Novel Synthetic Strategies and Mechanistic Insights Into the Tandem Cyclization of 1,5‐Enynes

1,5‐enynes, characterized by the dual reactivity of alkene and alkyne groups, stand out as indispensable synthons in organic synthesis and are capable of efficiently assembling five‐membered, six‐membered, fused‐ring, and spirocyclic skeletons via intramolecular cascade cyclization. As these cyclic architectures widely exist as key structural units in numerous natural products and pharmacologically relevant compounds, the development of efficient, selective 1,5‐enyne cyclization strategies carries profound theoretical implications and practical utility. Over the past few decades, considerable progress has been made in the rational design of catalytic systems, in‐depth mechanistic studies, and practical synthetic implementations of 1,5‐enyne cyclization, displaying far‐reaching potential in the construction of drug libraries, total synthesis of natural products, and development of functional molecules. In this review, the cutting‐edge developments enabling the facile construction of structurally diverse and elaborate molecular skeletons through 1,5‐enyne cyclization are systematically summarized, which can be primarily categorized into the following five categories: (1) metal‐catalyzed cyclization of 1,5‐enynes; (2) metal‐free catalyzed cyclization of 1,5‐enynes; (3) visible‐light‐induced cyclization of 1,5‐enynes; (4) microwave‐assisted cyclization of 1,5‐enynes; and (5) electrocatalytic cyclization of 1,5‐enynes.