Recent advancement in copper-catalyzed asymmetric reactions of alkynes

Alkynes are among the most diverse functional groups with a great synthetic profile. In the presence of transition metal catalysts, an alkyne could be transformed into various functionalities such as alkanes, alkenes, carbonyls, allenes, carbocycles, and heterocycles, etc. Copper salts are inexpensive, stable, and extensively used catalysts for alkyne activation that happens either via sigma-bond or pi-bond complex formation. Sigma-bond complexation leads to nucleophilic alkyne species, whereas pi-bond complexation results in electrophilic alkyne species. Different domains of the copper-catalyzed reactions of alkynes have separately been reviewed by several research groups. This review covers the recent reports (2011–2020) on copper-catalyzed asymmetric reactions of alkynes, provides insight into the mode of catalysis, and discusses the evolution of alkyne-based organic transformations such as addition to carbonyls and imines, A3 coupling, allylic alkynylation, hydrofunctionalization, cycloaddition, click chemistry, Kinugasa reaction, and allene formation.