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Green, Mild, and Efficient Friedel-Crafts Benzylation of Scarcely Reactive Arenes and Heteroarenes under On-Water Conditions.

Pellegrino La MannaAnnunziata SorienteMargherita De RosaAntonio BuonerbaCarmen TalottaCarmine GaetaPlacido Neri
Published in: ChemSusChem (2019)
Metal-free Friedel-Crafts benzylation (FCB) of scarcely reactive arenes and heteroarenes was performed under on-water conditions by an environmentally sustainable procedure. The catalytic strategy exploits the hydrophobicity of the resorcinarene macrocycle 1 a. The proposed mechanism is based on the activation of benzyl chloride by H-bonding interactions with catalyst 1 a. In fact, under on-water conditions the hydrophobic amplification of the strength of the H-bonding interactions between the OH groups of the resorcinarene catalyst and the chlorine atom of benzyl chloride leads to polarization of the C-Cl bond, which consequently promotes electrophilic attack of the π nucleophile. Thus, many arenes and heteroarenes were efficiently benzylated under mild on-water conditions by using resorcinarene 1 a as catalyst. The FCB of benzene is industrially relevant for the synthesis of diphenylmethane, and hence the on-water procedure was extended to the gram-scale synthesis of diphenylmethane, starting from benzene and benzyl chloride in the presence of resorcinarene catalyst 1 a.
Keyphrases
  • ionic liquid
  • room temperature
  • highly efficient
  • reduced graphene oxide
  • metal organic framework
  • visible light
  • drinking water
  • gram negative