| Popis: |
Direct C–H arylation of unactivated benzene with aryl halides under various simple ligands (EDA, DMEDA, ethylene glycol, etc.) in the presence of potassium tert -amylate ( t -AmOK) base at mild temperature (80 °C) have been developed. This transition-metal-free radical cross-coupling offers an efficient way to synthesize various biaryls in good yields through base-promoted homolytic aromatic substitution. And mechanistic investigations have provided insight into the chemoselectivity of couplings between haloiodobenzenes and benzene and showed that phenanthroline and its derivatives not only initiate these radical reactions like most of other ligands (EDA, DMEDA, ethylene glycol, etc.), but also participate in the electron transfer process of biaryl radical anion intermediates. |
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