DFT-Based Mechanism for the Unexpected Formation of Dienes in the PtCl₂ Isomerization of Propargylic Acetates:  Examples of Inhibition of the Rautenstrauch Process

The reactivity of the Pt(II)-mediated processes of unsaturated compounds strongly depends on the substrate structure, and the catalytic activation process may follow different reaction paths, such as skeletal rearrangements, cyclizations, and isomerizations. Herein, we analyze and report the striking effect of an ester group as an alkyne substituent on the reactivity of propargylic enynes, which has been shown to inhibit the expected Rautenstrauch process. The computed results agree with experimental evidence and provide a comprehensible rationalization.