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Photochemically Activated Dimagnesium(I) Compounds: Reagents for the Reduction and Selective C−H Bond Activation of Inert Arenes
Author(s) -
Jones Dafydd D. L.,
Douair Iskander,
Maron Laurent,
Jones Cameron
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202017126
Subject(s) - chemistry , benzene , toluene , photochemistry , fluorobenzene , radical , medicinal chemistry , biphenyl , reagent , benzophenone , organic chemistry
The photochemical activation of dimagnesium(I) compounds, and subsequent high yielding, regioselective reactions with inert arenes are reported. Irradiating benzene solutions of [{( Ar Nacnac)Mg} 2 ] ( Ar Nacnac=[HC(MeCNAr) 2 ] − ; 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, [{( Ar Nacnac)Mg} 2 (μ‐C 6 H 6 )]. Irradiation of [{( Dip Nacnac)Mg} 2 ] in toluene, and each of the three isomers of xylene, promoted completely regio‐ and chemo‐selective C−H bond activations, and formation of [( Dip Nacnac)Mg(Ar′)] (Ar′= meta ‐tolyl; 2,3‐, 3,5‐ or 2,5‐dimethylphenyl), and [{( Dip Nacnac)Mg(μ‐H)} 2 ]. Fluorobenzene was cleanly defluorinated by photoactivated [{( Dip Nacnac)Mg} 2 ], leading to biphenyl and [{( Dip Nacnac)Mg(μ‐F)} 2 ]. 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.