CO-Free Aminocarbonylation of Terminal Alkynes Catalyzed by Synergistic Effect From Metal-Organic Frameworks.

Incorporation of CO into substrates to construct high-value carbonyl compounds is an intensive industrial carbonylation procedure, however, high toxicity and wide explosion limits (12.5-74.0 vol% in air) of CO limit its application in industrial production. The development of a CO-free catalytic system for carbonylation is one of ideal methods, but full of challenge. Herein, this study reports the CO-free aminocarbonylation conversion of terminal alkynes synergistically catalyzed by a unique Co(ІІ)/Ag(І) metal-organic framework (MOF), in which the combination of isocyanides and O is employed as safe and green source of aminocarbonyl. This reaction has broad substrate applicability in terminal alkyne and isocyanides components with 100% atom economy. The bimetal MOF catalyst can be recycled at least five times without substantial loss of catalytic activities. Mechanistic investigations demonstrate that the synergistic effect between Ag(I) and Co(II) sites can efficiently activate terminal alkyne and isocyanides, respectively. Free radical capture experiments, FT-IR analysis and theoretical explorations further reveal that terminal alkynes and isocyanides can be catalytically transformed into an anionic intermediate through heterolysis pathways. This work provides secure and practical access to carbonylation as well as a new approach to aminocarbonylation of terminal alkynes.