Aza Chalcone Synthesis And The Michael Addition Reaction

Chalcones have become a kind of important intermediates in organic synthesis. Based on the propertities of chalcones, a serials of reactions, such as Michael addition, photocycloaddition, polymerization etc are normally involved and chalcones are also widely used in coordination chemistry and supramolecular chemistry. Some chalcones and their analogues showed excellent biological activities, for example: antibacterial, antiviral, antifungal, antitumor activities and inhibiting the growth of weed. The synthesis and isolation of chalcones from natural products have drawn much attention in the field of biomedical, agronomy, and food science. As a kind of versatile intermediates, chalcones have been used widely in the synthesis of organic compounds and medicines. Among them, Michael addition reaction is one of the typical reactions.There are extensive works on chalcones and azachalcones has been reported. However, there are very few reports on azachalcones, especially the azachalcones with two pyridyl rings. In the present work, the synthesis of azachalcones and its Michael addition reactions were investigated. Pyrimidines, 3-hydroxycyclohexanones, cyclohex-2-enones and terpyri-dine were prepared through Michael addition and subsequent cyclocondensation (some compounds undergo aromatization at the same time). Moreover, the reaction conditions were optimized and the related mechanisms were discussed. The main results are listed as follows:1. According to the literatures, seven azachalcones were prepared. The yields of azachalcones were increased by optimization of reaction conditions from reported 40% to 70%.2. A range of 2-aminopyrimidines were synthesized by the reactions of azachalcones and guanidine under basic conditions and an important intermediate was successfully obtained. The redox of 4,6-dipyridinyl-2-aminopyrimidine and 4-phenyl-6-pyridinyl-2-aminopyrimidine were investigated by cyclic voltammetry.3. A range of 5-bromo-2-amino-pyrimidines were synthesized from theabove mentioned 2-aminopyrimidines with bromine in high yield (98%).4. The Micheal additions of azachalcones with active methylene/methyl compounds were investigated. Different products such as 3-hydroxycyclo-hexanones or cyclohex-2-enones were obtained under varied conditions.5. A range of terpyridine were synthesized from the reaction of azachalcones with malonamide followed by an aromatization.Potential application of azachalcones is prospected based on the present work and the related references.33 new compounds were reported in the present work. All the compounds were characterized by IR and H NMR.