Interplay between the Directing Group and Multifunctional Acetate Ligand in Pd-Catalyzed -Acetoxylation of Unsymmetrical Dialkyl-Substituted Alkynes.

The cooperative action of the acetate ligand, the 2-pyridyl sulfonyl (SOPy) directing group on the alkyne substrate, and the palladium catalyst has been shown to be crucial for controlling reactivity, regioselectivity, and stereoselectivity in the acetoxylation of unsymmetrical internal alkynes under mild reaction conditions. The corresponding alkenyl acetates were obtained in good yields with complete levels of β-regioselectivity and -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.