cs5001575_si_007.avi (4.61 MB)
Deconstructing Selectivity in the Gold-Promoted Cyclization of Alkynyl Benzothioamides to Six-Membered Mesoionic Carbene or Acyclic Carbene Complexes
media
posted on 2014-05-02, 00:00 authored by Sai Vikrama
Chaitanya Vummaleti, Laura Falivene, Albert Poater, Luigi CavalloWe
demonstrate that the experimentally observed switch in selectivity
from 5-exo-dig to 6-endo-dig cyclization of an alkynyl substrate,
promoted by AuI and AuIII complexes, is connected
to a switch from thermodynamic to kinetic reaction control. The AuIII center pushes alkyne coordination toward a single Au–C(alkyne)
σ-bond, conferring carbocationic character (and reactivity)
to the distal alkyne C atom.