All elementary steps in the mechanism of Pd-catalyzed decarbonylation of hydrocinnamic acid through formation of a mixed anhydride species have been characterized through electronic structure calculations. Oxidative addition of the mixed anhydride to a singly or doubly ligated Pd is followed by decarbonylation, alkene formation, and catalyst regeneration. Metal-assisted deprotonation of the alkyl-Pd species by a coordinated carboxylate is predicted to be the rate-determining step; theory suggests that bulkier phosphine ligands (e.g., P(o-Tol)3) reduce the free energy of activation substantially, while variation of the auxiliary anhydride has little influence on efficiency.
Bibliographical noteFunding Information:
This research was supported by the National Science Foundation (NSF) through the Center for Sustainable Polymers (CHE-1413862). The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing resources that contributed to the research results reported within this paper.
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