Theoretical studies of 2,4,6-triarylpyridines, 1,8-dioxo-decahydroacridines and pyrido[2,3-d]-pyrimidine via an anomeric based oxidation

After introducing of anomeric effect (The Edward-Lemieux effect) by J.T. Edward in 1955 for the first time. Development of the topic of anomeric effect has a great attractive for chemists and biochemists [1]. A computational studies in the synthesis of 2,4,6-triarylpyridines, 1,8-dioxo-decahydroacridines and pyrido[2,3-d]-pyrimidine using Fe3O4@TiO2@O2PO2(CH2)2NHSO3H and [Fe3O4@SiO2] (CH2)3S-SO3H respectively as catalysts under solvent free conditions were occurred (Figure 1). The modeling and the appropriate calculations on the structures of the precursors, the transition states (TS) of the reactions, intermediates and the products have undertaken by DFT-B3LYP/6-31G* method [2]. The suggested anomeric based oxidation mechanism was supported by theoretical evidences. The theoretical study shows that the unpaired electron of the nitrogen atom within the 1,8-dioxo-decahydroacridines and pyrido[2,3-d]-pyrimid structures, showed favor resonance interaction toward electron withdrawing carbonyl groups. This phenomena do not allows the lone pair of the nitrogen atom to interact with the anti-bonding orbital of C-H bond in the 1,4- dihydropyridine moiety of 1,8-dioxo-decahydroacridine and pyrido[2,3-d]-pyrimidine. Therefore, the unaromatized 1,8- dioxo-decahydroacridines and pyrido[2,3-d]-pyrimid are the preferred structures than their corresponding aromatized products