"Microwave-Assisted Synthesis of Hydroxymethyl Ketones Using Azolium-2-carboxylate Zwitterions as Catalyst Precursors"

Evanthia Papadaki, Lionel Delaude, and Victoria Magrioti

journal cover 
          source: Tetrahedron
            year: 2017
          volume: 73
      first page: 7295
       last page: 7300
             doi: 10.1016/j.tet.2017.11.024
graphical abstract

Abstract: Following an initial screening of six common imidazolium, imidazolinium, and dithiolium salts in the presence of a base, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IDip) and 1,3-dimesitylimidazolin-2-ylidene (SIMes) were identified as promising organocatalysts for the microwave-assisted synthesis of hydroxymethyl ketones from aldehydes and paraformaldehyde. The azolium-2-carboxylate zwitterions IDip·CO2 and SIMes·CO2 were then tested as single-component N-heterocyclic carbene (NHC) precursors in the hydroxymethylation of heptanal and benzaldehyde. The latter adduct was an efficient precatalyst for the two reactions. It was successfully applied to a broad range of aliphatic and aromatic substrates (14 examples, 10-97% yields).

Keywords: Green Chemistry, N-Heterocyclic Carbenes, Hydroxymethyl Ketones, Microwave Irradiation, Organocatalysis

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