Gold(I)‐Catalyzed Conia‐ene Cyclization of Internal <i>ϵ</i>‐Acetylenic β‐Ketoesters under High Pressure.

Abstract

Abstract The influence of pressure on the gold(I)‐catalyzed Conia‐ene cyclization of ϵ ‐acetylenic‐β‐ketoesters bearing an internal alkyne moiety was investigated for the first time. The reaction catalyzed by commercially available PPh 3 AuNTf 2 complex, which is sluggish at ambient pressure owing to steric reasons, proceeds smoothly under high‐pressure conditions (6 kbar). Mechanistic aspects of the reaction proceeding via 5 ‐ exo‐dig and 6 ‐ endo‐dig cyclization pathways were also studied employing DFT methods. Differences in the reactivity of substrates containing terminal and internal alkynes is discussed.