Recent Advances in Transition‐Metal‐Catalyzed Cyclization Reactions of α‐Diazocarbonyl Compounds

α‐Diazocarbonyl compounds, as a class of versatile organic synthons, occupy a pivotal position in the field of organic chemistry. Their unique structural features endow them with rich reactivity, enabling decomposition under thermal, photolytic, or transition‐metal‐catalyzed conditions to generate highly reactive carbene or metal carbene intermediates, which subsequently participate in a variety of transformations. These reactions provide concise and atom‐economical synthetic strategies for the efficient construction of bioactive heterocyclic compounds, carbocyclic compounds, natural products, and pharmaceutical scaffolds. In recent years, with the rapid advancement of transition‐metal catalysis, remarkable progress has been achieved in cyclization reactions involving α‐diazocarbonyl compounds. Through precise control of catalysts and substrates, a diverse array of cyclization modes has been developed, ranging from simple [2 + 1] cyclopropanations to complex multicomponent cascade cyclizations such as [3 + 1 + 1] reactions, permitting diversity‐oriented synthesis. This review classifies the reactions according to different cycloaddition types (including [2 + 1], [2 + 2], [3 + 2], [3 + 3], [4 + 1], [4 + 2], [5 + 1], [5 + 2], [6 + 1], [3 + 1 + 1], and [4 + 1 + 1] cyclizations) and summarizes the recent advances in transition‐metal‐catalyzed cyclization reactions of α‐diazocarbonyl compounds over the past 5 years.