An efficient synthesis of novel triazoles incorporating barbituric motifs via [3+2] cycloaddition reaction: An experimental and theoretical study

In this work, the synthesis of novel triazole derivatives with barbituric motifs in good yields is described. The alkyne was prepared through the Knoevenagel reaction of barbituric derivatives with ortho and para O-propargylated hydroxybenzaldehyde. The mechanism and regioselectivity of this [3+2] cycloaddition reaction were investigated using the density functional theory at the B3LYP/6-31+G(d) level of theory. The computational studies revealed that a di-copper catalyzed stepwise mechanism, involving six-membered ring intermediate, is the preferred pathway. The regioselectivity was explained in terms of frontier molecular orbital (FMO) interactions, local and global electrophilicity and nucleophilicity indices. Accordingly, the favored interactions for di-copper acetylide are in good agreement with the observed regioselectivity, while completely opposite results were obtained for a possible uncatalysed reaction

Preparation of magnetic chitosan- graphene oxide-MnFe2O4 nanocomposite and its application for removal of naphthol blue black (NBB)

In this study, a novel chitosan, graphene oxide and MnFe2O4 composite (CS-GO-MnFe2O4) was prepared as a magnetic bioadsorbent for water purification. The morphology, chemical structure and magnetic property of the composite were characterized by FT-IR, XRD, SEM and VSM analysis. The resulting composite shows good adsorption capacity for removal of naphthol blue black (NBB) as an acid dye model, in water. Adsorption of NBB onto CS-GO-MnFe2O4 was investigated with respect to pH, adsorption time, initial NBB concentration and temperature. The study of the adsorption isotherms and kinetics at the optimum pH 6.0, revealed that the pseudo-second-order kinetic and Langmuir isotherm model well-described kinetics and equilibrium adsorptions, respectively. The values of thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption process is spontaneous and exothermic in nature. The results show that, more than 80% color removal could be achieved in 60 min contact time with 40 mg L−1 of initial concentrations

A Facile Regioselective Synthesis of Novel Spiroacenaphthene Pyrroloisoquinolines Through 1,3-Dipolar Cycloaddition Reactions

An efficient one-pot three-component procedure for the synthesis of novel spiroacenaphthene pyrroloisoquinolines with high regioselectivity is described. These compounds were prepared from 1,3-dipolar cycloaddition of an azomethine ylide generated from acenaphthenequinone and 1,2,3,4-tetrahydroisoquinoline via [1,5]-H shift, with chalcone and nitrostyrene derivatives as dipolarophiles. The structure and stereochemistry of the cycloadducts have been established by single crystal X-ray structure and spectroscopic techniques

A theoretical investigation on the regioselectivity of the intramolecular hetero Diels-Alder and 1,3-dipolar cycloaddition of 2-vinyloxybenzaldehyde derivatives

The present study reports a systematic computational analysis of the two possible pathways, fused and bridged, for an intramolecular hetero Diels-Alder (IMHDA) and an intramolecular 1,3-dipolar cycloaddition (IMDCA) of 2-vinyloxybenzaldehyde derivatives. The potential energy surface analysis for both reactions is in agreement with experimental observations. The activation energies associated with the two regioisomeric channels in IMHDA reaction show that the bridged product is favored, although in IMDCA, the most stable TS results the fused product. The global electronic properties of fragments within each molecule were studied to discuss the reactivity patterns and charge transfer direction in the intramolecular processes. The asynchronicity of the bond formation and aromaticity of the optimized TSs in the Diels-Alder reaction as well as cycloaddition reaction were evaluated. Finally, 1H NMR chemical shifts of the possible regioisomers have been calculated using the GIAO method which of the most stable products are in agreement with the experimental data in the both reaction