Solvent-Free Synthesis of N-aryl-b-Enaminones Under Microwave Irradiation

2014 Asian Journal of Chemistry  
β-Enaminone compounds are very important intermediates for organic synthesis and have received considerable attentions in recent years, which can be used for the synthesis of some compounds having biological or pharmacological activity, such as αor β-amino acids, polypeptide, alkaloid, pyrazole, etc. 1-3 . β-Enaminone with aryl group on N-atom, i.e. N-aryl-βenaminone, can also chelate with transition metals to obtain complexes, which can usually be used for the catalysts of olefin
more » ... or oligomerization 4 . Traditionally, β-enaminone compounds can be prepared by the condensation of β-diketones with amines catalyzed by proton acid catalysts 5,6 , which usually needs organic solvents and high temperature to reflux and remove the generated water. These methods would lead to low yield, complicated after-treatment, high energy consumption and serious environmental pollution, etc. Better results can be obtained when solid Lewis acid catalysts 7-9 were used, but the yields for N-aryl-βenaminones are much lower. Microwave has been widely adopted for the synthesis of organic compounds. Since the mid-1980s, a large number of studies have demonstrated that an acceleration of chemical rates can be achieved by employing high-density microwave irradiation instead of traditional sources of heat. Recently we synthesized a series of N-aryl-β-enaminones in good yields without any supernumerary solvents under microwave irradiation, which was followed as Scheme-I.
doi:10.14233/ajchem.2014.15524 fatcat:mn5rkebu7jfatco2hyaeptdmhm