Development of New Thiazole Complexes as Powerful Catalysts for Synthesis of Pyrazole-4-Carbonitrile Derivatives under Ultrasonic Irradiation Condition Supported by DFT Studies

In this study, we are interested in preparing Fe(III), Pd(II), and Cu(II) complexes from new thiazole derivatives. All syntheses were elaborately elucidated to estimate their molecular and structural formulae, which agreed with those of mononuclear complexes. The square-planer geometry of Pd(II) complex (MATYPd) was the starting point for its use as a heterocatalyst in preparing pyrazole-4-carbonitrile derivatives 4a-o using ultrasonic irradiation through a facile one-pot reaction. The simple operation, short-time reaction (20 min), and high efficiency (97%) were the special advantages of this protocol. Furthermore, this green synthesis strategy was advanced by examination of the reusability of the catalyst in four consecutive cycles without significant loss of catalytic activity. The new synthesis strategy presented remarkable advantages in terms of safety, simplicity, stability, mild conditions, short reaction time, excellent yields, and use of a H₂O solvent. This catalytic protocol was confirmed by the density functional theory (DFT) study, which reflected the specific characteristics of such a complex. Logical mechanisms have been suggested for the successfully exerted essential physical parameters that confirmed the superiority of the Pd(II) complex in the catalytic role. Optical band gap, electrophilicity, and electronegativity features, which are essential parameters for the catalytic behavior of the Pd(II) complex, are based mainly on the unsaturated valence shell of Pd(II).

SLS-catalyzed Multi-component One-pot Reactions for the Convenient Synthesis of Spiro[indoline-3,4’-pyrano [2,3-c]pyrazole] Derivatives

Background,Objective: :

spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] derivatives are an important heterocyclic compounds. These compounds shows wide range of biological properties and exhibits varied pharmaceutical applications. Pyranopyrazoles, which are basically fused heterocyclic compounds and act as vasodilators, hypertensive, hypoglycaemic, and anticancer agents.

Methods:

An efficient and micelle-promoted surfactant catalyzed synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] derivatives have been achieved via one-pot four-component reaction of hydrazine hydrate (phenyl hydrazine), ethyl acetoacetate, malononitrile (ethyl cyanoacetate) and isatin under thermal conditions (at 60°C) in water as a solvent.

Results:

Sodium lauryl sulphate (SLS) used has been found to be an efficient and green catalyst. The compounds reported during this work were obtained in excellent yield, in a short duration of time and ease of work up. They were purified by recrystalization from ethanol, and also the synthesized compounds were characterized by various spectroscopic techniques.

Conclusion:

The method offers several advantages such as safe, cost-effective and catalyst easily recovered and reused for a minimum of five cycles, that confirms its good stability. Short reaction times, high yield and usage of eco-friendly catalyst and solvent are the key features of this methodology.

Greener Synthesis of Nitrogen-Containing Heterocycles in Water, PEG, and Bio-Based Solvents

The solvents used in chemistry are a fundamental element of the environmental performance of processes in corporate and academic laboratories. Their influence on costs, health safety, and nature cannot be neglected. Quantitatively, solvents are the most abundant constituents of chemical transformations; therefore, acting on solvents and replacing standard solvents with safer products can have a great ecological impact. However, not all green solvents are suitable for the wide scope of organic chemistry reactions. A second point to consider is that 50% of pharmaceutical drugs are nitrogen heterocycles compounds. It therefore appeared important to provide an overview of the more ecological methodologies for synthesizing this class of compounds. In this review, all publications since 2000 that describe green reactions leading to the formation of nitrogen heterocycles using safe solvents were considered. We chose water, PEG, and bio-based solvents for their negligible toxicity. The synthesis of five-, six-, and seven-membered aromatic nitrogen heterocycles using green reactions reported in the literature to date is described.

Sulphated alumina tungstic acid (SATA): a highly efficient and novel heterogeneous mesostructured catalyst for the synthesis of pyrazole carbonitrile derivatives and evaluation of green metrics

A novel mesostructured catalyst sulphated alumina tungstic acid (SATA) has been prepared by an easy route. Various techniques such as IR, XRD, SEM, EDX, TEM, TGA and BET were used to characterize the synthesized catalyst. The catalytic activity of the meso material has been explored by synthesizing a series of new pyrazole carbonitrile derivatives from aromatic aldehydes, ethylcyanoacetate, phenylhydrazine/hydrazine hydrate in ethanol under reflux conditions. Furthermore, the “greenness” of this protocol when estimated by green metrics, displayed satisfactory results. The protocol is free from column chromatography, and toxic solvents and is more efficient as compared to reported ones.

A novel mesostructured catalyst sulphated alumina tungstic acid (SATA) has been prepared by an easy route.

Visible light triggered, catalyst free approach for the synthesis of thiazoles and imidazo[2,1-b]thiazoles in EtOH : H2O green medium

A catalyst free visible light assisted synthesis of thiazoles and imidazo[2,1-b]thiazoles in EtOH : H₂O green medium.

Synthesis of pyrazole derivatives in the presence of a dioxomolybdenum complex supported on silica-coated magnetite nanoparticles as an efficient and easily recyclable catalyst

A dioxomolybdenum complex supported on functionalized Fe₃O₄ magnetite nanoparticles as a heterogeneous catalyst was synthesized, characterized and used in the synthesis pyrazole derivatives.

Microwave-assisted synthesis of novel 2,3-disubstituted imidazo[1,2-a]pyridines via one-pot three component reactions

An expeditious one-pot, metal-free, three-component reaction of arylglyoxals, cyclic 1,3-dicarbonyls and 2-aminopyridines in the presence of molecular iodine under microwave irradiation is reported.

Catalytic applications of {[HMIM]C(NO2)3}: as a nano ionic liquid for the synthesis of pyrazole derivatives under green conditions and a mechanistic investigation with a new approach

1-Methylimidazolium trinitromethanide {[HMIM]C(NO₂)₃} as a nano structure ionic liquid was applied for the synthesis of pyrazole derivatives with high yields under mild and green conditions.

A green and efficient protocol for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives via a one-pot, four component reaction by grinding method

An efficient grinding protocol for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives from acetylene ester, hydrazine hydrate, aryl aldehydes and malononitrile under solvent free conditions has been achieved with excellent yields. The structures of the synthesized compounds were deduced by spectroscopic techniques and the compounds were further evaluated for their in vitro antioxidant and antimicrobial activities.