The increasing demand of simple, clean, and sustainable protocols for the preparation of complex organic molecules have continuously encouraged researchers to discover and design modern methodologies. Metal-catalyzed multicomponent reactions (MCRs)...

A novel and simple approach for the efficient and rapid synthesis of pyrano[2,3-c]-pyrazoleshas been accomplished via the four-component condensation reaction of malononitrile, hydrazine hydrate, ethyl acetoacetate, and substituted aldehydes using MIL-53(Fe) metal-organic framework (MOF) as a catalyst in ethanol at room temperature. Recycling studies have shown that the MIL-53(Fe) can be readily recovered and reused six times without significant loss of its activity. The present protocol offers the advantages including short reaction times, simple workup, high yields, elimination of toxic solvents, no chromatographic purification and recoverability of the catalyst. Also, the catalyst was fully characterized by SEM, EDX, FT-IR, XRD, TGA and TEM analysis.

An efficient and green approach is reported for the rapid synthesis of spirocyclic 2-oxindole using triethylenediamine or imidazole Brønsted acidic ionic liquids supported in Zr metal-organic framework (TEDA/IMIZ-BAIL@UiO-66) as a novel, superior and retrievable heterogeneous catalyst under ultrasonic irradiation. Heterocyclic compounds including pyrido[2,3d:6,5-d′]dipyrimidines and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidines were obtained by the one-pot condensation reaction of 6-amino-1,3-dimethyluracil, isatins and cyclic 1,3-diketone (barbituric acid or 1,3-indanedione). The reusability of the catalyst, low catalyst loading, short reaction times, excellent yields, simple work-up, and use of sonochemical procedure as a mild process and an alternative energy source are some of the advantages of this method. Furthermore, the novel heterogeneous nanocomposite was fully characterized using various techniques.

The effective and simple one-pot, three-component protocol for the synthesis of dihydropyrido[2,3- d ]pyrimidine derivatives is presented using a triethylenediamine or imidazole Brönsted acidic, ionic-liquid-supported Zr metal–organic framework (TEDA/IMIZ-BAIL@UiO-66) as a green, novel, and retrievable heterogeneous catalyst under mild conditions. The multicomponent reactions of 6-amino-1,3-dimethyl uracil, various aromatic aldehydes, and acetyl acetone were conducted under solvent-free conditions so that dihydropyrido[2,3- d ]pyrimidine derivatives can be obtained. It is possible to separate and purify the respective products easily using crystallization. We can recycle the catalysts six times without losing any major activity. Also, the characterization of the catalyst was done by energy-dispersive X-ray, field emission scanning electron microscopy, Fourier transform infrared, Brunauer–Emmett–Teller, X-ray diffraction, and thermogravimetric analysis analyses.

In this study, HMTA-BAIL@MIL-101(Cr) was prepared as a novel catalyst for the synthesis of dipyrimidine derivtives by the reaction of barbituric acids, 6-aminouracil/6-amino-1,3-dimethyl uracil, and arylaldehydes under solvent-free conditions.

′ -indoline]-trione derivatives from a three-component condensation reaction of 1,3-indandione, aromatic amines and isatins in the presence of a zinc terephthalate metalorganic framework Zn (BDC) MOF as the catalyst under solvent-free conditions. High yields, short reaction times, simple workup and environmentally benign procedure are advantages of this protocol. The Zn (BDC) MOF catalyst can be recovered and reused several times without loss of activity. The catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infra red, X-ray powder diffraction and thermal gravimetric analysis. ARTICLE HISTORY

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