Reaction Of Acetate Research Articles

Tropylium Ion, an Intriguing Moiety in Organic Chemistry.

The tropylium ion is a non-benzenoid aromatic species that works as a catalyst. This chemical entity brings about a large number of organic transformations, such as hydroboration reactions, ring contraction, the trapping of enolates, oxidative functionalization, metathesis, insertion, acetalization, and trans-acetalization reactions. The tropylium ion also functions as a coupling reagent in synthetic reactions. This cation's versatility can be seen in its role in the synthesis of macrocyclic compounds and cage structures. Bearing a charge, the tropylium ion is more prone to nucleophilic/electrophilic reactions than neutral benzenoid equivalents. This ability enables it to assist in a variety of chemical reactions. The primary purpose of using tropylium ions in organic reactions is to replace transition metals in catalysis chemistry. It outperforms transition-metal catalysts in terms of its yield, moderate conditions, non-toxic byproducts, functional group tolerance, selectivity, and ease of handling. Furthermore, the tropylium ion is simple to synthesize in the laboratory. The current review incorporates the literature reported from 1950 to 2021; however, the last two decades have witnessed a phenomenal upsurge in the utilization of the tropylium ion in the facilitation of organic conversions. The importance of the tropylium ion as an environmentally safe catalyst in synthesis and a comprehensive summary of some important reactions catalyzed via tropylium cations are described.

Synthesis of 5-Hydrazino-2-cyclopentenone Derivatives by a Gold(I)-Catalyzed Cycloisomerization/Hetero-Diels-Alder/Ring-Opening Tandem Reaction of Enynyl Acetates.

A highly efficient, one-pot synthesis of ring-fused 5-hydrazino-2-cyclopentenone derivatives is achieved by a gold(I)-catalyzed cycloisomerization/hetero-Diels-Alder/ring-opening tandem reaction of suitable enynyl acetates. By mixing the latter with a dialkylazodicarboxylate in the presence of a gold(I) catalyst, the 1,3-acyloxy migration/Nazarov cyclization process leads to dienyl acetate intermediates which are trapped by the heterodienophile present in situ. This provides strained intermediates which undergo highly regioselective ring opening by a retro aza-Michael reaction promoted by traces of water, eventually yielding the target compounds. Six- and seven-membered ring-fused cyclopentenones and piperidine- and tetrahydropyran-fused cyclopentenones bearing a pendant hydrazino functionality on a bridgehead carbon atom can be obtained in high yield (68-96%) by this approach.

Synthesis of Chiral Tricyclic Pyrone Molecules via Palladium(0)-Catalyzed Displacement Reactions of Chiral Tricyclic Pyrone Acetate With Azide or Amine.

Tricyclic pyrone (TP) molecules have shown protection of MC65 neuroblastoma cells death induced by amyloid-β proteins through SβC gene, a decrease of amyloid-β peptide levels, and improvement of motor functions and memory in Alzheimer's disease mouse and rat models. Mechanistic studies suggest TP molecules modulate N-methyl-D-aspartate receptor. A short synthesis of chiral TP analogs was sought using a Pd(0)-catalyzed displacement of TP allylic acetate intermediate with sodium azide or substituted benzylamines. A three-step sequence of reactions by the treatment of 2-{(5aS,7S)-3-methyl-1-oxo-1,5a,6,7,8,9-hexahydropyrano[4,3-b]chromen-7-yl}allyl acetate (9) with (Ph3P)4Pd and sodium azide, followed by reduction with Zn-NH4OCHO and coupling with 3-fluoro-4-hydroxybenzaldehyde and NaCNBH3 was found to give TP coupling molecule, (5aS,7S)-7-(1-(3-fluoro-4-hydroxybenzylamino)prop-2-en-2-yl)-3-methyl-6,7,8,9-tetrahydropyrano[4,3-b]chromen-1(5aH)-one (2), in a good yield. An alternative shorter pathway - a two-step sequence of reactions - by the displacement of 9 by 4-(t-butyldimethylsilyloxy)-3-fluoro-benzylamine with a catalytic amount of (Ph3P)4Pd in THF followed by removal of the silyl ether protecting group gave 2, albeit in a lower chemical yield. The described syntheses should provide general procedures for the synthesis of a library of TP molecules for the discovery of anti-Alzheimer drugs.

Efficient and Low-Impact Acetalization Reactions in Deep Eutectic Solvents.

The synthesis of acetals in acidic natural deep eutectic solvents (NADES), in which the solvent itself participates in the catalytic promotion of the reaction, is reported herein. The reaction is performed under feasible conditions, open air, without the need of external additives, catalysts or water-removing techniques, and it is wide in scope. The products are easily recovered, and the reaction medium is fully recycled and reused without weakening of its catalytic activity after 10 times. Remarkably, the entire process has been realized on gram scale.

Design and Facile Synthesis of Spiro-s-tetrazine Derivatives of 2,4- diphenyl-3-azabicyclo[3.3.1]nonane-9-one.

Literature survey suggested various methods of synthesis of the 3- azabicyclo [3.3.1] nonanes which include, Mannich reaction, α, α'-Annelation of Cyclic Ketones or through Enamines, Michael addition, Intramolecular Cyclizations, etc. However, a mechanism following a Michael addition path through the formation of the dibenzylidene cyclohexanone intermediate can not be ignored. Thus to ensure the mechanistic pathway for the formation of 2,4-diphenyl- 3-azabicyclo[3.3.1]nonan-9-one and to understand the reactivity of a conformationally and biologically important molecule for the synthesis of spiro-s-tetrazine derivatives and its further functionalization with thiazole and thiazolidinone derivatives the present work has been undertaken. Direct reaction of dibenzylidene cyclohexanone and ammonium acetate has been tried to get the confirmation of Mannich/ Michael reaction pathway for the formation of 2,4-diphenyl-3- azabicyclo[3.3.1]nonan-9-one. Synthesis of the spiro-s-tetrazine derivative has been accomplished by the simple condensation reaction of azabicyclic system and thiocarbohydrazide (TCH). Simple methods have been adopted for the installation of heterocyclic moieties like thiazolidinone, thiazole. Failure of the attempts to prepare 2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-onedirectly from dibenzylidene cyclohexanone ruins the possibility of Michael addition reaction and supports the formation of the product through Mannich reaction. Synthesis of the spiro derivatives containing tetrazine, thiazole, thiazolidinone moieties were achieved by using simple techniques and products were obtained in good yield. FTIR, NMR spectroscopy are used for the characterization of all the molecules. Formation of 2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-onewas confirmed by using some additional data like mass and single crystal XRD. Confirmation of the mechanistic route for the 2 2,4-diphenyl-3- azabicyclo[3.3.1]nonan-9-one was achieved and simple methods for the formation of spiro derivatives containing tetrazine, thiazole, thiazolidinone were established.

The tannic acid–based iron nanoparticle: A capable nanocatalyst for the green synthesis of polyhydroquinolines

The tannic acid–based iron nanoparticle (TAN-Fe-NP) was prepared by a redox reaction between tannic acid and FeCl3 in water and characterized by the Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, energy dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Then, a TAN-Fe-NP nanocatalyst was used as an efficient catalyst for the synthesis of polyhydroquinolines from the reaction of ethyl acetoacetate, benzaldehydes, dimedone, and ammonium acetate in ethanol at 60 °C in high yields and low reaction times. Since this catalyst is made of natural materials, it has a great advantage compared with the other catalysts and is cheap, available, natural, safe, nontoxic, and eco-friendly as well.

Preparation of ZSM-5 zeolites by sodium-free method in rotating packed bed

In industry, H-type zeolites are usually synthesized under hydrothermal conditions in the sodium-containing system, in which great deal of ammonia nitrogen wastewater will be produced during the transformation of zeolites from Na-type to H-type. In this work, we prepared ZSM-5 zeolites in the sodium-free system using organic amines in a rotating packed bed (RPB), which can greatly reduce the amount of wastewater. It was found that the ZSM-5 zeolites synthesized by isopropanolamine (MIPA) had the highest acid amount with a value of 2.331 mmol/g compared to that by other three amines, and exhibits the highest conversion of benzaldehyde with a value of 77.63% in the acetal reaction of benzaldehyde and ethylene glycol. More importantly, RPB premixing can improve the transfer of Al into the framework of ZSM-5 zeolites relative to conventional stirring technique. This work provided a new route to prepare ZSM-5 zeolites with high acid amount in sodium-free system.

Investigation of the effect of chelating nitrogenous bases on click reactions on poly[(methyl acrylate)‐co‐(5‐azido‐1‐pentene)

AbstractClick reactions on poly[(methyl acrylate)‐co‐(5‐azido‐1‐pentene)], synthesized by radical polymerization of methyl acrylate and 1‐bromo‐5‐pentene, and converted into the click‐ready azido form by nucleophilic substitution with sodium azide, were studied. Propargyl benzoate and propargyl acetate were clicked onto the polymeric substrate, with the latter known to be a poor click reactant. The impact of solvents (dimethyl formamide (DMF) and tetrahydrofuran (THF)), catalytic systems (CuSO4/Na ascorbate, [Cu(BPMEN)(ClO4)2]/Na ascorbate, bromotris(triphenylphosphine) copper(I) ([CuBr(PPh3)3])) and the addition of chelating nitrogenous bases (triethylamine (TEA), diisopropylethylamine, N,N,N′,N″,N″‐pentamethyldiethylenetriamine) on the degree of conversion was analyzed. Only reactions catalyzed with [CuBr(PPh3)3] led to high or complete conversions in both solvents. Reactions catalyzed with the pre‐catalyst complexes CuSO4⋅5H2O and [(CuBPMEN)(ClO4)2], which require the in situ reduction of Cu(II) to Cu(I) by sodium ascorbate, yielded incomplete conversions in both solvents. Adding chelating nitrogenous bases, with TEA being the most effective, yielded complete conversions for propargyl benzoate with all three catalytic systems in DMF. Adding TEA to reactions of propargyl acetate in DMF increased conversion by 17.9% for CuSO4⋅5H2O/Na ascorbate and 29.6% for [(CuBPMEN)(ClO4)2]/Na ascorbate. The addition of chelating bases was more effective in DMF than in THF, which was also the less suited solvent in reactions without chelating bases. The results show that click reactions with propargyl reagents that cannot increase the nucleophilicity of the vinylidene‐like β‐carbon through electron conjugation yield lower conversions. The effectiveness of catalytic systems that undergo in situ reductions can be enhanced by nitrogenous chelating bases that stabilize the Cu(I) stage. © 2023 Society of Industrial Chemistry.

Zinc-Based Tannin-Modified Composite Microparticulate Scaffolds with Balanced Antimicrobial Activity and Osteogenesis for Infected Bone Defect Repair.

Treatment of infected bone defects is a major clinical challenge; bioactive materials combining sufficient antimicrobial activity and favorable osteogenic ability are urgently needed. In this study, through a facile one-pot hydrothermal reaction of zinc acetate in the presence of tannic acid (TA), with or without silver nitrate (AgNO3 ), is used to synthesize a TA or TA and silver nanoparticles (Ag NPs) bulk-modified zinc oxide (ZnO) (ZnO-TA or ZnO-TA-Ag), which is further composited with zein to fabricate porous microparticulate scaffolds for infected bone defect repair. Bulk TA modification significantly improves the release rate of antibacterial metal ions (Zn2+ release rate is >100 times that of ZnO). Fast and long-lasting (>35 d) Zn2+ and Ag+ release guaranteed sufficient antibacterial capability and excellent osteogenic properties in promoting the osteogenic differentiation of bone marrow mesenchymal stem cells and endogenous citric acid production and mineralization and providing considerable immunomodulatory activity in promoting M2 polarization of macrophages. At the same time, synchronously-released TA could scavenge endogenous reactive oxygen species (ROS) and ROS produced by antibacterial metal ions, effectively balancing antibacterial activity and osteogenesis to sufficiently control infection while protecting the surrounding tissue from damage, thus effectively promoting infected bone defect repair.

Ag/CdO/Fe3O4@MWCNTs Promoted Green Synthesis of Novel Triazinopyrrolothiazepine: Investigation of Antioxidant and Antimicrobial Activity

In this study a new, economical and green method was reported for the synthesis of Ag/CdO/Fe3O4@multi-walled carbon nanotubes (MWCNTs) MNCs as a new heterogeneous catalyst. For confirming the structure of synthesized nanocatalyst, XRD, FESEM, Energy-dispersive X-ray Spectroscopy (EDX), and TEM analyses were utilized. The Ag/CdO/Fe3O4@MWCNTs MNCs as a high-performance catalyst was employed for the preparation of a new family of substituted triazinopyrrolothiazepine using the one-pot condensation reactions of isatoic anhydride, ammonium acetate, α-haloketones, ethyl bromopyruvate, isothiocyanates, and hydrazoyl chloride in water at room temperature. Another work in this research is investigation of antioxidant property of some synthesized compounds by diphenyl-picrylhydrazine (DPPH) radical trapping experiment. Presently, bacteria that are not destroyed with drug have generated many problems in the performance of many transferable diseases. For this reason, discovering appropriate and new procedures for the dealing with these pathogens are important and recent study has focused on the investigation of the antibacterial effects on the prepared compounds.

Microwave-assisted valorization of glycerol to solketal using biomass-derived heterogeneous catalyst

The increase in biodiesel production worldwide makes valorisation of the by-product of this process (glycerol) essential for economic sustainability. Hence, conversion of bioglycerol to platform chemicals such as (2,2-dimethyl-1,3-dioxolan-4-yl)methanol (solketal), a fuel additive, is highly desirable. In this study, glycerol is converted to solketal using a sulfonic acid-functionalized aromatic carbonaceous material (SAFACAM) bearing ancillary hydrophilic groups and acting as a heterogeneous catalyst under microwave irradiation. For the production of solketal by acetalization, an optimal glycerol:acetone molar ratio of 1:5 was recorded. Using a catalyst dosage of 8 wt% at 70 °C for just 10 mins under microwave irradiation (50 W, 100 psi) returned a 98.1 ± 0.4 % conversion of bioglycerol with 100 % selectivity to solketal. The activation energy of the acetalization reaction was determined to be 35.8 kJ mol−1. Catalyst recovery was probed over six cycles, with a modest loss in activity (82.3 ± 0.2 % conversion in the sixth cycle) resulting from limited active site leaching, as confirmed by EDS data.

Synthesis, characterization, and antibacterial activity of anion-depended Cu(II)-Niacinamide complexes

This study aims to prepare different types of Cu(II)-niacinamide complexes by layered solution method from various source of Cu(II) salts (sulphate, nitrate, chloride, and acetate) and in various M(II):niacinamide molar ratio (1:2, 1:4, and 1:6). The complexes were characterized by infrared spectroscopy, melting point test, powder-XRD, anion qualitative test, and scanning electron microscopy. The antibacterial activities of those complexes were also explored. Experimental data reveals that anion of the Cu(II) affects the crystallization of Cu(II)-niacinamide complex, in which various shape and type of solid products were formed, namely light blue hair-like crystals (sulphate), dark green block crystals (acetate), and turquoise sword-like microcrystalline (chloride). These three anions act either as free ion in the crystal lattice (chloride) or as ligand (sulphate and acetate). Based on the characterization, the crystals obtained from the sulphate, chloride, and acetate reactions were predicted to be complexes of [Cu(L)x(SO4)], [Cu(L)x]Cl2, and [Cu2(L)4(CH3COO)2], respectively, where L ​= ​niacinamide. Furthermore, antibacterial test of the three complexes towards E. coli and S. aureus shows that the complexes have better activity than that of the free niacinamide.

"One-Pot" In Situ Tandem Reaction─Dy(III) Coordination-Catalyzed Multicomponent Condensation of Salicylaldehyde Derivatives to Obtain Ketals.

It is difficult to subject simple reaction starting materials to a "one-pot" in situ tandem reaction without post-treatment under mild reaction conditions to obtain multimers with complex structural linkages. In organic synthesis, acetal reactions are often used to protect derivatives containing carbonyl functional groups. Therefore, acetal products tend to have very low stability, and performing multi-step condensation to obtain complex multimeric products is difficult. Herein, we achieved the first efficient multiple condensation of o-vanillin derivatives using Dy(OAc)3·6H2O undergoing a "one-pot" in situ tandem reaction under mild solvothermal conditions to obtain a series of dimers (I and II, clusters 1 and 2) and trimers (I and II, clusters 3 and 4). When methanol or ethanol is used as the solvent, the alcoholic solvent participates in acetal and dehydration reactions to obtain dimers (I and II). Surprisingly, when using acetonitrile as the reaction solvent, the o-vanillin derivatives undergo acetal and dehydration reactions to obtain trimers (I and II). In addition, clusters 1-4 all showed distinct single-molecule magnetic behaviors under zero-field conditions. To the best of our knowledge, this is the first time that multiple acetal reactions catalyzed by coordination-directed catalysis under "one-pot" conditions have been realized, opening a new horizon for the development of fast, facile, green, and efficient synthetic methods for complex compounds.

Transition Metal-Promoted Carbon-Silicon Solid Acid Catalysts for the Synthesis and Process Optimization of Benzaldehyde Glycol Acetal.

A series of transition metal (M)-promoted carbon-silicon (C-M-Si; M=Mn, Fe, Co, Ni, Cu, Zn, Zr) solid acid catalysts with designated molar ratio of M/Si=1 : 8 were fabricated and exploited for acetalization of benzaldehyde (BzH) with ethylene glycol (EG). The physical and chemical properties of these C-M-Si catalysts prepared by sol-gel method were characterized by various techniques, namely, SEM, EDS, TGA-DTG, BET, XRD, FTIR, XPS, and NH3 -TPD. Among various examined acidic C-M-Si catalysts, the C-Fe-Si catalyst exhibited the optimal catalytic activity with the benzaldehyde glycol acetal (BEGA) yield of 97.67 %, in excellent agreement with the value (97.88 %) predicted by the response surface methodology (RSM) based on a Box-Behnken design (BBD). C-Fe-Si catalyst with the high catalytic activities and excellent stability and reusability may be ascribed to the suitable acidity and uniform surface distribution of active sites requisite for the acid-catalyzed acetalization reaction.

Anti-inflammatory, analgesic and antitubercular activity of 4,6-diphenyl-4,5,6,7-tetrahydro-3-selena-1,2,5-triazo-indene derivatives

Several 4,6-diphenyl-4,5,6,7-tetrahydro-3-selena-1,2,5-triazo-indene derivatives have been synthesized by the Mannich reaction (condensation) of ethyl methyl ketone, substituted aldehyde and ammonium acetate and selenium dioxide. The chemical structures have been confirmed by means of IR, 1H NMR and mass spectral data. The synthesized compounds have been evaluated for anti-inflammatory, analgesic and antitubercular activity. The compounds have emerged as the most promising active compounds to that of standards. In addition, the inhibition effect increases with the increase in concentration of these compounds.

Design of Reaction Region of Reactive Dividing Wall Column Based on Cross-Wall Heat Transfer

The reactive dividing wall column (RDWC) is a column structure that couples a reactive distillation and dividing wall column. It has become a research hotspot because of its remarkable advantages in energy consumption. Most RDWCs ignore the possibility of cross-wall heat transfer. For the RDWC, the effect of reaction heat is also ignored. In this work, the reaction of methyl acetate with butanol was studied, and Aspen is used to study the effect of the reaction heat and reaction region length on the cross-wall heat transfer. The results show that compared with the RDWC with an adiabatic cross-wall, the RDWC with cross-wall heat transfer can save 3.2% energy. Cross-wall heat transfer could achieve reactants conversion of 99.4%. From the perspective of energy saving maximization, the double reaction region is set. The research results show that the RDWC with cross-wall heat transfer in the double reaction region can save 4.2% energy compared with the cross-wall insulation.

A facile and scalable strategy for constructing Janus cotton fabric with persistent antibacterial activity

Natural cotton fibers have attached considerable attention due to their excellent wearing comfort, breathability and warmth. However, it remains a challenge to devise a scalable and facile strategy to retrofit natural cotton fibers. Here, the cotton fiber surface was oxidized by sodium periodate with a mist process, then [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) was co-polymerized with hydroxyethyl acrylate (HA) to obtain an antibacterial cationic polymer (DMC-co-HA). The self-synthesized polymer was covalently grafted onto the aldehyde-functionalized cotton fibers via an acetal reaction between hydroxyl groups of the polymer and aldehyde groups of the oxidized cotton surface. Finally, the resulted Janus functionalized cotton fabric (JanCF) revealed robust and persistent antimicrobial activity. The antibacterial test showed that when the molar ratio of DMC/HA was 50: 1, JanCF possessed the best BR (bacterial reduction) values of 100 % against Escherichia coli and Staphylococcus aureus. Furthermore, the BR values could be maintained over 95 % even after the durability test. In addition, JanCF exhibited excellent antifungal activity against Candida albicans. The cytotoxicity assessment confirmed that JanCF exhibited a reliable safety effect on human skin. Particularly, the intrinsic outstanding characteristics (strength, flexibility, etc.) of the cotton fabric were not considerably deteriorated compared to the control samples.

Reactions of Cyclic Acetals with Organoelement Compounds

Reactions of Cyclic Acetals with Organoelement Compounds

Enantioselective Mukaiyama-Michael Reaction of β,γ-Unsaturated α-Keto Esters with Silyl Ketene Acetals Catalyzed by a Chiral Magnesium Phosphate.

We would like to describe an efficient and highly enantioselective Mukaiyama-Michael reaction of silyl ketene acetals with β,γ-unsaturated α-keto esters catalyzed by a chiral magnesium BINOL-derived phosphate. The resulting functionalized 1,5-dicarbonyl adducts are obtained in high yields (up to 96%) and with excellent enantioselectivities (up to 98%) under mild conditions. Two plausible mechanistic pathways were proposed, including a 1,4-addition and a hetero Diels-Alder [4 + 2] cycloaddition.

Stereodivergent Synthesis of Allenes with α,β-Adjacent Central Chiralities Empowered by Synergistic Pd/Cu Catalysis.

The stereodivergent synthesis of allene compounds bearing α,β-adjacent central chiralities has been realized via the Pd/Cu-catalyzed dynamic kinetic asymmetric alkylation of racemic allenylic esters. The matched reactivity of bimetallic catalytic system enables the challenging reaction of racemic aryl-substituted allenylic acetates with sterically crowded aldimine esters smoothly under mild reaction conditions. Various chiral non-natural amino acids bearing a terminal allenyl group are easily synthesized in high yields and with excellent diastereo- and enantioselectivities (up to >20 : 1 dr, >99 % ee). Importantly, all four stereoisomers of the product can be readily accessed by switching the configurations of the two chiral metal catalysts. Furthermore, the easy interconversion between the uncommon η3 -butadienyl palladium intermediate featuring a weak C=C/Pd coordination bond and a stable Csp2 -Pd bond is beneficial for the dynamic kinetic asymmetric transformation process (DyKAT).