones, for the construction of C(sp2)‐N, C(sp2)‐O, and C(sp2)‐S bonds. Key methodologies discussed include rhodium‐, iridium‐, ruthenium‐ and palladium‐catalyzed cross‐coupling reactions, heteroatom‐H bond insertion reactions, migration reactions and sigmatropic rearrangements. These methods offer mild, functional group‐tolerant alternatives to traditional approaches, showcasing their utility in the synthesis of complex bioactive molecules, medicinally relevant compounds, and materials.