title: Dormant versus evolving aminopalladated intermediates: toward a unified mechanistic scenario in Pd(II)-catalyzed aminations.
abstract: Pd(II)-catalyzed alkene aminopalladation and allylic C-H activation are two competing reaction sequences sharing the same reaction conditions. This study aimed at understanding the factors that bias one or the other path in the intramolecular oxidative cyclization of two types of N-tosyl amidoalkenes. The results obtained are in accord with the initial generation of a high-energy cyclic (5- or 6-membered) aminopalladated intermediate. However, this latter species can evolve only if the following specific conditions are met: the availability of distocyclic β-H elimination pathway, the presence of a strong terminal oxidant, or the availability of a carbopalladation pathway. Conversely, the cyclic alkylpalladium complex is only a latent species in equilibrium with the initial substrate and cannot evolve. Such a reactivity hurdle leaves the way open for alternative reactivities such as allylic C-H activation of the olefinic substrate to generate a η(3)-allyl complex followed by its interception by the nitrogen nucleophile, [3,3]-sigmatropic rearrangement, or decomposition. This study proposes a unifying mechanistic picture that connects these competing mechanisms.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7201, Institut Parisien de Chimie Moléculaire, 75005 Paris (France), FR2769 Institut de Chimie Moléculaire; CNRS, UMR 7201, Institut Parisien de Chimie Moléculaire, 75005 Paris (France).
authors.forename: Jamshid
authors.initials: J
authors.lastname: Rajabi
authors.forename: Mélanie M
authors.initials: MM
authors.lastname: Lorion
authors.forename: Vu Linh
authors.initials: VL
authors.lastname: Ly
authors.forename: Frédéric
authors.initials: F
authors.lastname: Liron
authors.forename: Julie
authors.initials: J
authors.lastname: Oble
authors.forename: Guillaume
authors.initials: G
authors.lastname: Prestat
authors.forename: Giovanni
authors.initials: G
authors.lastname: Poli
keywords: CH activation; [3,3]-sigmatropic rearrangement; aminopalladation; beta-hydride elimination; palladium