title: Mechanistic Insights into the Post-Cyclization Isomerization in Gold-Catalyzed 7-exo-dig-Hydroarylations.
abstract: The subsequent double-bond isomerization in the synthesis of dibenzocycloheptenes and their heteroaromatic analogues was investigated. In the case of biphenyls, a basic additive completely prevented an isomerization to the thermodynamic product. With electron-rich intramolecular heteroaromatic nucleophiles, the isomerization was still observed, but the kinetic product can be obtained by careful control of the reaction times in most cases. Mechanistic studies demonstrated that a slow isomerization is also possible with the gold catalyst at elevated temperatures, but much faster isomerization rates were observed with acidic additives. An observed initiation period for the gold-catalyzed isomerization indicates that not the homogenous catalyst, but a decomposition product of it may be the catalytically active species.
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany).
authors.forename: Daniel
authors.initials: D
authors.lastname: Pflästerer
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany).
authors.forename: Sören
authors.initials: S
authors.lastname: Schumacher
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany).
authors.forename: Matthias
authors.initials: M
authors.lastname: Rudolph
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany). hashmi@hashmi.de.|Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia). hashmi@hashmi.de.
authors.forename: A Stephen K
authors.initials: AS
authors.lastname: Hashmi
keywords: additives; cycloheptenes; gold; hydroarylation; isomerization