Piperazine, a six membered nitrogen containing heterocycle, is of great significance to the rational design of drugs. This moiety can be found in a plethora of well-known drugs with various ...therapeutic uses, such as antipsychotic, antihistamine, antianginal, antidepressant, anticancer, antiviral, cardio protectors, anti-inflammatory, and imaging agents. Slight modification to the substitution pattern on the piperazine nucleus facilitates a recognizable difference in the medicinal potential of the resultant molecules.
Scifinder was the main source used to search for patents containing piperazine compounds with therapeutic uses. The article describes a variety of molecular designs bearing piperazine entity furnishing CNS agents, anticancer, cardio-protective agents, antiviral, anti-tuberculosis, anti-inflammatory, antidiabetic, and antihistamine profiles, as well as agents relieving pain and useful in imaging applications.
The great interest gathered to explore piperazine based molecules in relatively few years reflects the broad potential of the entity. Earlier, this scaffold was considered to express CNS activity only. However, a significant increase in research covering studies of several different activities of piperazine ring suggest a successful emergence of the pharmacophore. Certain patents outlined in the present article recommend that piperazines can be a flexible building block to discover drug-like elements and modification of substituents present on the piperazine ring may have a significant impact on the pharmacokinetic and pharmacodynamics factors of the resulting molecules. This article aims to provide insights to piperazine based molecular fragments that would assist drug discoverers to rationally design molecules for various diseases. We anticipate, and highly recommend, further therapeutic investigations on this motif.
Magnetite-sulfonic acid (Nanocat-Fe-OSO sub(3)H), prepared by the wet-impregnation method, serves as a magnetically retrievable sustainable catalyst for the Ritter and multicomponent reactions. The ...as synthesized catalyst can be used in several reaction cycles without any loss of activity.
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Gold nanoparticles (∼13nm, 4% Au) dispersed on reduced graphene oxide (Au/rGO) were prepared via reduction of gold (III) complex and used for the oxidation reactions under benign ...conditions.
•Gold nanoparticles (10–13nm, 4% Au) dispersed over the reduced graphene oxide support (Au/rGO).•High efficiency for the oxidation of ethyl benzene and the oxidative esterification of aldehydes.•Good to excellent yields using oxygen as an environmentally-friendly oxidant.•Recyclable up to five cycles without decreasing its catalytic activity.
Gold nanoparticles (∼13nm, 4wt% Au) dispersed on reduced graphene oxide (Au/rGO) surface were prepared via the reduction of gold (III) chloride using sodium citrate on reduced graphene oxide support. The chemical, morphological, and size analyses of Au/rGO by XRD, XPS, TEM, HR-TEM/EDS, AAS, and Raman spectroscopy revealed that the hybrid material comprised of a well-defined rGO support decorated with gold nanoparticles. The ensuing catalyst was evaluated for the oxidation of ethyl benzenes (yields up to 95%) and oxidative esterification of aldehydes (73–97%) using oxygen as an environmentally friendly oxidant in good to excellent yields; reusable and recyclable catalyst displayed high activity without the use of toxic organic solvents.
A nanocatalyst comprising ultra-small Pd/PdO nanoparticles (<5 nm) supported on maghemite was prepared by a co-precipitation protocol using inexpensive raw materials and was deployed successfully in ...various significant synthetic transformations, namely the Heck–Mizoroki olefination (up to 95%), the Suzuki reaction (60–95%), and the allylic oxidation of alkenes under milder conditions. The chemical nature, morphology, size, and loading of palladium nanoparticles over the magnetic support were studied by TEM/EDX, HAADF-STEM chemical mapping, XPS, AAS, and in-field
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Fe Mössbauer spectroscopy. The cost-effective catalyst could be easily separated from the reaction mixture by using an external magnet and reused four times without any loss of activity; chemical stability and recyclability aspects of the catalyst were investigated.
Cancer accounts for a number of deaths each year. Consequently, prevention of this deadly disease is more challenging and hence the invention of new anticancer agents is of utmost importance. The ...current review elaborates the importance of indole designs as patented in the form of anticancer druglike molecules targeting different cites of biological arena. Specific attention was given to kinases such as platelet-derived growth factor receptor, vascular endothelial growth factor receptor and fibroblast growth factor receptor, Bruton's tyrosine kinase, anaplastic lymphoma kinase, Janus kinase, cyclin-dependent kinase aurora kinases A, B and C, checkpoint kinases, protein kinase R, Pim kinases, phosphoinositide 3- kinase, altered proteins kinases, polo-like kinase and many more. Moreover, the article summarizes the mode of action through the particular functions of kinases and the inhibitory potential of indole derivatives toward specific kinase. Certain patents gathered in the existing review article suggest that indole core can be a versatile foundation to discover drug-like kinase inhibitor molecules and modification of substituents existing on the indole moiety may have important impact on the pharmacokinetic and pharmacodynamics aspects of the resultant scaffolds. The information presented here would gather a great deal of interest to identify the new molecular designs bearing indole nucleus presenting novel anticancer drugs with a wide variety of biological targets involved in cancer pathology focusing on the inhibition of tyrosine kinases, serine/threonine-specific protein kinases, cyclin-dependent kinases, lipid kinases and altered protein kinases.
Core–shell nanocatalysts are a distinctive class of nanomaterials with varied potential applications in view of their unique structure, composition-dependent physicochemical properties, and promising ...synergism among the individual components. A one-pot microwave (MW)-assisted approach is described to prepare the reduced graphene oxide (rGO)-supported Pd–Pt core–shell nanoparticles, (Pd@Pt/rGO); spherical core–shell nanomaterials (∼95 nm) with Pd core (∼80 nm) and 15 nm Pt shell were nicely distributed on the rGO matrix in view of the choice of reductant and reaction conditions. The well-characterized composite nanomaterials, endowed with synergism among its components and rGO support, served as catalysts in aromatic dehalogenation reactions and for the reduction of olefins with high yield (>98%), excellent selectivity (>98%) and recyclability (up to 5 times); both Pt/rGO and Pd/rGO and even their physical mixtures showed considerably lower conversions (20 and 57%) in dehalogenation of 3-bromoaniline. Similarly, in the reduction of styrene to ethylbenzene, Pd@Pt core–shell nanoparticles (without rGO support) possess considerably lower conversion (60%) compared to Pd@Pt/rGO. The mechanism of dehalogenation reactions with Pd@Pt/rGO catalyst is discussed with the explicit premise that rGO matrix facilitates the adsorption of the reducing agent, thus enhancing its local concentration and expediting the hydrazine decomposition rate. The versatility of the catalyst has been validated via diverse substrate scope for both reduction and dehalogenation reactions.
Reduction by magnetic nano‐Fe3O4–Ni: A facile, simple and environmentally friendly hydrogen‐transfer reaction that takes place over recyclable ferrite–nickel magnetic nanoparticles (Fe3O4Ni) by ...using glycerol as hydrogen source allows aromatic amines and alcohols to be synthesized from the precursor nitroarenes and carbonyl compounds (see figure).
An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses a magnetically separable and reusable ...maghemite-supported gold nanocatalyst (nanocat-Fe-Au) under mild conditions. The complex chemical, morphological, structural and size analyses, including e.g.XPS, HRTEM, in-field Mossbauer spectroscopy and HRTEM, revealed that the hybrid material is composed of a well-defined stoichiometric maghemite support (20-30 nm) decorated with ultrasmall (5-6 nm) gold nanoparticles. The hybrid catalytic system containing 4 wt% of nanogold has been generated using simple impregnation methods in aqueous medium from readily available starting materials and was recycled five times without any significant loss in catalytic activity; high yields, 40-95% and 83-94% for oxidative esterification and reduction reactions, respectively, were obtained.
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing ...magnetic catalyst is well characterized by XRD, FE-SEM, TEM, N
adsorption-desorption isotherm, and Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and can be recycled up to 10 times without any loss in catalytic activity.
•Microwave (MW)-assisted methodology can improve conventional heating techniques.•MW-assisted catalytic reactions performed in aqueous medium are summarized.•Newer developments on continuous flow ...capillary MW microreactors are described.•Heterocycles, cross-coupling and CH activation reactions are highlighted.
The development of sustainable methods directed towards the synthesis of molecules is due to the heightened awareness and recognition of alternative eco-friendly and economical protocols that have minimum impact on environment. Among others, microwave (MW)-assisted methodology has matured and can be used safely to substitute for conventional laboratory heating techniques; a number of chemical transformations have been achieved thereby improving many existing protocols with superior results when compared to reactions performed under conventional heating conditions. The focus of this review is to summarize recent MW-assisted catalytic reactions performed in aqueous media for the development of environmentally benign protocols. We review the catalytic MW-assisted methods employed for the synthesis of a variety of heterocycles, cross-coupling reactions, CH activation reactions, synthesis of peptides, ureas, and carboxyl-containing coordination polymers and a host of miscellaneous reactions. In addition, some recent newer developments such as continuous flow capillary MW microreactors and other related flow applications are included. This sustainable approach represents the fusion of friendly reaction medium (water) and microwave activation in conjunction with a variety of catalysts.
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