Spectroscopic and computational evidence for the concerted mechanism of the Wagner‐Jauregg reaction

The Wagner‐Jauregg reaction, despite its potential utility, has remained largely unexplored since its discovery in 1930. Utilizing density functional theory (DFT) calculations and experimental 1H nuclear magnetic resonance (NMR) kinetics data to generate a Hammett plot, the reaction is shown to proceed via a highly asynchronous, concerted mechanism, analogous to the Diels–Alder reaction. Our development of milder, more reliable reaction conditions for the Wagner‐Jauregg reaction will facilitate the synthesis of novel, structurally complex, polycyclic molecules.