Recent Advances in Cyclization Reactions of 1,6-Enynes

Elaborated molecular architectures, specifically those bearing one or more carbon stereocenters, stand as an important class of carbocyclic and heterocyclic frameworks because they are frequently occurring core structures in numerous natural products and biologically active pharmaceutical molecules. Over the past few decades, the development of versatile synthetic approaches via cascade cyclization reactions of 1,6-enynes for the construction of a series of fused and spiro compounds has been the focus of a great deal of research initiatives. These synthesis strategies are peculiarly fascinating in the context of the assembly of a wide array of pharmaceutical molecules, natural products, agrochemicals, and functional materials. In this review, recent developments in the transformations of 1,6-enynes with diverse coupling reagents are summarized since 2018, which could be divided into five categories: 1) Introduction; 2) Transition metal catalyzed cyclization of 1,6-enynes; 3) Metal-free cyclization of 1,6-enynes; 4) Visible-light-induced cyclization of 1,6-enynes; 5) Electrocatalytic cyclization of 1,6-enynes.