Titre : Advances in α Elimination: Catalytic Organoelement Synthesis.
Endroit : Pavillon J.-A.-Bombardier, salle 1035 à 11 h
Hôte : Professeur Frank Schaper
La conférence sera prononcée (en anglais) par le professeur Rory Waterman, du Département de chimie de l'University of Vermont.
Résumé : After observation of α-arsinidene elimination from triamidoamine-supported zirconium complexes and reports of α-stannylene and -stibinidene elimination from group 4 metallocenes by Tilley, an expansion of the elements that participate in this rare class of deinsertion reactions has been sought. Triamidoamine supported zirconium complexes have been limited in effecting α elimination for lighter elements using, for example, silanes or phosphines as substrates. However, silanes with π-donating substituents, RXSiH2 (X = NMe2, Cl, etc), do react with [κ-N,N,N,N,C-(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH2]Zr (1) to give (N3N)ZrX (N3N = N(CH2CH2NSiMe3)33–) with evidence of silylene formation. Furthermore, catalytic N–Si dehydrocoupling using triamidoamine-supported zirconium complexes has provided an in situ substrate, RXSiH2, for α-silylene elimination. In select cases, the silylene fragment can be intercepted by an unsaturated organic substrate. Yet more success in organoelement synthesis has been realized recently with the use of iron catalysts. These compounds appear to dehydrocouple phosphines by α-phosphinidene elimination and can engage in catalytic preparation of phospholes from primary phosphines and either alkynes or dienes.
