Theoretical Study of the Mechanism of Palladium(0)‐Catalyzed Intramolecular [2+2+2] Cycloaddition of Ester‐Substituted Alkynes

Abstract

The mechanisms of the palladium(0)‐catalyzed cross [2+2+2] cycloaddition of a diyne diester with dimethyl acetylenedicarboxylate and of the [2+2+2] cyclization of a triyne diester were investigated using density functional theory calculations. After evaluating the kinetic and thermodynamic profiles of each reaction, the roles of the ester substituents on the alkyne substrates and of the triphenylphosphine ligand are discussed based on the obtained results. Moreover, the previously unreported cross [2+2+2] cycloaddition of the diyne diester with nitriles was also investigated, in order to evaluate its feasibility under the relevant experimental conditions.