Catalyzed Condensation Reaction Research Articles

Nitrogen Enriched Tröger's Base Polymers of Intrinsic Microporosity for Heterogeneous Catalysis.

Heterogeneous catalysis is significantly enhanced by the use of highly porous polymers with specific functionalities, such as basic groups, which accelerate reaction rates. Polymers of intrinsic microporosity (PIMs) provide a unique platform for catalytic reactions owing to their high surface areas and customizable pore structures. We herein report a series of Tröger's base polymers (TB-PIMs) with enhanced basicity, achieved through the incorporation of nitrogen-containing groups into their repeat units, such as triazine and triphenylamine. These polymers offer a perfect balance between the pore "swellability", which allows the use of substrates of various dimensions, and the basicity of their repeat units, which facilitates the use of reactants with diverse acidity. The catalytic activity is evaluated through the Knoevenagel condensation of benzaldehydes and various methylene species, conducted in the presence of ethanol as a green solvent and using a 1:1 ratio of the two reagents. The results highlight a significant improvement, with reactions reaching completion using just a 1% molar ratio of catalysts and achieving a 3-fold enhancement over previous results with 4-tert-butyl-benzaldehyde. Computational modeling confirms that the enhanced basicity of the repeat units is attributable to the polymer design. Additionally, preliminary studies are undertaken to assess the kinetics of the catalyzed condensation reaction.

Candida antarctica lipase B catalyzed condensation reactions: Water mediated chemo-enzymatic synthesis of different heterocycles

A water-mediated, chemoenzymatic reaction has been developed for synthesizing various heterocycles. This reported method is compatible with various condensation reactions and multi-component reactions, such as the Biginelli reaction. It offers direct access to benzothiazole, benzimidazole, benzoxazole, quinazolinone, and pyrimidines using straightforward reaction conditions, adhering to green chemistry principles.

One‐pot synthesis of a giant twisted double‐layer chiral macrocycle via [4 + 8] imine condensation and its X‐ray structure

Trifluoroacetic acid (TFA) catalyzed condensation reaction between tetraaminooxacalix[4]arene and N-alkylcarbazole-3,6-dicarbaldehyde in CH2Cl2 afforded a single product in 87%–89% yield. Well-defined yet undissolvable 1H NMR spectra suggested formation of robust and discrete structures in solution. X-ray single crystal analysis further revealed a giant twisted double-layer chiral macrocycle in the solid state, which was formed from [4 + 8] condensation of the two reactants via 16 imine bonds. DFT calculations discovered that only the [4 + 8] twisted product is thermodynamically favorable, which accounts for its highly selective and efficient formation out of a library of many other combinations.

Antimicrobial activity of Dibenzalacetone (C17H14O)

Dibenzalacetone was synthesized via the base catalysed condensation reaction between acetone and benzaldehyde. This study was done to evaluate the antimicrobial activity of the synthesized compound dibenzalacetone (C17H14O) against four human pathogenic microorganisms: Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginiosa and the fungus Candida albicans. The highest area of zone of inhibition of 68.23 mm2 was induced against Candida albicans and the lowest AZOI of 37.55 mm2 was induced against E.coli. Staphylococcus aureus was totally resistant to the drug, in that zero zone of inhibition was induced against dibenzalacetone. The order of antimicrobial potency followed the sequence: Candida albicans > Klebsiella pneumoniae > Pseudomonas aeruginosa > Staphylococcus aureus. However, its antimicrobial potency was lowered than that of standard synthetic drug, Ampicillin and Ketoconazole.

Facile synthesis and photodetection characteristics of new pyrrolo[2,3-b]pyrrole-based metal-free organic dyes containing phenols as the potential candidates towards energy conversion

A new characteristic with inexpensive preparation tools and best application performance is needed. These new properties have been achieved by using novel heterocyclic dyes by attaching different electron-rich aromatics to the pyrrolo[2,3-b]pyrrole system. A new derivatives of diethyl 3,4-diamino-1,6-diphenyl-1,6-dihydropyrrolo [2,3-b]pyrrole-2,5-dicarboxylate (PPy) (compound 1) was easily and efficiently synthesized using catalyzed condensation reaction. The final push-pull conjugated dyes were yielded by azo coupling with resorcinol, and 2-naphthol, denoted as compounds 2 and 3, respectively. Very good adhesive and homogenous thin films of these compounds are successfully prepared by thermal evaporation technique. On the basis of its corrected analytical and spectral data, the structure of these compounds was determined. The relation between dye structures, photophysical, and molecular structures had been discussed. The unique simulation characteristics of the prepared compounds 1–3 were achieved by density functional theory, DFT/B3LYP, using 6–311 ++ G (d,p) basis set. Optical spectra have revealed a large direct band gap at 3.99, 3.15, and 2.85 eV for compounds 1, 2, and 3 respectively, corresponding to π−π* transitions. Finally, an experimental approach was used to determine the exciton binding energy to depict Frenkel exciton binding energy. The properties of these compounds proved that it is more suitable as a potential application for energy conversion.

Heteropoly Acids an Efficient Catalyst for Ultrasound Promoted Synthesis of Substituted Indazole

A clean and simple methodology was developed for the synthesis of substituted indazoles using heteropoly acids containing tungsten, molybdenum metal catalyzed condensation reaction between substituted 2-hydroxy benzaldehydes/acetophenones and hydrazine hydrate/phenyl hydrazine. The reaction conditions are optimized for two different heteropoly acids such as H3PMo12O40 and H3PW12O40 using conventional and ultrasound sonication method. Yield of the products improved to 92 to 95% using H3PW12O40 heteropoly acid as catalyst which is reusable, cost effective and easy to handle.

Synthesis, DFT Calculations, DNA Binding and Molecular Docking Studies on Biologically Active N-((3-(4-Methoxyphenyl)-1-phenyl-1H-pyrazol-4-yl)methylene)naphthyl Derivatives

The biologically active pyrazole clubbed imino naphthyl derivatives have been designed and synthesized from 1-phenyl-3-methoxy phenyl-1H-pyrazol-4-carboxaldehyde and substituted naphthyl amines via acid catalyzed condensation reaction. All the synthesized compounds were well characterized by different spectroscopic and mass spectral techniques. The in vitro antibacterial, antifungal and antituberculosis studies were carried out. The molecular docking study was also done with the software Arguslab 4.0.1. The studied compounds showed moderate to good biological activities both experimentally and theoretically. Geometry optimization, DNA binding interaction and FMO analysis were also investigated with the help of Gaussian 16 package at B3LYP/6-31G(d,p) level.

Water extract of pomegranate ash as waste-originated biorenewable catalyst for the novel synthesis of chiral tert‑butanesulfinyl aldimines in water

• Biorenewable waste-derived base as catalyst in water. • Highly sustainable synthesis of chiral tert ‑butanesulfinyl aldimines. • Non-chromatographic purification of products. • Fair reusability of the renewable catalyst and multi-gram scale viability. The renewable materials catalyzed reactions in aqueous media is urgently needed and highly fascinating task in the current state of organic synthesis. Here, we report a novel and sustainable protocol for the biorenewable, waste-originated water extract of pomegranate ash (WEPA) catalyzed condensation reaction of tert ‑butanesulfinamides and aldehydes in water to produce chiral tert ‑butanesulfinyl aldimines ( t BSAIs) in high yields. The products are separated by filtration and purified by recrystallization; avoids the extraction and column chromatographic separation steps. The reaction was performed with high yields in several consecutive recycles of the catalyst and medium, and further this method is highly effective for the multi-gram scale synthesis of t BSAIs. The application of biorenewable catalyst, added metal/catalyst free conditions, absence of volatile organic solvents and additives, vast substrate feasibility, economical profiles, easy operation, reusability of the catalyst, large scale viability, non-chromatographic purification of products and tremendous future perspective are the sparkling insights of this development. A novel and versatile protocol has been developed for the synthesis of tert‑butanesulfinyl aldimines using water extract of pomegranate ash (WEPA) as catalyst in water.

Facile synthesis, DNA binding, Urease inhibition, anti-oxidant, molecular docking and DFT studies of 3-(3-Bromo-phenyl)-1-(2-trifluoromethyl-phenyl)-propenone and 3-(3-Bromo-5 chloro-phenyl)-1-(2-trifluoromethyl-phenyl)-propenone

Two new chalcones namely 3-(3-Bromo-phenyl)-1-(2-trifluoromethyl-phenyl)-propenone (1) and 3-(3-Bromo-5-chloro-phenyl)-1-(2-trifluoromethyl-phenyl)-propenone (2) were synthesized from substituted aldehydes and fluorinated acetophenone through base catalyzed condensation reaction. The structural confirmation of synthesized compounds was furnished by different spectroscopic techniques i.e., (1H NMR, FT-IR, mass spectrometry and UV–visible analysis). The interaction of 1 and 2 with Salmon sperm DNA (SS-DNA) was studied using UV–visible spectroscopy. The Urease inhibition and antioxidant potential were also evaluated experimentally which were further supported by molecular docking studies. To investigate drug discovery endeavors of our synthesized compounds ADME properties were explored. The calculations of frontier molecular orbitals (FMOs), natural population analysis (NPA), natural bond orbitals (NBOs) and nonlinear optical (NLO) analysis of 1 and 2 were performed at B3LYP/6-311 G(d,p) level of DFT. Time dependent density functional theory (TD-DFT) was used to describe photo-physical properties of synthesized compounds. Additionally, natural population analysis (NPA) and NBO were used to explore inter and intra molecular interactions as well as hyper conjugative interactions. The experimental results revealed that the compounds 1 and 2 interact strongly with SS-DNA through intercalation mode. UV/Vis spectrum obtained from DFT calculations correlates very well with the experimentally obtained spectrum. Furthermore, DFT studies showed that hyper conjugative interactions lead to higher stabilization of 2 than 1.

Highly efficient synthesis and characterization of starch aldehyde-catechin conjugate with potent antioxidant activity

In this study, cassava starch aldehyde was functionalized with catechin through acid catalyzed condensation reaction. The structural characterization, stability and antioxidant activity of starch aldehyde-catechin conjugates were investigated. Thin layer chromatography revealed the conjugates did not contain free catechin. UV–vis spectra of the conjugates exhibited an absorption band at 280 nm, attributing to the B-ring of catechin moiety. Fourier-transform infrared and proton nuclear magnetic resonance spectroscopy demonstrated the conjugation occurred between the H–6/H–8 of catechin A-ring and the aldehyde groups of starch aldehyde. X-ray diffraction pattern indicated that the conjugates had an amorphous structure. Scanning electron microscopy showed the conjugates were fragmentary slices with rough surfaces. Notably, the conjugates were more stable than catechin in phosphate buffered saline (pH 7.4). In addition, the conjugates could not be digested in simulated saliva, gastric and small intestinal juices. The reducing power and free radical scavenging activity of starch aldehyde were remarkably elevated by conjugating with catechin. Meanwhile, the conjugates were non-cytotoxic to RAW264.7 mouse macrophage cells and possessed higher resistant starch contents than starch. Our results suggest starch aldehyde-catechin conjugates can be used as antioxidants in food industry.

One-step synthesis of hydroxyl-functionalized fully carbon main chain PIMs via a Friedel-Crafts reaction for efficient gas separation

High performance, robust polymeric membranes are playing more and more important roles in recent large scale industrial gas separation applications. One of the biggest challenges is scaling up the high performance polymeric materials. Herein, a one-step super-acid catalyzed condensation reaction was reported to synthesize two novel hydroxyl-functionalized fully carbon main chain intrinsic microporous polymers (HSBI-Is and HBIN-Is) with high efficiency. Both polymers demonstrated high molecular weight, good thermal stability with Td above 360 °C, and modest microporosity. HSBI-Is exhibited a more open structure with higher BET surface area (523 vs 57 m2 g−1), larger fractional free volume (0.212 vs 0.162), and d-spacing (5.16 vs 3.68 Å) than HBIN-Is due to its more rigid and bulky spirobisindane (SBI) site of contortion. Membranes based on HSBI-Is and HBIN-Is showed moderate to high permeabilities and selectivitites with H2/N2, H2/CH4, O2/N2 and CO2/CH4 close to or even beat the 2008 trade-off curves. In which, the HBIN-Is showed a remarkable CO2/CH4 selectivity of 73.8, and the HSBI-Is demonstrated a remarkable O2/N2 selectivity of 10.4 at −20 °C due to the sharply increased diffusion selectivity. Both polymer membranes showed excellent plasticization resistance up to 25 bar upstream pressure, endowing the polymerization method and the hydroxyl functionalized intrinsic microporous polymers of great potential in real gas separation applications.

Lipase B Catalysed Condensation Reactions: Water Mediated Chemo-Enzymatic Synthesis of Different Heterocycles

Lipase B Catalysed Condensation Reactions: Water Mediated Chemo-Enzymatic Synthesis of Different Heterocycles

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In this paper, an efficient protocol of DMAP (2‐dimethylaminopyridine)‐catalyzed condensation reaction of readily available α‐bromocinnamaldehydes with 2‐aminobenzimidazoles or 2‐aminoimidazoles in the presence of TBHP was developed. A variety of pyrimido[1,2‐a]benzimidazoles or imidazo[1,2‐a]pyrimidines were constructed in moderate to good yields. More details are discussed in the article by Liu et al. on page 1595–1599.image

DMAP‐Catalyzed C—N Bond Formation for Diverse Synthesis of Imidazo[1,2‐a]pyrimidine and Pyrimido[1,2‐a]benzimidazole Derivatives

Summary of main observation and conclusionA DMAP (2‐dimethylaminopyridine)‐catalyzed condensation reactions for the successful direct construction of pyrimido[1,2‐a]benzimidazole or imidazo[1,2‐a]pyrimidine has been developed. The method utilizes readily available α‐bromocinnamaldehydes with 2‐aminobenzimidazole or 2‐aminoimidazole as starting materials in the presence of 2‐DMAP/TBHP. In the process, two C—N bonds were successfully constructed to synthesize target compounds. The current method features wide substrate scope, product diversification, and metal‐free conditions.

An E1‐Catalyzed Chemoenzymatic Strategy to Isopeptide‐N‐Ethylated Deubiquitylase‐Resistant Ubiquitin Probes

AbstractTriazole‐based deubiquitylase (DUB)‐resistant ubiquitin (Ub) probes have recently emerged as effective tools for the discovery of Ub chain‐specific interactors in proteomic studies, but their structural diversity is limited. A new family of DUB‐resistant Ub probes is reported based on isopeptide‐N‐ethylated dimeric or polymeric Ub chains, which can be efficiently prepared by a one‐pot, ubiquitin‐activating enzyme (E1)‐catalyzed condensation reaction of recombinant Ub precursors to give various homotypic and even branched Ub probes at multi‐milligram scale. Proteomic studies using label‐free quantitative (LFQ) MS indicated that the isopeptide‐N‐ethylated Ub probes may complement the triazole‐based probes in the study of Ub interactome. Our study highlights the utility of modern protein synthetic chemistry to develop structurally and new families of tool molecules needed for proteomic studies.

An E1-Catalyzed Chemoenzymatic Strategy to Isopeptide-N-Ethylated Deubiquitylase-Resistant Ubiquitin Probes.

Triazole-based deubiquitylase (DUB)-resistant ubiquitin (Ub) probes have recently emerged as effective tools for the discovery of Ub chain-specific interactors in proteomic studies, but their structural diversity is limited. A new family of DUB-resistant Ub probes is reported based on isopeptide-N-ethylated dimeric or polymeric Ub chains, which can be efficiently prepared by a one-pot, ubiquitin-activating enzyme (E1)-catalyzed condensation reaction of recombinant Ub precursors to give various homotypic and even branched Ub probes at multi-milligram scale. Proteomic studies using label-free quantitative (LFQ) MS indicated that the isopeptide-N-ethylated Ub probes may complement the triazole-based probes in the study of Ub interactome. Our study highlights the utility of modern protein synthetic chemistry to develop structurally and new families of tool molecules needed for proteomic studies.

Synthesis, characterization, antioxidant and antimicrobial activities of starch aldehyde-quercetin conjugate

In this study, corn starch was functionalized with quercetin. Starch was first oxidized by sodium periodate to produce starch aldehyde, and then starch aldehyde was conjugated with quercetin through acid catalyzed condensation reaction. The structure, antioxidant and antimicrobial activities of starch aldehyde-quercetin conjugate were evaluated. Thin layer chromatography confirmed the conjugate did not contain free quercetin. The UV–vis spectrum of the conjugate exhibited an absorption band at 320 nm. Fourier-transform infrared and proton nuclear magnetic resonance spectra of the conjugate confirmed the aldehyde groups of starch aldehyde were involved in the conjugation reaction. X-ray diffraction pattern revealed the conjugate was in the amorphous state. Scanning electron microscopy observation showed the conjugate had sheet-like, virgate and round shapes. The structure of starch aldehyde-quercetin conjugate was different from that of native starch and starch aldehyde. As compared with native starch and starch aldehyde, starch aldehyde-quercetin conjugate exhibited higher reducing power, free radical scavenging activity and antimicrobial activity against Escherichia coli, Staphylococcus aureus, Salmonella and Listeria monocytogenes. Our results suggested starch aldehyde-quercetin conjugate could be developed as an antioxidant and antimicrobial agent in food industry.

Versatile cis-isoprenyl Diphosphate Synthase Superfamily Members in Catalyzing Carbon–Carbon Bond Formation

Isoprenyl diphosphate synthases (IDSs) catalyze condensation reactions of isoprene units to produce isoprenoids or terpenoids, the largest class of natural products on earth. IDSs are divided into ...

Studying catalytic activity of ternary mixed‐metal Keggin H7SiV3W9O40as a versatile acid catalyst for the synthesis of β‐acetamido ketones

One‐pot four‐component condensation of an aromatic aldehyde with an enolisable ketone and acetyl chloride is investigated in the presence of H7SiV3W9O40in acetonitrile. The prepared catalyst was characterized by standard techniques such as XRD, SEM, and FT‐IR to verify the Keggin structure of nanocatalyst. Furthermore, findings revealed a very good catalytic activity for the applied vanadium substituted heteropolyacid in this acid catalyzed condensation reaction. A series of Keggin Si and V‐substituted heteropolyacids were compared for the synthesis of β‐acetamido‐β‐(4‐chlorophenyl)propiophenone, which showed a better catalytic activity for H7SiV3W9O40and H4SiW12O40than the lacunary and mixed metal Keggin H4SiW9Mo3O40and H5SiW9Mo2VO40. In addition, effect of the nitrilating agent was also demonstrated in this catalytic system and findings show less proficiency for PhCN compared to acetonitrile. Moreover, propiophenone as an α‐substituted enolisable ketone was reacted with some aromatic aldehydes and the anti isomer is detected as the major diastereomer. Therefore, H7SiV3W9O40can be introduced as a new effective, inexpensive, and eco‐friendly catalyst for the introduced four‐component condensation reaction.

Computational Insight into the Mechanism of Ruthenium(II)-Catalyzed α-Alkylation of Arylmethyl Nitriles Using Alcohols.

The ruthenium(II)-catalyzed α-alkylation reaction of arylmethyl nitriles (phenylacetonitrile) using alcohols (ethanol) in toluene has been extensively investigated by means of SMD-M06-2X/6-311G(d,p)-LANL2dz (LAnL2dz for Ru, 6-311G(d,p) for other atoms) calculations. Detailed mechanistic schemes have been proposed and discussed. The catalytically active Ru(II) complex was generated by the base-induced KCl elimination from the catalyst precursor [(PNPPh)RuHCl(CO)]. The overall Ru(II) catalytic cycle consists of three basic processes: (1) ethanol-to-aldehyde transformation catalyzed by the 16-electron unsaturated ruthenium pincer catalyst; (2) a 16-electron unsaturated ruthenium pincer catalyst catalyzed condensation reaction of arylmethyl nitrile with aldehyde, which leads to PhC(CN)=CHCH3; (3) hydrogenation of PhC(CN)=CHCH3, which leads to the formation of the α-alkylated arylmethyl nitrile product (PhCH(CH2CH3)CN). The DFT results revealed that the rate-determining barrier of the overall reaction was 23.9 kcal/mol of the H-transfer step in the third process. The reaction of PhC(CN)=CHCH3 with the dihydride Ru complex, which is generated in the ethanol-to-aldehyde transformation process, is the more preferable hydrogenation mechanism than hydrogenation of vinyl nitrile-Ru complex by H2. Using alcohol as the reactant not only fulfills the requirement of the borrowing-H strategy but also lowers the barriers of the H-migration steps.