title: Mechanistic insights into enantioselective gold-catalyzed allylation of indoles with alcohols: the counterion effect.
abstract: Enantioselective gold-catalysis is emerging as a powerful tool in organic synthesis for the stereoselective manipulation of unfunctionalized unsaturated hydrocarbons. Despite the exponential growth, the molecular complexity of common chiral gold complexes generally prevents a complete description of the mechanism steps and activation modes being documented. In this study, we present the results of a combined experimental-computational (DFT) investigation of the mechanism of the enantioselective gold-catalyzed allylic alkylation of indoles with alcohols. A stepwise S(N)2'-process (i.e. anti-auroindolination of the olefin, proton-transfer, and subsequent anti-elimination [Au]-OH) is disclosed, leading to a library of tricyclic-fused indole derivatives. The pivotal role played by the gold counterion, in terms of molecular arrangement (i.e. "folding effect") and proton-shuttling in restoring the catalytic species, is finally documented.
authors.affiliation: Dipartimento di Chimica G. Ciamician, Alma Mater Studiorum-Università di Bologna, via Selmi 2, 40126 Bologna, Italy. marco.bandini@unibo.it
authors.forename: Marco
authors.initials: M
authors.lastname: Bandini
authors.forename: Andrea
authors.initials: A
authors.lastname: Bottoni
authors.forename: Michel
authors.initials: M
authors.lastname: Chiarucci
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Cera
authors.forename: Gian Pietro
authors.initials: GP
authors.lastname: Miscione