Mankad Neal P, Toste F Dean
Department of Chemistry, University of California-Berkeley, Berkeley, CA, 94720, USA.
Chem Sci. 2012 Jan 1;3(1):72-76. doi: 10.1039/C1SC00515D. Epub 2011 Oct 13.
Rare examples of C(sp(3))-F reductive elimination were observed from several cis-F(2)Au(R)(IPr) intermediates generated by oxidation of (IPr)AuR complexes with XeF(2). For R groups bearing β-hydrogens, β-hydride elimination was competitive with C(sp(3))-F reductive elimination. For strained cyclic R groups and most acyclic R groups lacking β-hydrogens, carbocation-like rearrangements occurred prior to C(sp(3))-F reductive elimination. Kinetics of the decay of one cis-F(2)Au(R)(IPr) species, stereochemical analysis of reductive elimination with a chiral R group, and DFT analysis collectively suggest C(sp(3))-F reductive elimination proceeding through transient cationic (IPr)Au(F)(R) intermediates with significant ionization of the Au-alkyl bonds.
通过用XeF₂氧化(IPr)AuR配合物生成的几种顺式-F₂Au(R)(IPr)中间体中,观察到了罕见的C(sp(3))-F还原消除实例。对于带有β-氢的R基团,β-氢消除与C(sp(3))-F还原消除相互竞争。对于张力环状R基团和大多数缺乏β-氢的无环R基团,在C(sp(3))-F还原消除之前会发生类碳正离子重排。一种顺式-F₂Au(R)(IPr)物种衰变的动力学、用手性R基团进行还原消除的立体化学分析以及DFT分析共同表明,C(sp(3))-F还原消除是通过瞬态阳离子[(IPr)Au(F)(R)]⁺中间体进行的,且金-烷基键有显著的离子化。