A Reaction Mechanism for Gold-Catalyzed Hydroamination/Cyclization of <i>o</i>‑Phenylendiamine and Propargylic Alcohols. A DFT Study

The atom-economic gold-catalyzed reaction of o-phenylendiamine and propargylic alcohols was investigated theoretically and computationally. A reaction mechanism was proposed with reasonable energetics. The Au­(I)-induced coupling of the two substrates allows for the formation of a C–N bond, from which the reaction initiates the dehydration by using the hydroxyl and the proton from the NH2+ moiety. Then cyclization is followed to give a seven-membered ring species. Subsequently, 1,3-proton transfer, Au–C bond cleavage, C–H bond formation, and deprotonation evolve into the product.