Jones Dafydd D L, Douair Iskander, Maron Laurent, Jones Cameron
School of Chemistry, Monash University, PO Box 23, Clayton, VIC, 3800, Australia.
Université de Toulouse et CNRS, INSA, UPS, UMR 5215, LPCNO, 135 Avenue de Rangueil, 31077, Toulouse, France.
Angew Chem Int Ed Engl. 2021 Mar 22;60(13):7087-7092. doi: 10.1002/anie.202017126. Epub 2021 Feb 24.
The photochemical activation of dimagnesium(I) compounds, and subsequent high yielding, regioselective reactions with inert arenes are reported. Irradiating benzene solutions of [{( Nacnac)Mg} ] ( Nacnac=[HC(MeCNAr) ] ; Ar=2,6-diisopropylphenyl (Dip) or 2,4,6-tricyclohexylphenyl (TCHP)) with blue or UV light, leads to double reduction of benzene and formation of the "Birch-like" cyclohexadienediyl bridged compounds, [{( Nacnac)Mg} (μ-C H )]. Irradiation of [{( Nacnac)Mg} ] in toluene, and each of the three isomers of xylene, promoted completely regio- and chemo-selective C-H bond activations, and formation of [( Nacnac)Mg(Ar')] (Ar'=meta-tolyl; 2,3-, 3,5- or 2,5-dimethylphenyl), and [{( Nacnac)Mg(μ-H)} ]. Fluorobenzene was cleanly defluorinated by photoactivated [{( Nacnac)Mg} ], leading to biphenyl and [{( Nacnac)Mg(μ-F)} ]. Computational studies suggest all reactions proceed via photochemically generated magnesium(I) radicals, which reduce the arene substrate, before C-H or C-F bond activation processes occur.
报道了二价镁（I）化合物的光化学活化以及随后与惰性芳烃发生的高产率、区域选择性反应。用蓝光或紫外光照射[{(Nacnac)Mg}]（Nacnac = [HC(MeCNAr)]；Ar = 2,6 - 二异丙基苯基（Dip）或2,4,6 - 三环己基苯基（TCHP））的苯溶液，会导致苯的双还原并形成“类Birch”环己二烯二基桥联化合物[{(Nacnac)Mg}(μ - C₆H₆)]。在甲苯以及二甲苯的三种异构体中照射[{(Nacnac)Mg}]，促进了完全区域和化学选择性的C - H键活化，并形成[(Nacnac)Mg(Ar')]（Ar' = 间甲苯基；2,3 -、3,5 - 或2,5 - 二甲基苯基）和[{(Nacnac)Mg(μ - H)}]。光活化的[{(Nacnac)Mg}]能使氟苯干净地脱氟，生成联苯和[{(Nacnac)Mg(μ - F)}]。计算研究表明，所有反应均通过光化学产生的镁（I）自由基进行，这些自由基在C - H或C - F键活化过程发生之前还原芳烃底物。
