Photochemically Activated Dimagnesium(I) Compounds: Reagents for the Reduction and Selective C-H Bond Activation of Inert Arenes.

Photochemically Activated Dimagnesium(I) Compounds: Reagents for the Reduction and Selective C-H Bond Activation of Inert Arenes.
Angew Chem Int Ed Engl. 2021 Jan 20;:
Authors: Jones C, Jones DDL, Douair I, Maron L
Abstract
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.
PMID: 33474826 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - January 20, 2021 Category: Chemistry Authors: Jones C, Jones DDL, Douair I, Maron L Tags: Angew Chem Int Ed Engl Source Type: research