Catalytic Role of Nickel in the Decarbonylative Addition of Phthalimides to Alkynes

Density functional theory calculations have been used to investigate the catalytic role of nickel(0) in the decarbonylative addition of phthalimides to alkynes. According to Kurahashi et al. the plausible reaction mechanism involves a nucleophilic attack of nickel at an imide group, giving a six-membered metallacycle, followed by a decarbonylation and insertion of an alkyne leading to a seven-membered metallacycle. Finally a reductive elimination process produces the desired product and regenerates the nickel(0) catalyst. In this paper, we present a full description of the complete reaction pathway along with possible alternative pathways, which are predicted to display higher upper barriers. Our computational results substantially confirm the proposed mechanism, offering a detailed geometrical and energetical understanding of all the elementary steps.