Transition-Metal-Catalyzed Intramolecular Nucleophilic Addition of Carbonyl Groups to Alkynes

Summary Compounds consisting of a carbonyl group and an alkyne group, especially enynals and enynones, are versatile and powerful building blocks for generating structurally diverse polycyclic compounds. In the past decades, the transition-metal-catalyzed nucleophilic addition of a carbonyl group to an alkyne has attracted great interest for the high reactivity, good selectivity, excellent functional-group tolerance, and mild reaction conditions. Most importantly, versatile intermediates, such as pyrylium-ion, metal-carbene, 1,3-dipole, and metal-vinyl species, make it highly attractive for both the development of synthetic methodologies and applications in the synthesis of bioactive compounds or complex naturally occurring skeletons. This review focuses on the transition-metal-catalyzed nucleophilic addition of carbonyl groups to alkynes with an emphasis on the scope and limitations, the mechanisms, and applications in organic synthesis.