title: Polycationic ligands in gold catalysis: synthesis and applications of extremely π-acidic catalysts.
abstract: Very often ligands are anionic or neutral species. Cationic ones are rare, and, when used, the positively charged groups are normally appended to the periphery of the ligand. Here, we describe a dicationic phosphine with no spacer between the phosphorus atom and the two positively charged groups. This structural feature makes its donor ability poorer than that of phosphites and only comparable to extremely toxic or pyrophoric compounds such as PF3 or P(CF3)3. By exploiting these properties, a new Au catalyst has been developed displaying a dramatically enhanced capacity to activate π-systems. This has been used to synthesize very sterically hindered and naturally occurring 4,5-disubstituted phenanthrenes. The present approach is expected to be applicable to the development and improvement of many other transition metal catalyzed transformations that benefit from extremely strong π-acceptor ligands. The mechanism of selected catalytic transformations has been explored by density functional calculations.
authors.affiliation: Max-Planck-Institut für Kohlenforschung , Kaiser Wilhelm Platz 1, Mülheim an der Ruhr, 45470, Germany.
authors.forename: Javier
authors.initials: J
authors.lastname: Carreras
authors.forename: Gopinadhanpillai
authors.initials: G
authors.lastname: Gopakumar
authors.forename: Lianghu
authors.initials: L
authors.lastname: Gu
authors.forename: Liangu
authors.initials: L
authors.lastname: Gu
authors.forename: Ana
authors.initials: A
authors.lastname: Gimeno
authors.forename: Pawel
authors.initials: P
authors.lastname: Linowski
authors.forename: Jekaterina
authors.initials: J
authors.lastname: Petuškova
authors.forename: Walter
authors.initials: W
authors.lastname: Thiel
authors.forename: Manuel
authors.initials: M
authors.lastname: Alcarazo