Insights into the C[sbnd]H activation mechanism in the Rh(I)-Catalyzed alkenylation of ketone with alkyne.

[Display omitted] The mechanisms of the Rh(I)-catalyzed alkenylation reaction were investigated by density functional theory (DFT) calculations. Our results show that the C H activation of this reaction occurs through the metal hydride pathway rather than the general concerted metalation deprotonation (CMD) mechanism. The favorable metal–hydride pathway involves C H oxidative addition, alkyne migratory insertion into Rh H and C C reductive elimination. Moreover, the consecutive migratory insertion into the Rh H and C C reductive elimination is kinetically more favorable than the alkyne migratory insertion into Rh C and C H reductive elimination. The CMD pathway is kinetically unfavorable due to the considerably higher barrier of several elementary steps. The improved mechanistic understanding will enable design of novel couplings between hydrocarbons and C H bonds. [ABSTRACT FROM AUTHOR]