title: Role of the base in Buchwald-Hartwig amination.
abstract: The Buchwald-Hartwig amination has been investigated theoretically and experimentally to examine the scope of possible bases under different reaction conditions. Nonpolar solvents resist the formation of new charges. Therefore, the base should be anionic to be able to deprotonate the neutral palladium-amine complex and/or expel the anionic leaving group (bromide). The calculated barrier for the organic base DBU was found to be prohibitively high. In polar solvent, dissociation of bromide becomes possible, but here the base will instead form a complex with palladium, creating an overly stable resting state. The conclusions for both solvent classes hold for both a hindered monodentate phosphine and the labile bidentate ligand BINAP. The computational studies were supported by experimental testing of a range of bases using BINAP in two different solvents, toluene and DMF.
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg , Kemigården 4, SE-412 96 Göteborg, Sweden.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Sunesson
authors.forename: Elaine
authors.initials: E
authors.lastname: Limé
authors.forename: Sten O
authors.initials: SO
authors.lastname: Nilsson Lill
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Meadows
authors.forename: Per-Ola
authors.initials: PO
authors.lastname: Norrby
mesh_terms: D000586:Amination; D002384:Catalysis; D008958:Models, Molecular; D009281:Naphthalenes / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry; D012997:Solvents; D014050:Toluene / Q000737:chemistry*
chemical_list: C406943:BINAP, 2-naphthol; D009281:Naphthalenes; D012997:Solvents; D014050:Toluene; D010165:Palladium