The tandem reactions of metal carbenes with alkynes represent a powerful strategy for constructing structurally diverse and complex organic molecules. Among these, the "carbene migration" strategy—wherein a metal carbene undergoes intramolecular or intermolecular migration in the presence of an alkyne to generate a new reactive carbene intermediate—has attracted significant attention in recent years. This migratory process typically proceeds via three distinct pathways: the carbene-alkyne metathesis (CAM)-like pathway, the metal migration pathway involving alkenyl cation intermediates, and the migration mediated by the formation and subsequent ring-opening of cyclopropene intermediates. The newly generated carbene intermediates are subsequently quenched through classical pathways such as C—H insertion, cyclization, or small molecule insertion, thereby enabling efficient cascade cyclization and functionalization. Although conventional carbene-alkyne metathesis has been occasionally reviewed, the rapid evolution of carbene migration strategies has recently unlocked unique synthetic opportunities, particularly in the indirect access to highly reactive carbenes, the assembly of sophisticated polycyclic systems, and the construction of complex material molecular skeletons via iterative migrations. This review comprehensively summarizes the advances over the past decade in cascade cyclization-functionalization reactions centered on carbene migration mechanisms. We deeply discuss the reaction mechanisms, structure-activity relationships, and synthetic applications under various catalytic systems, aiming to provide inspiring insights for the future development of novel carbene transformations and their expanded utility in functional material synthesis.

Key words: metal carbenes, alkynes, cyclization reactions, C—C bond formation