title: Mild and selective activation and substitution of strong aliphatic C-F bonds.
abstract: A procedure for chemoselectively manipulating the strong aliphatic C-F bond with direct transformation into a C-N bond under mild conditions is reported. The activation and subsequent substitution of primary alkyl fluorides is mediated by La[N(SiMe3)2]3, and results in high to excellent yields of tertiary amines. The methodology displays high selectivity towards the C(sp(3))-F bond, and a variety of secondary amines are applicable as nucleophiles. Mechanistic investigations reveal a reaction that is first order with respect to [La[N(SiMe3)2]3], [R(1)R(2)NH], and [alkyl fluoride], and a 6-membered cyclic transition state is proposed. In addition, (1)H NMR spectroscopy shows that La[N(SiMe3)2]3 is the active species involved in the substitution and that protonolysis of the amine, yielding La[NR(1)R(2)]3, lowers the reactivity.
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 41296, Gothenburg (Sweden).
authors.forename: Mario
authors.initials: M
authors.lastname: Janjetovic
authors.forename: Annika M
authors.initials: AM
authors.lastname: Träff
authors.forename: Göran
authors.initials: G
authors.lastname: Hilmersson
keywords: amines; chemoselectivity; fluorine; lanthanum; synthetic methods