Mechanistic insight into the ruthenium-catalyzed cycloaddition of enynes with alkynes: A theoretical study

Abstract

The density functional theory (DFT) has been employed to elucidate the mechanisms of ruthenium-catalyzed cycloaddition of enynes with alkynes. The calculated results suggest that there are similar reaction pathways for symmetrical and nonsymmetrical alkynes, including oxidative cyclization, insertion of the alkynes, and reductive elimination, respectively. The oxidative cyclization is calculated to be the rate-determining step. The regioselectivity-determining step for this reaction is the alkyne insertion and the observed regioselectivity could be interpreted through the HOMO coefficient analysis.