We demonstrate that the experimentally observed switch in selectivity from 5-exo-dig to 6-endo-dig cyclization of an alkynyl substrate, promoted by Au-I and Au-III complexes, is connected to a switch from thermodynamic to kinetic reaction control. The Au-III center pushes alkyne coordination toward a single Au-C(alkyne) (sigma-bond, conferring carbocationic character (and reactivity) to the distal alkyne C atom.
Deconstructing Selectivity in the Gold-Promoted Cyclization of Alkynyl Benzothioamides to Six-Membered Mesoionic Carbene or Acyclic Carbene Complexes
Falivene, Laura;Cavallo, Luigi
2014
Abstract
We demonstrate that the experimentally observed switch in selectivity from 5-exo-dig to 6-endo-dig cyclization of an alkynyl substrate, promoted by Au-I and Au-III complexes, is connected to a switch from thermodynamic to kinetic reaction control. The Au-III center pushes alkyne coordination toward a single Au-C(alkyne) (sigma-bond, conferring carbocationic character (and reactivity) to the distal alkyne C atom.File in questo prodotto:
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