Quantitative Yield Research Articles

Ultrasound-Assisted Catalyst-free Synthesis of α,β -Unsaturated Amino Acid Esters and Unsaturated Amino Ketones

Introduction: Sonication has been introduced as a green and effective activation method for the selective monoamination of β-dicarbonyl compounds. The simple one-pot process resulted in different substituted β-amino-ɑ,β-unsaturated esters and ketones at room temperature with quantitative yields. Aqueous NH4OH was used as a safe and economical nitrogen source for pressurized NH3 gas. The process is considered green, accounting for not using any solvents and catalysts, besides some aqueous NH4OH-involved reactions using nontoxic water. A broad variety of useful synthetic intermediates, β- amino-ɑ,β-unsaturated esters and ketones have been prepared in short reaction time. Methods: Using this developed protocol, we were able to synthesize a series of structurally diverse β- amino-ɑ,β-unsaturated esters and unsaturated amino ketones. Results: The synthesis of target compounds was achieved in a truly green process with high atom economy and excellent yields in a catalyst-free one-pot system in an aqueous medium using simple, commercially available, inexpensive ammonium hydroxide as the source of the nitrogen. The high atom economy has been accompanied by the formation of a small amount of nontoxic waste, water. Conclusion: In conclusion, a simple, convenient, and high-yielding catalyst-free environmentally benign method was developed for the synthesis of unsaturated amino acid esters and unsaturated amino ketones.

Catalyst-free synthesis of substituted benzimidazoles and benzothiazoles in a sustainable solvent

A catalyst-free synthesis of various 2-alkyl or aryl-substituted benzothiazoles and benzimidazoles has been developed at room temperature by simply combining alkyl or arylaldehydes with ortho-phenylenediamines and 2-aminothiophenols, respectively. The synthesis of these widely applicable fused heterocycles is often challenging and requires additives. The advantages of this new benign procedure include: products with nearly quantitative yields, high atom economy and no toxic waste formation, catalyst-free process with no need for catalyst separation and/or recycling, the use of a green and sustainable solvent, ethanol, and mostly room temperature reactions with moderate reaction times to ensure that the protocol is energetically favorable.

Simple One-Pot Preparation of Some Highly Electrophilic Haloacetylenes

Preparation of some bis(trialkylstannyl)acetylenes from the corresponding trialkylstannyl chlorides was improved. The tin reagents interact with reactive acid chlorides and bromides to afford intermediate 1-acyl-2-trialkylstannylacetylenes in quantitative yields. The subsequent halogenation performed as a one-pot procedure gives the target 1-acyl-2-haloacetylenes in high yields and provides an effective recycling of the expensive starting trialkylstannyl chlorides.

Synthesis, characterization, and biological activity of cationic ruthenium-arene complexes with sulfur ligands.

Five cationic ruthenium-arene complexes with the generic formula [Ru(SAc)(S2C·NHC)(p-cymene)](PF6) (5a-e) were prepared in almost quantitative yields using a straightforward one-pot, two-step experimental procedure starting from [RuCl2(p-cymene)]2, an imidazol(in)ium-2-dithiocarboxylate (NHC·CS2) zwitterion, KSAc, and KPF6. These half-sandwich compounds were fully characterized by various analytical techniques and the molecular structures of two of them were solved by X-ray diffraction analysis, which revealed the existence of an intramolecular chalcogen bond between the oxygen atom of the thioacetate ligand and a proximal sulfur atom of the dithiocarboxylate unit. DFT calculations showed that the C=S…O charge transfer amounted to 2.4kcalmol-1. The dissolution of [Ru(SAc)(S2C·IMes)(p-cymene)](PF6) (5a) in moist DMSO-d6 at room temperature did not cause the dissociation of its sulfur ligands. Instead, p-cymene was slowly released to afford the 12-electron [Ru(SAc)(S2C·IMes)]+ cation that could be detected by mass spectrometry. Monitoring the solvolysis process by 1H NMR spectroscopy showed that more than 22days were needed to fully decompose the starting ruthenium-arene complex. Compounds 5a-e exhibited a high antiproliferative activity against human glioma Hs683 and human lung carcinoma A549 cancer cells. In particular, the IMes derivative (5a) was the most potent compound of the series, achieving toxicities similar to those displayed by marketed platinum drugs.

Enantioselective Construction of Polycyclic Chromanes through Organocatalytic Sequential Quintuple Reaction via One‐Pot Step‐Wise Procedure

Enantioselective Construction of Polycyclic Chromanes through Organocatalytic Sequential Quintuple Reaction via <scp>One‐Pot Step‐Wise</scp> Procedure

Synthesis of 5-Amino-3(2H)-furanones via S-Methylation/Intramolecular Cyclization of γ-Sulfanylamides.

The S-methylation/intramolecular cyclization of γ-sulfanylamide is depicted. Different methylating reagents were successfully employed for S-methylation, depending on the substituent pattern of the amide in the starting γ-sulfanylamides; trimethyloxonium tetrafluoroborate was used for N-aryl substituted γ-sulfanylamides, and the combination of methyl iodide and silver(I) tetrafluoroborate was used for N-alkyl substituted γ-sulfanylamides. When the resulting sulfonium salt was treated with DBU, it smoothly underwent intramolecular cyclization to produce a series of N-aryl, N-alkyl, N,N-dialkyl or N-alkyl-N-aryl substituted 5-amino-3(2H)-furanones in 55%-quantitative yields.

Deoxygenation of N‐heterocyclic N‐oxides with Selectfluor and disulfane

AbstractHerein, we describe a metal‐free methodology using Selectfluor with disulfane, for the deoxygenation of N‐heterocyclic N‐oxides (33 examples). This effective, robust, and simple methodology enables the synthesis of various deoxygenated analogues from a wide range of N‐heterocyclic N‐oxide cores at room temperature in short reaction times with quantitative yields.

Gallium Hydride-Catalyzed Selective Hydroboration of Unsaturated Organic Substrates.

The first examples of tetrasubstituted conjugated bis-guanidinate (CBG) supported monomeric and thermally stable gallium dihalides [LGaX2], (X=Cl (Ga-Cl), I (Ga-I)) and dihydride (Ga-H) [LGaH2] (where L={(ArHN)(ArN)-C=N-C=(NAr)(NHAr)}; Ar=2,6-Et2-C6H3) compounds are reported. The reaction of in situ generated LLi with 1.0 equiv. GaX3 (X=Cl, I) afforded compounds Ga-Cl and Ga-I. The reaction between Ga-Cl and Li[HBEt3] in benzene yielded the dihydride compound Ga-H. All reported compounds (Ga-Cl, Ga-I, and Ga-H) were characterized by NMR, HRMS, and single-crystal X-ray diffraction studies. Ga-H was probed for the hydroboration of carbodiimides (CDI), isocyanates, and isothiocyanates with HBpin. Compound Ga-H was also found effective for the catalytic hydroboration of imines, nitriles, alkynes, esters, and formates, affording the corresponding products in quantitative yields. Stoichiometric reactions with a CDI were performed to establish the catalytic cycle.

Substitution Lability of the Perfluorinated Cp* Ligand in [Rh(COD)(C5(CF3)5)] Towards Triphenylpnictogens EPh3 (E=N, P, As, Sb, Bi).

Triphenylpnictogens EPh3 (E=N, P, As, Sb, Bi) are able to displace the perfluorinated Cp* ligand in [Rh(COD)(C5(CF3)5)] (COD=1,5-cyclooctadiene) in up to quantitative yield. The resulting ionic products contain [C5(CF3)5]- as uncoordinated counter anion. The cations feature [Rh(COD)]+ fragments, coordinated by one (N, Bi), two (P, As) or three (Sb) triphenylpnictogen moieties. Whereas coordination via the pnictogen is observed for P, As and Sb, π-coordination of the aryl rings is observed for N and Bi.

One Precursor, Two Different Outcomes: SnO-Graphite Composite and Anion-Doped SnO2 with Ester Surface Functionality.

The technological importance of SnO2 and SnO has invited scientists to explore various aspects, including their synthesis in the nanosize regime, surface functionalization, and composite formation. In the present work, a binuclear Sn2-EDTA complex has been demonstrated to produce a SnO-graphite composite and C, N-codoped SnO2 nanocrystals with ester functionality in quantitative yields by thermal and solvothermal dissociation processes. The products were characterized extensively. While SnO in the SnO-graphite composite exhibited tetragonal symmetry, graphitic carbon had defects. The composite had 12 wt % of graphitic carbon. The role of the SnO-graphite composite as an anode in lithium-ion batteries (LIB) has been evaluated. Solvothermal dissociation of the Sn2-EDTA complex in a propylene glycol medium yielded nanocrystalline SnO2 with yellow color. Agglomerated crystallites had ester functionality on their surfaces. The surface functionality was thermally stable up to 200 °C, and its complete removal yielded tetragonal white-colored SnO2. Co-doping of carbon and nitrogen in yellow SnO2 reduced its optical band gap (2.9 eV). Despite the negative surface charge of the functionalized SnO2, its affinity to rapidly adsorb anionic azo dyes (Congo red and Eriochrome black T) from aqueous solutions has been validated. Following pseudo-second-order kinetics, adsorption data analysis revealed chemisorption as the primary driving force in this process.

Effect of Potassium Humate, Phosphorus and Copper on Onion Quantitative and Qualitative Yield

Previous research has been limited regarding the combined impacts of copper and potassium humate under various phosphorus fertilization levels on onion crops. So, a field trials were performed during two successive winter seasons of 2021 - 2022 and 2022 - 2023 aiming to evaluate three levels of calcium superphosphate (representing 100 %, 75 % and 50 % of the phosphorus recommended dose) as main plot treatments, along with three levels of potassium humate soil addition ( 0.0 %, 1.0 % and 2.0 % ) as sub-plot treatments. Additionally, foliar spraying of copper was carried out at three different rates (0.0 %, 0.1 % and 0.2 %) as sub-subplot treatments. These factors were examined individually or in combination to assess their impact on onion performance, quantitative yield, and qualitative attributes. Firstly, in terms of the individual effect of phosphorus recommended dose (PRD), the application of 100% of PRD demonstrated superior impacts on onion growth performance, quantitative and qualitative yield compared to 75% and 50% of PRD, respectively. Secondly, focusing on the individual effect of soil addition of potassium humate, all parameters related to growth performance, quantitative and qualitative yield, such as bulb weight and diameter, neck diameter, marketable bulb yield, total dissolved solids (TDS), total sugar (%), carbohydrates, and crude protein, exhibited an increase with higher rates of added potassium humate. Thirdly, the values of all parameters studied increased as the rate of copper application increased, indicating a positive correlation between copper application and onion crop performance. Lastly, the combined treatment of 100% of PRD with 2.0% potassium humate and 0.2% copper recorded the highest values across all measured parameters. Additionally, the combined treatment of 75% of PRD with potassium humate at rates of 1.0% or 2.0%, along with copper at rates of 0.1% and 0.2%, outperformed the individual application of 100% PRD in terms of the measured parameters. Therefore, it can be concluded that the combined addition of potassium humate (as soil addition) and Cu (as foliar application) has a vital role in improving the quantitative and qualitative yield of the as well as raising the efficiency of phosphate fertilizers.

Variability of the component composition of the essential oil of &lt;i&gt;Artemisia salsoloides&lt;/i&gt; Willd. from natural populations of the flora of Dagestan

To study the variability of the gathering locality and componen t composition of essential oil from the aerial part of a little‐studied species – Artemisia salsoloides Willd. depending on abiotic environmental factors, such as height above the level of the place of growth. Aerial parts of A. salsoloides were collected during the flowering phase in four Dagestan natural populations to obtain essential oil using the Clevenger method. To determine the component composition of the samples obtained of essential oils of A. salsoloides, chromatography‐mass spectrometric analysis was used. The components were identified using the NIST08 and FFNSC mass spectral libraries. In total, 55 compounds were identified in the essential oil samples, where monoterpenoids account for 59.92 % – 75.98 % and sesquiterpenoids – for 23.24 % to 37.81 %. At the same time, 15 major compounds were identified. Thus, it should be noted that there was found to be a wide range of values for monoterpenoids: β‐pinene, trans‐β‐ocimene, cis‐alloocimene, benzene, 2,4‐pentadinyl, and among sesquiterpenoids – α‐copaene, β‐sesquiphilandrene, spathulenol. The quantitative yield of essential oil in the studied samples varied from 0.68 % to 1.36 % of airdried raw materials, depending on the growth location of the species. Four separate populations of A. salsoloides were identified by means of cluster analysis based on the component composition of the studied essential oils. For the first time, the composition of the essential oil of the aerial part of wild Dagestan samples of A. salsoloides was studied as depending on an abiotic factor (height above sea level) of the environment. The results obtained of the component composition of the essential oil of A. salsoloides samples showed the presence of a number of valuable compounds, which allow the use of essential oils as their sources.

Ecology, genetic diversity, and population structure among commercial varieties and local landraces of Capsicum spp. grown in northeastern states of India.

Northeastern states of India are known for unique landraces of Capsicum spp. with geographical indications. However, little information is available about these valuable landraces of chillies. Surveys and collections were carried out in niche areas to find out their ecology and diversity through morphological traits and molecular analysis using microsatellite markers. Our result characterized the ecology of niche areas as cool (11.0°C-20.7°C) and humid (>60% relative humidity) climates for dalle-chilli (Capsicum annuum L.); mild-warm (12.2°C-28.6°C) and humid for king-chilli (C. chinense Jacq.); and cool to warm (11.3°C-33.1°C) and humid for bird's eye chilli (C. frutescens L.) during the crop period. The canonical correspondence analysis has shown the significant impact of temperature on the agro-morphological traits and distribution of the landraces in their niche areas. A wide variability was observed for different quantitative traits and yield attributing characters (fruit length, diameter, weight, and yield), showing high heritability (97.0%-99.0%), and genetic advance as a percentage of the mean (119.8%-434.0%). A total of 47 SSR markers used for the molecular analysis generated 230 alleles, ranging from 2 (HPMSE-7) to 10 (HPMSE-5), with an average of 4.89 alleles per locus. The average polymorphism information content was also high (0.61) and ranged from 0.20 (HPMSE-7) to 0.85 (CAMS-91). The observed average heterozygosity was lower than the expected value. Analysis of molecular variance has shown significant variation within (69%) and between (31%) of the populations of Capsicum spp. Based on Nei's genetic distance, bird's eye chilli and king-chilli were found to be closer to each other, whereas dalle-chilli, a tretraploid species, was closer to hot pepper (C. annuum). However, the flower size of dalle-chilli was large and found closer to king-chilli in color and differs from C. chinense due to the presence of calyx teeth. For quality traits, landraces king-chilli, dalle-chilli, and bird's eye chilli have shown 2.8, 2.0, and 1.4 times higher average capsaicin and 0.46, 0.25, and 0.22 times higher average oleoresin content over the hot pepper, respectively. The knowledge of ecology and diversity can be used in identifying new areas for production, selection of elite lines, conservation, and crop improvement.

Effects of Biofertilizers in Improving the Growth and Development of the Traditional Medicinal Plant Aloe vera L. (Aloe barbadensis Miller)

Abstract: Aloe vera L. (Aloe barbadensis Miller) is a very common water deficit-resistant plant which has immense medicinal properties. It is a fleshy plant belonging to the Liliaceae family. Aloe barbadensis has enormous medicinal value. According to historical records, it has been used in folk and traditional medicine in different parts and regions of the world for ages. Aloe vera is widely used in Ayurvedacharya and Unani medicine. The plant is a rich source of potent medicinal phytocomponents, each with pronounced medicinal properties. Primarily, Aloe gel is considered one of Mother Nature’s magical formulations for treating and curing various health ailments, including skin diseases, hair fall, indigestion, inflammation, and many others. Studies revealed that the use of biofertilizers significantly improves the growth and development of the Aloe plant. The quality and quantity of the constituents of Aloe vera gel are also reported to improve significantly with the use of biofertilizers. Biofertilizers, when used alone or in combination, are reported to influence the length, width, biomass, and phytoconstituents of the leaves of the plant. Biofertilizers, which are environment friendly and more effective on Aloe, can thus be considered a better substitute for other fertilizers for boosting the qualitative and quantitative yield of the magical medicinal plant, Aloe barbadensis.

Rapid copper-catalyzed friedel-crafts alkylation of indoles in 25 Minutes

Herein, a protocol for the rapid synthesis of 3,3′-Diindolylmethanes (DIMs) via coppercatalyzed Friedel-Crafts alkylation of indoles in 25 min has been developed. This protocol also has the advantage of H2O as a by-product, room temperature and air condition, prefunctionalization-free of indoles, good C-3 selectivity of indoles, broad substrate scope, good reactivity (TON of up to 19.6, TOF of 972 h-1) and excellent to quantitative yields. Notably, the obtained DIMs 5i (IC50 = 6.709 μM) and 5j (IC50 = 5.699 μM) exhibit good anticancer activities toward MCF-7 cells (human breast cancer cells).

Perfluoroalkylation of Triarylamines by EDA Complexes and Ulterior Sensitized [6π]-Electrocyclization to Perfluoroalkylated Endo-Carbazoles. Mechanistic and Photophysical Studies.

Blue LEDs-irradiation of a mixture of N,N,N',N'-tetramethylethylenediamine (TMEDA) and perfluoroalkyl iodides (RF-I) - Electron Donor Acceptor (EDA)-complex - in the presence of triphenylamines (TPAs) in an aqueous solvent mixture afforded mono-perfluoroalkylated triphenylamines (RF-TPA) in good yields. These RF-TPA were further subjected to acetone-sensitized [6π]-electrocyclization at 315 nm-irradiation affording exclusively perfluoroalkylated endo-carbazole derivatives (RF-CBz) in quantitative yields. Mechanistic studies and photophysical properties of products are studied.

Gold‐Catalyzed Synthesis of Ortho‐Quinone Methide Analogues as Reactive Synthetic Precursors

Abstract2‐Exomethylene indolin‐3‐ones are useful synthetic intermediates with a unique indole scaffold. However, their synthesis has not yet been reported owing to their reactivity and instability. In this study, a gold(I)‐catalyzed method for generating 2‐exomethylene indolin‐3‐one derivatives via the 5‐exo‐dig‐selective cyclization of 2‐(2‐amino)phenyl alkynyl ketones with an alkyne terminus was developed. The subsequent pseudo‐dimerization of the generated 2‐exomethylene indolin‐3‐ones and their [4+2] cyclization reactions with 1,1‐disubstituted alkenes afforded spiropseudoindoxyl and pyranoindole derivatives, respectively, in 21% to quantitative yields. Density functional theory calculations of the gold‐catalyzed cyclization provided insights into the 5‐exo‐dig selectivity. Furthermore, the reactive 2‐exomethylene indolin‐3‐one was isolated for the first time based on the results from 1H NMR spectroscopic monitoring. The isolated product was applied to various transformations. Our synthesis method promotes the development of bioactive agents and functional materials with complex cyclic structures.

Mesoionic N-Heterocyclic Olefins as Initiators for the Lewis Pair Polymerization of Epoxides.

Mesoionic N-heterocyclic olefins (mNHOs) have recently emerged as a novel class of highly nucleophilic and super-basic σ-donor compounds. Making use of these properties in synthetic polymer chemistry, it is shown that a combination of a specific mNHO and a Mg-based Lewis acid (magnesium bis(hexamethyldisilazide), Mg(HMDS)2) delivers poly(propylene oxide) in quantitative yields from the polymerization of the corresponding epoxide (0.1mol% mNHO loading). The initiation mechanism involves monomer activation by the Lewis acid and direct ring-opening of the monomer by nucleophilic attack of the mNHO, forming a zwitterionic propagating species. Modulation of the mNHO properties is thereby a direct tool to impact initiation efficiency, revealing a sterically unencumbered triazole-derivative as particularly useful. The joint application of mNHOs together with borane-type Lewis acids is also outlined, resulting in high conversions and fast polymerization kinetics. Importantly, while molar mass distributions remain relatively broad, indicating faster propagation than initiation, the overall molar masses are significantly lower than found in the case of regular NHOs, underlining the increased nucleophilicity and ensuing improved initiation efficiency of mNHOs.

Site-Specific Conjugation of Native Antibody: Transglutaminase-Mediated Modification of a Conserved Glutamine While Maintaining the Primary Sequence and Core Fc Glycan via Trimming with an Endoglycosidase.

A versatile chemo-enzymatic tool to site-specifically modify native (nonengineered) antibodies is using transglutaminase (TGase, E.C. 2.3.2.13). With various amines as cosubstrates, this enzyme converts the unsubstituted side chain amide of glutamine (Gln or Q) in peptides and proteins into substituted amides (i.e., conjugates). A pleasant surprise is that only a single conserved glutamine (Gln295) in the Fc region of IgG is modified by microbial TGase (mTGase, EC 2.3.2.13), thereby providing a highly specific and generally applicable conjugation method. However, prior to the transamidation (access to the glutamine residue by mTGase), the steric hindrance from the nearby conserved N-glycan (Asn297 in IgG1) must be reduced. In previous approaches, amidase (PNGase F, EC 3.5.1.52) was used to completely remove the N-glycan. However, PNGase F also converts a net neutral asparagine (Asn297) to a negatively charged aspartic acid (Asp297). This charge alteration may markedly change the structure, function, and immunogenicity of an IgG antibody. In contrast, in our new method presented herein, the N-glycan is trimmed by an endoglycosidase (EndoS2, EC 3.2.1.96), hence retaining both the core N-acetylglucosamine (GlcNAc) moiety and the neutral asparaginyl amide. The trimmed glycan also reduces or abolishes Fc receptor-mediated functions, which results in better imaging agents by decreasing nonspecific binding to other cells (e.g., immune cells). Moreover, the remaining core glycan allows further derivatization such as glycan remodeling and dual conjugation. Practical and robust, our method generates conjugates in near quantitative yields, and both enzymes are commercially available.

Synthesis and properties of unsaturated block copolyether ketones

Block-copolyether ketones containing &gt;C=CCl2 groups, characterized by high thermal and mechanical properties, with quantitative yield and high values of reduced viscosity, were obtained based on various oligomers with condensation degrees of n = 1-20 using the method of acceptor-catalytic polycondensation. The structure of the resulting polyesters was confirmed. The kinetics of polyester structuring at the site of the double bond depending on temperature and dwelling time was studied.