Rapid formation of chemical complexity via a modified Biginelli reaction leading to dihydrofuran-2(3 H )-one spiro-derivatives of triazolo[1,5- a ]pyrimidine

A facile hydrothermal synthesis of high-efficient NiO nanocatalyst for preparation of 3,4-dihydropyrimidin-2(1H)-ones

The present work introduces a one-step and facile hydrothermal procedure as a green process for the first time to synthesize nickel(II) oxide (NiO) nanoparticles. The as-prepared nanomaterials were used as high efficient, low toxic and cost catalyst for the synthesis of some organic compounds. Ni(NO₃)₂ and some natural extract were used as a surfactant for the first time to synthesis NiO nanomaterials. A high synthesis yield (91%) was obtained for S₂. Rietveld analysis affirmed the cubic crystal system of the obtained NiO nanocatalyst. The morphology studies were carried out with the FESEM method and the images revealed a change from non-homogenous to homogenous spherical particles when the Barberryas was used instead of orange blossom surfactant. Besides, the images revealed that the particle size distribution was in the range of 20 to 60 nm. The synthesized catalysts were used for the first time in Biginelli multicomponent reactions (MCRs) for the preparation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) under the present facile reaction conditions. High yield (97%) of the final product was achieved at the optimum condensation reaction conditions (Catalyst: 60 mg; temperature: 90 °C and time: 90 min) when ethyl acetoacetate/methyl acetoacetate (1 mmol), benzaldehyde (1 mmol) and urea (1.2 mmol) were used. A kinetic study affirmed pseudo-first-order model for Biginelli reactions followed the pseudo-first-order model.

The first coordination complex of (5R,6R,7S)-5-(furan-2-yl)-7-phenyl-4,5,6,7-tetrahydro-[1,2,4]triazolo[1,5-a]pyrimidin-6-amine with zinc(II) acetate-chloride

The first coordination complex with (5R,6R,7S)-5-(furan-2-yl)-7-phenyl-4,5,6,7-tetra­hydro-[1,2,4]triazolo[1,5-α]pyrimidin-6-amino as a bridged ligand coordinating two zinc atoms has been synthesized and studied.

The title complex, systematic name catena-poly[[[acetato­chlorido­zinc(II)]-μ-(5R,6R,7S)-5-(furan-2-yl)-7-phenyl-4,5,6,7-tetra­hydro­[1,2,4]triazolo[1,5-a]py­rimi­din-6-amine] monohydrate], {[Zn(C₂H₃O₂)Cl(C₁₅H₁₅N₅O)]·H₂O}_n, is the first coordination complex in which the neutral tetra­hydro­triazolo­pyrimidine derivative acts as bridging ligand between two zinc mol­ecules. As a result, polymeric chains of the coordination complex are found. The coordination of the zinc metal atom occurs with the lone pairs of the triazolo nitro­gen atom and amino group. The positive charge of the zinc atom is compensated by the chlorine anion and deprotonated acetic acid. The coordination complex exists as a monohydrate in the crystalline phase. The water mol­ecules bind neighbouring polymeric chains by the formation of O—H⋯O, O—H⋯Cl and N—H⋯O hydrogen bonds.

Green Formation of Novel Pyridinyltriazole-Salicylidene Schiff Bases

AIM AND OBJECTIVE

In this work, water was used as solvent for the eco-friendly synthesis of imines under microwave irradiation. In the first step of the study, 5-pyridinyl-3-amino-1,2,4-triazole hydrochlorides were synthesized in the reaction of amino guanidine hydrochloride with different pyridine carboxylic acids under acid catalysis. A green method for 5-pyridinyl-3-amino-1,2,4-triazoles was developed with the assistance of microwave synthesis. In the second step, the eco-friendly synthesis of imines was achieved by reacting 5- pyridinyl-2H-1,2,4-triazol-3-amine hydrochlorides with salicylic aldehyde derivatives to produce 2-(5- pyridinyl-2H-1,2,4-triazol-3-ylimino)methyl)phenol imines.

MATERIALS AND METHODS

Microwave experiments were done using a monomode Anton Paar Monowave 300 microwave reactor (2.45 GHz). Reaction temperatures were monitored by an IR sensor. Microwave experiments were carried out in sealed microwave process vials G10 with maximum reaction volume of 10 mL.

RESULTS

When alternative methods were used, it was impossible to obtain good yields from ethanol. Nevertheless, the use of water was successful for this reaction. After 1-h microwave irritation, a yellow solid was obtained in 82% yield.

CONCLUSION

In this work an eco-friendly protocol for the synthesis of Schiff bases from 5-(pyridin-2-, 3- or 4- yl)-3-amino-1,2,4-triazoles and substituted salicylic aldehydes in water under microwave irradiation was developed. Under the found conditions the high yields for the products were achieved at short reaction time and with an easy isolation procedure.

Aminoazole-Based Diversity-Oriented Synthesis of Heterocycles

The comprehensive review contains the analysis of literature data concerning reactions of heterocyclization of aminoazoles and demonstrates the application of these types of transformations in diversity-oriented synthesis. The review is oriented to wide range of chemists working in the field of organic synthesis and both experimental and theoretical studies of nitrogen-containing heterocycles.