Interplay between the Directing Group and Multifunctional Acetate Ligand in Pd-Catalyzed <i>anti</i>-Acetoxylation of Unsymmetrical Dialkyl-Substituted Alkynes
Javier Corpas, Enrique M. Arpa, Romain Lapierre, Inés Corral, Pablo Mauleón, Ramón Goméz Arrayás, Juan C. Carretero
Abstract
-acetoxypalladation stereocontrol. Experimental and computational analyses provide insight into the reasons behind this delicate interplay between the ligand, directing group, and the metal in the reaction mechanism. In fact, these studies unveil the multiple important roles of the acetate ligand in the coordination sphere at the Pd center: (i) it brings the acetic acid reagent into close proximity to the metal to allow the simultaneous activation of the alkyne and the acetic acid, (ii) it serves as an inner-sphere base while enhancing the nucleophilicity of the acid, and (iii) it acts as an intramolecular acid to facilitate protodemetalation and regeneration of the catalyst. Further insight into the origin of the observed regiocontrol is provided by the mapping of potential energy profiles and distortion-interaction analysis.