A Novel and Efficient Five-Component Synthesis of Pyrazole Based Pyrido[2,3-d]pyrimidine-diones in Water: A Triply Green Synthesis.

A novel one pot synthesis of pyrazolo[4',3':5,6]pyrido[2,3-d]pyrimidine-diones, via a five-component reaction, involving, hydrazine hydrate, ethyl acetoacetate, and 1,3-dimethyl barbituric acid, an appropriate aryl aldehydes and ammonium acetate catalyzed via both of heterogeneous and homogeneous catalysis in water, is reported.

Current advances in the synthesis and biological potencies of tri- and tetra-substituted 1H-imidazoles.

In this report, we review the current chemistry progress and in particular the synthesis approaches of tri- and tetra-substituted imidazoles.

Hal-Py-SO3H as a novel and recyclable catalyst for highly efficient synthesis of xanthene and spiropyran derivatives.

The aim of this research is to synthesize a new sulfonic acid catalyst based on halloysite nanotubes (Hal-Py-SO3H) and characterize it as a solid acid nanocatalyst by various analytical techniques such as Fourier-Transformed Infrared spectroscopy (FTIR), Thermal gravimetric Analysis (TGA), X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Vibrating Energy-Dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and X-ray atomic mapping. Furthermore, this new catalyst was evaluated in synthesizing spiropyran derivatives via multicomponent reactions (MCRs) and Xanthen derivatives under environmentally sustainable conditions. The main advantages of this approach include green conditions, excellent yields, quick reaction rates, and ease of preparation. Additionally it was observed that the catalyst exhibited robust stability even after multiple recycling processes, indicating its potential for practical applications in sustainable chemical transformations.

Heteropolyacid coupled with cyanoguanidine decorated magnetic chitosan as an efficient catalyst for the synthesis of pyranochromene derivatives.

In this study, a novel nanocatalyst was successfully prepared by heteropolyacid immobilization of magnetic chitosan-cyanoguanidine composite and fully characterized by different analysis methods, including FTIR, XRD, TGA, SEM, and EDS. The catalytic activity of fabricated composite was examined in a one-pot three-component reaction, involving the diverse active methylene compounds, various aryl aldehydes, and malononitrile in water. The results revealed the efficient catalytic performance of composite, while all reactions proceeded smoothly and led to the formation of the corresponding pyranochromene derivatives in high to excellent yields.

Lanthanoid-containing polyoxometalate nanocatalysts in the synthesis of bioactive isatin-based compounds.

Lanthanoid-containing polyoxometalates (Ln-POMs) have been developed as effective and robust catalysts due to their Lewis acid-base active sites including the oxygen-enriched surfaces of POM and the unique 4f. electron configuration of Ln. As an extension of our interest in Ln-POMs, a series of as-synthesized nanocatalysts K15[Ln(BW11O39)2] (Ln-B2W22, Ln = La, Ce, Nd, Sm, Gd, and Er) synthesized and fully characterized using different techniques. The Ln3+ ion with a big ionic radius was chosen as the Lewis acid center which is sandwiched by two mono-lacunary Keggin [BW11O39]9- units to form Ln-containing sandwiched type cluster. Consequently, the catalytic activity of nanocatalysts with different Ln was examined in the synthesis of bioactive isatin derivatives and compared under the same optimized reaction conditions in terms of yields of obtained products, indicating the superiority of the nano-Gd-B2W22 in the aforementioned simple one-pot reaction. The effects of different dosages of nanocatalyst, type of solvent, reaction time, and reaction temperature in this catalytic system were investigated and the best results were obtained in the presence of 10 mol% of nano-Gd-B2W22 in water for 12 min at the reflux condition.

Ag nanoparticles immobilized on new magnetic alginate halloysite as a recoverable catalyst for reduction of nitroaromatics in aqueous media.

Amines can be applied in the synthesis of various important compounds such as dyes, drugs, polymers, pharmaceutical products, and biologically active materials. The significant subject in the preparation of amines is the selection of the most effective heterogeneous catalyst to get the best catalytic efficiency, stability, recoverability, and reusability. For this target, we prepared new alginate magnetically recoverable nanocatalyst by stabilization of Ag nanoparticles on the surface of the halloysite (HS) [HS-Alginate-Ag/Fe3O4]. Several detection methods confirmed the production of HS-Alginate-Ag/Fe3O4 nanocatalyst and the results obtained were well explained in the context. HS-Alginate-Ag/Fe3O4 presented good catalytic performance for the hydrogenation of nitro compounds using NaBH4 as the reducing agent and hydrogen donor. The good activity and durability of this catalyst can be attributed to the good dispersion and nano-sized particle of silver nanoparticles.

Silver incorporated into g-C3N4/Alginate as an efficient and heterogeneous catalyst for promoting click and A3 and KA2 coupling reaction.

Fe3O4/g-C3N4/Alginate-Ag nanocomposite as a novel and effective nanocatalyst was successfully prepared. This nanocomposite was fully characterized using several techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). In addition, the catalytic activity of this novel and characterized nanocatalyst was investigated in the regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles via click reaction and A3 and KA2 coupling reaction in aqueous media. The prepared nanocatalyst was simply recovered by using an external magnet and reused for several times with a slight loss of catalytic activity.

Investigation of halloysite nanotubes and Schiff base combination with deposited copper iodide nanoparticles as a novel heterogeneous catalytic system.

The design, preparation and characterization of a novel composite based on functionalization of halloysite nanoclay with Schiff base followed by immobilization of copper iodide as nanoparticles is revealed. This novel nano composite was fully characterized by utilization of FTIR, SEM/EDX, TGA, XRD and BET techniques. This Cu(I) NPs immobilized onto halloysite was successfully examined as a heterogeneous, thus easily recoverable and reusable catalyst in one of classist organic name reaction so-called "Click Reaction". That comprised a three component reaction of phenylacetylene, α-haloketone or alkyl halide and sodium azide in aqueous media to furnish 1,2,3-triazoles in short reaction time and high yields. Remarkably, the examination of the reusability of the catalyst confirmed that the catalyst could be reused at least six reaction runs without appreciable loss of its catalytic activity.

Pd NPs supported on halloysite functionalized with Schiff base as an efficient catalyst for Sonogashira reaction.

A hybrid system was designed and synthesized through reacting modified halloysite (Hal-Cl) with Schiff base (DAB-PC) and applied as catalytic support for anchoring Pd NPs to afford Pd@Hal-DAB-PC catalyst. The resultant material was well identified by various analyses including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction patterns (XRD), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and inductively coupled plasma-optical emission spectrometry (ICP-OES) and revealed outstanding catalytic activity in the Sonogashira reaction in aqueous media. Also, This nanocatalyst was simply collected and recycled up to six runs with a slight drop in efficiency, indicating the durability of Pd@Hal-DAB-PC.

Recent applications of the Wittig reaction in alkaloid synthesis.

The Wittig reaction is the chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide (the Wittig reagent) to afford an alkene and triphenylphosphine oxide. Noteworthy, this reaction results in the synthesis of alkenes in a selective and predictable fashion. Thus, it became as one of the keystone of synthetic organic chemistry, especially in the total synthesis of natural products, where the selectivity of a reaction is paramount of importance. A literature survey disclosed the existence of vast numbers of related reports and comprehensive reviews on the applications of this important name reaction in the total synthesis of natural products. However, the aim of this chapter is to underscore, the applications of the Wittig reaction in the total synthesis of one the most important and prevalent classes of natural products, the alkaloids, especially those showing important and diverse biological activities.

Fe(ClO4)3 x 6H2O: a mild and efficient catalyst for one-pot three component synthesis of beta-acetamido carbonyl compounds under solvent-free conditions.

A one-pot multi-component reaction for the synthesis of beta-acetamido carbonyl compounds is reported. The reaction uses a variety of aldehydes, acetophenone derivatives or methyl acetoacetate, acetonitrile, and acetyl chloride in the presence of ferric perchlorate, a mild, efficient and inexpensive catalyst effective under solvent free conditions.

A biocompatible chitosan-ionic liquid hybrid catalyst for regioselective synthesis of 1,2,3-triazols.

A new type of quadruple hybrid system was prepared containing chitosan (CS), folic acid (FA), Poly(styrene-co-maleic anhydride) [SMA] and ionic liquid (IL). This nanocatalyst was synthesized by the functionalization of SMA with folic acid and then polymerization with chitosan in the presence of DCC and NHS. CuI was immobilized onto this support to provide Cu@SMA-FA-CS-IL. The catalyst was fully characterized by using different characterization techniques such as FTIR, 1H NMR, ICP, SEM, EDX, TGA, and XRD. This Cu (I) heterogeneous species was successfully applied in the reaction of sodium azide, terminal alkynes, and alkyl halides or α-haloketones in water to afford 1,4-disubstituted-1,2,3-triazoles within relatively short reaction times. Moreover, the catalyst is recyclable for five reaction cycles with minor CuI leaching and slight drop of the catalytic activity.

Acid-functionalized Mesoporous Silicate (KIT-5-Pr-SO3H) Synthesized as an Efficient and Nanocatalyst for Green Multicomponent.

AIM AND OBJECTIVE: KIT-5 nanoporous silica was functionalized with sulfonic acid and SO3H group has been immobilized on nanoporous KIT-5 silica support via in situ method to produce novel nanocatalyst as "KIT-5-Pr-SO3H". The catalyst was fully characterized by FT-IR, SEM, EDXs, TEM, BET and TGA techniques. The surface morphology images approved that the nanocatalyst particle sizes are around 7-15 nm. The prepared catalyst was efficiently used in the synthesis of benzimidazolo quinazolinones, imidazo[1,2- a]chromeno[4,3-d]pyrimidinone and imidazo[1,2-a]pyrimidine via a multicomponent reaction under green conditions. The easy synthesis condition, environmental compatibility, high specific surface area, reusability for 5 run without loses in any activity, high selectivity, availability of raw material, are the remarkable properties for this new catalyst. MATERIALS AND METHODS: All reagents were purchased from Aldrich and Merck with high-grade quality and used as received. The structural characteristics of the KIT-5 which was obtained, using three-dimensional large cage type face-centered cubic Fm3m mesoporous silica materials (KIT-5) nanocages were obtained according to the procedure described by Kleitz et al. Results: The purpose of this study is developing a new acid-functionalized mesoporous catalyst. Initially, (KIT-5) nanocages were obtained according to the procedure described by Kleitz et al. Then, KIT-5-Pr-SH was prepared by Mercaptopropyltriethoxysilane as illustrated in Scheme 1. In the next step, the solid product was oxidized with H2O2. The full characterization for proving the structure of the nano-size particles was achieved using FT-IR, TGA, TEM, SEM, and EDX analysis. CONCLUSION: Acid-functionalized mesoporous silica has been proved to act as an effective catalyst in various organic reactions. In this project, for the first time, KIT-5 was functionalized by propyl-sulfonic acid as a heterogeneous solid acid catalyst. Sulfonic acid functionalized KIT-5 (KIT-5-Pr-SO3H) performs as an organicinorganic hybrid catalyst, whereas Brønsted acid sites have been selectively generated. In this regard, the catalytic activities of this novel heterogeneous catalyst were successfully examined by the one-pot multicomponent reaction.