title: Constructing a Catalytic Cycle for C-F to C-X (X = O, S, N) Bond Transformation Based on Gold-Mediated Ligand Nucleophilic Attack.
abstract: A tricoordinated gold(I) chloride complex, tBuXantphosAuCl, supported by a sterically bulky 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)xanthene ligand (tBuXantphos) was synthesized. This complex features a remarkably longer Au-Cl bond length [2.632(1) Å] than bicoordinated linear gold complexes (2.27-2.30 Å) and tricoordinated XantphosAuCl [2.462(1) Å]. Single-crystal X-ray diffraction analysis of a cocrystal of tBuXantphosAuCl and pentafluoronitrobenzene (PFNB) and UV-vis spectroscopic titration experiments revealed the existence of an anion-π interaction between the Cl anion ligand and PFNB. Stoichiometric reaction between PFNB and tBuXantphosAuOtBu, after replacement of Cl by a more nucleophilic tBuO anion ligand, showed higher reactivity and para selectivity in the transformation of C-F to C-OtBu bond, distinctively different from that when only KOtBu was used (ortho selectivity) under the identical condition. Mechanistic studies including density functional theory calculations suggested a gold-mediated nucleophilic ligand attack of the C-F bond pathway via an SNAr process. On the basis of these results, using trimethylsilyl derivatives TMS-X (X = OMe, SEt, NEt2) as the nucleophilic ligand source and the fluorine acceptor, catalytic transformation of the C-F bond of aromatic substrates to the C-X (X = O, S, N) bond was achieved with tBuXantphosAuCl as the catalyst (up to 20 turnover numbers).
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China.
authors.forename: Ji-Yun
authors.initials: JY
authors.lastname: Hu
authors.affiliation: College of Materials Science and Optoelectronics Technology, Graduate University of Chinese Academy of Sciences , Beijing 100049, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China.
authors.forename: Gao-Xiang
authors.initials: GX
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Beijing Key Laboratory of Energy Conversion and Storage Materials, Beijing Normal University , Beijing 100875, P. R. China.
authors.forename: Hao-Ling
authors.initials: HL
authors.lastname: Sun
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China.
authors.forename: Jun-Long
authors.initials: JL
authors.lastname: Zhang