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Some Sulfanoquinoxaline-2,3-diones hydrazone derivatives (1-8) were synthesized from the reactions of 2,3-dioxoquinoxaline-6-sulfonohydrazine with seven substituted benzaldehydes and acetophenone. All the synthesized compounds were biologically evaluated against cholinesterase’s (acetylcholinesterase and butyryl cholinesterase). Compounds 1-8 were found to be a good selective inhibitor for acetylcholinesterase and butyryl cholinesterase. Among the series, compounds 3 (IC50 = 75 ± 10 µg/mL) and 5 (IC50 = 80 ± 10 µg/mL) were found to be the most active inhibitors against acetylcholinesterase, while compounds 6 (IC50 = 110 ± 10 µg/mL), 8 (IC50 = 130 ± 10 µg/mL) and 7 (IC50 = 150 ± 10 µg/mL), were found to be most active inhibitor against butyryl cholinesterase. The IC50 values for all the synthesized compounds were lower than standard, eserine (IC50 = 70 ± 20 µg/mL). Their considerable acetylcholinesterase and butyryl cholinesterase inhibitory activities make them a good candidate for the development of selective acetylcholinesterase and butyryl cholinesterase inhibitors.

Aims: To synthesize some phthalimides derivatives and evaluate the compounds for their possible biological properties. Methods: The substituted phenylisoindoline-1,3-dione were synthesized from the reactions of N-phenyl phthalimide with different substituted aromatic aldehyde. The synthesized compounds were characterized using nuclear magnetic resonance spectroscopic analysis. The acetylcholinesterase and butyryl cholinesterase inhibitions were determined by Spectro photochemical analysis of acetylthiocholine and butyryl choline chloride. Results: Compounds 6 (IC50 = 30±3 µg/mL) and 4 (IC50 = 141±60 µg/mL) were found to be the most active inhibitors against acetylcholinesterase, while compounds 4 (IC50 = 102±10 µg/mL), 5 (IC50 = 105 ± 20 µg/mL) and 2 (IC50 = 190 ± 10 µg/mL), were found to be most active inhibitor against butyryl cholinesterase. Conclusion: The considerable acetylcholinesterase and butyryl cholinesterase inhibitory activities of the synthesized compounds makes them good candidates for the development of selective acetylcholinesterase and butyryl cholinesterase inhibitors.

Aims: This studies aims at the synthesis of new heterocyclic systems and study its biological and pharmacological properties. Objective: This study was designed to synthesized some quinoxaline-2,3-dione with sulfonamide moiety, characterize the synthesized compounds, and study the antimicrobial properties of the synthesized compounds on some bacterial strains. Materials and Methods: Six quinoxaline-6-sulfonohydrazone derivatives were synthesized by reacting quinoxaline-6-sulfonohydrazine with some substituted benzaldehydes and ketones. The compounds were tested for their potential antibacterial properties. Results: All the test compounds possessed promising antibacterial property against a panel of bacterial strains used for this study. The MIC values exhibited by these compounds ranged between 0.0313 and 0.250 mg/mL. Among the compounds tested, compound 2 showed appreciable antibacterial activity. Discussion and Conclusion: The study concluded that all the compounds exhibited appreciable bactericidal effects towards all the bacterial strains, particularly, compound 2 This is an indication that such compounds possessing broad spectrum activities will be useful in formulating antimicrobial compounds which could be used to treat infections caused by pathogens that are now developing resistance against the available antibiotics.

The review article attempts to give recent advances on quinoxaline and its derivatives. Some pathways to the synthesis of quinoxaline, quinoxaline-2-one and quinoxaline-2,3-dione were reported using simple reactive quinoxaline synthon. In addition, the reactions, biological and technological applications of derivatives of quinoxaline and related compounds were reported.

Aims: This aims of this study was to continue the effort to synthesis new quinoxaline-based heterocycles and study its antibacterial properties. Objective: This study was designed to reacts 3,6-dimethylquinoxaline-2-hydrazine with some substituted aromatic ketones and study their antibacterial properties on some locally and clinically isolated bacterial strains. Materials and Methods: Five 3,6-dimethylquinoxaline-2-hydrazone derivatives were synthesized from the reactions of 3,6-dimethylquinoxaline-2-hydrazine with various substituted aromatic ketones. The products were then tested for their potential antibacterial properties. Results: All the synthesized compounds were found to be active against all the bacterial strains investigated in this study. It was observed that the zones of inhibition observed for the synthesized compounds against the test organisms ranged between 15 mm and 38 mm. The MIC observed for the synthesized compounds ranged between 0.0313mg/mL and 0.125 mg/mL, while that of the standard antibiotic, streptomycin, varied between 0.0313 mg/mL and 0.500 mg/mL and those observed for tetracycline falls between 0.0313 mg/mL and 0.500 mg/mL. The minimum bactericidal concentrations exhibited by the synthesized compounds ranged between 0.0625 mg/mL and 0.250 mg/mL Discussion and conclusion: The study concluded that all the compounds exhibited appreciable bactericidal effects against all the bacterial strains, which is an indication that such synthetic compounds possessed broad spectrum activities and such compounds could be useful in formulation of antibacterial compounds which could be used to mitigates infections caused by pathogens that are now developing resistance against the available antibiotics.

2,3-Dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonohydrazide and its derivatives were synthesized and characterize by IR, 1H-NMR, 13C-NMR and mass spectrometry analytical methods. The 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl hydrazide (compound 1), was synthesized from the reaction of o-phenylenediamine with oxalic acid to obtain quinoxaline-2,3-dione, which was subjected to chlorosulfonation with chlorosulfonic acid to give 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl chloride. The 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl chloride was reacted with hydrazine hydrate to afford 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl hydrazide (compound 1). The quinoxaline-6-sulfonohydrazone derivatives were synthesized by reacting compound 1 with substituted benzaldehydes or aromatic ketones. The chemical structures of the compounds prepared were confirmed by spectral data. The synthetic methodology was efficient and environmentally friendly; this was due to the fact that the work-up stage was carried out in water. Key words: 2,3-Dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl hydrazide, quinoxaline-2,3-dione, synthesis, substituted benzaldehydes, isatin, infrared, spectroscopy.

The growing resistance to the current antimalarial drugs in the absence of a vaccine can be effectively tackled by identifying new metabolic pathways that are essential to the survival of the malaria parasite and developing new drugs against them. Triterpenes and steroids are the most abundant group of natural products with a great variety of biological activities. However, lanosterol is not known to possess any significant biological activity. In this study the binding and interactions of a dinitrophenyl hydrazine (DNP) derivative of lanosterol, LAN (a derivative that incorporates a substantially polar moiety into the steroid) with P. falciparum transketolase was studied by molecular docking and MD simulation with the view to exploit the DNP derivative as a lead in antimalarial chemotherapy development considering that the P. falciparum transketolase (PfTk) is a novel target in antimalarial chemotherapy. The enzyme catalyses the production of ribose sugars needed for nucleic acid synthesis; it lacks a three-dimensional (3D) structure necessary for docking because it is difficult to obtain a crystalline form. A homology model of PfTk was constructed using Saccharomyces cerevisiae transketolase (protein data bank ID of 1TRK) as the template. The compound was observed to have Free Energy of Binding higher than that of the cofactor of the protein (Thiamine Pyrophosphate, TPP) and a synthetic analog (SUBTPP) used as reference compounds after MD Simulation. The compound was synthesized in a two-step, one-pot reaction, utilizing a non-acidic and mild oxidant to oxidize the lanosterol in order to avoid the rearrangement that accompanies the oxidation of sterols using acidic oxidants. The LAN was characterized using IR spectroscopy and NMR experiments and tested in-vivo for its antimalarial chemo suppression using a murine model with Chloroquine as a standard. The LAN at a concentration of 25 mg/kg was found to have a comparable activity with Chloroquine at 10 mg/kg and no mortality was observed among the test animals 24 days post drug administration showing that the compound indeed has potential as an antimalarial agent and a likely inhibitor of PfTk considering that there is a strong agreement between the in-silico results and biological study. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40203-021-00097-8.

Tryptanthrin is a potent natural alkaloid with good in vitro pharmacological properties. Herein, we report the synthesis of the compound via a new method involving the reduction of isatin with solid-state-supported sodium borohydride under microwave irradiation. The title compound has been tested for its analgesic and anti-inflammatory activity. The results showed that tryptanthrin dose dependently inhibits oedema and pain formation in all the models used. The agent also exhibited significant higher effects in its anti-inflammatory and analgesic activities better than positive drugs (aspirin and indomethacin) being currently used in the treatment and in the management of acute and chronic forms of pain and inflammatory disorders. The inhibitory potential of the compound was investigated by molecular docking using the software AutoDock Vina. The docking results were used to better rationalize the action and prediction of the binding affinity of tryptanthrin. Density Functional Theory (DFT) calculations at the B3LYP/6-311++G (2df, 2pd) level of theory showed that compared to ascorbic acid, tryptanthrin shows higher antioxidant activity which may be improved upon by functionalizing the aromatic core to enhance its solubility in polar solvents. The calculated electronic and thermodynamic properties obtained for tryptanthrin compete well with the standard ascorbic acid., Tryptanthrin; Analgesic and anti-inflammatory activity; Isatin; DFT calculations; Molecular docking; Borohydride reduction.

An attempt to synthesize thioparabanic acid as precursor to other fused heterocyclic compounds, by a microwave assisted multistep one-pot reaction yielded a co-crystal of N-carbamothioylacetamide (NCTA) and N,N′-thiocarbonyldiacetamide (NNTCA) which is being reported in this paper. The structure of N-carbamothioylacetamide and N,N′-thiocarbonyldiacetamide from the attempted synthesis of 1,3-diacetyl-2-thioxoimidazolidine-4,5-dione, C5H8N2O2S.C3H6N2OS, has triclinic (P-1) symmetry. It is of interest with respect to biological application. The structure displays inter- and intra-molecular hydrogen bonding through –C=O···H interactions. Similarly, –C=S···H hydrogen bonding interactions are present, providing additional intermolecular stability to the co-crystal. For application as a potential drug candidate, a density functional theory (DFT) simulation of the antioxidant activities of the co-crystal and its individual components (NCTA and NNTCA) has been performed. The computed redox potentials indicate that the study compounds show comparable antioxidant activities with ascorbic acid (AA) for a one electron transfer process. Meanwhile, for a two-electron process, AA showed significant antioxidant advantage over the titled compound.

ceylan, umit/0000-0002-1461-9889 WOS: 000403855700047 A new crystallographic form of a pure xanthenedione derivative (11'), C22H24O3, was isolated from the hexane extract of the seeds of Garcinia kola. The structure of the compound was determined on the basis of FTIR and NMR spectroscopy and confirmed by single-crystal X-ray diffraction analysis. The compound crystallized as C22H24O3 H2O H3O+ Cl-, as the result of the extraction process, adopts monoclinic, space group P21/n (no. 14) and is stabilized by OW-H center dot center dot center dot OW, OW-H center dot center dot center dot Cl, C-H center dot center dot center dot OW, C-H center dot center dot center dot Cl intramolecular hydrogen bonds and weak OW-H center dot center dot center dot O, C-H center dot center dot center dot O, intermolecular interactions forming a 3-D supramolecular structure. The molecular property of the pure xanthene derivative, C22H24O3, has also been investigated using the density functional theory (DFT) method. The calculated IR, H-1 and C-13 data were found to be in good agreement with experimental values. The compound C22H24O3 showed weak DPPH radical scavenging activity with IC50 value of 2.37 +/- 0.08 mg/ml. (C) 2017 Elsevier B.V. All rights reserved. NSF-MRI programNational Science Foundation (NSF)NSF - Office of the Director (OD) [CHE-1039027] JPJ acknowledges the NSF-MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.

A well-known component of the Indian spice turmeric, curcumin, has received a lot of attention in recent years as a potential antimalarial agent but the inherent problems associated with low bioavailabilty tends to limit its applicability. The bioavailability is linked to its low solubility in water and its rapid break down in the blood plasma. In this study, we have proposed the use of synthetic analogs of curcumin and their derivatives which are expected to be less prone to degradation in the blood plasma as possible antimalarials. The binding affinity of monocarbonyl analogs of curcumin and their 2,4-dinitrophenylhydrazone derivatives for the chain A domain of plasmepsin II, one of the key enzymes involved in hemoglobin digestion in the food vacuole of the malaria parasite was determined by computational docking analysis, performed using Auto Dock Vina 1.1.2, pymol and Chem 3D ultra 12.0. The binding energies of the 20 compounds studied was compared with that of pepstatin A (a known inhibitor of plasmepsin II), curcumin and chloroquine. The 3D structure of the protein was obtained from the protein data bank (PDB ID:1M43), the compounds’ 3D structure was generated with the Chem 3D ultra 12.0 and visualization done with pymol. Out of the 20 compounds docked with plasmepsin II, 17 had binding energies higher than that of pep A (-32.6, kJ/mol) and 19 of the compounds had binding energies higher than that of curcumin (30.96, kJ/mol). The docked compounds, 5b, 6b and 7b had the highest binding energies (-44.73 kJ/mol, -42.64 kJ/mol and -41.80 kJ/mol respectively). It is expected that the compounds with binding energies higher than that of pep A may be considered for further antimalarial studies in-vitro and in-vivo.

Aims: To identify extractable components in the traditional medicinal plant, Bryophyllum pinnatum (BP). Methodology: The leaves of BP were sequentially extracted with non-polar (CH2Cl2) and polar (CH3OH) solvents. The extracts were derivatized to their volatile fatty acid methyl esters (FAME) and trimethylsilyl (TMS) esters/ethers and characterized by gas chromatography mass spectrometry (GC-MS). Results: GC-MS analysis revealed the presence of sterols, fatty acids, monoarylphenolics, sugars, alcohols, sugar alcohols, sugar acids, carboxylic acids, dicarboxylic acids, tricarboxylic acids, vitamin, alkanes and alkenes. Conclusion: Compounds identified (e.g. tocopherol) in the extracts are most likely responsible for its antimicrobial, antifungal, anticancer, antitumour and insecticidal activities. Original Research Article Faboro et al.; EJMP, 14(3): 1-10, 2016; Article no.EJMP.26156 2

WOS: 000424717800065 In the present study a new tetrahydroquinazoline-2-carboxylic, C10H10N2O3, 1', was synthesized and its structure was characterized by elemental analysis, IR, H-1 NMR, C-13 NMR data and high-resolution mass spectrometry. The spectral results are in line with the proposed structure. Single crystal X-ray structural analysis of the compound showed that the crystal structure adopts a monoclinic space group P2(1)/c, with the packing of the molecule stabilized by C=O... ...H-O, N-H....O=C-O-intermolecular hydrogen bonding. The theoretical geometrical parameters of the compound have been calculated using density functional (DFT) and time-dependent density functional (TD-DFT) theory methods and have been used to predict the thermodynamic one-electron redox potential and the electronic absorption property of the compound. The theoretical characterization matched the experimental measurements, showing a good correlation. The calculated HOMO-LUMO gap (4.79 eV) suggests that compound 1' could be a potential antioxidant The synthesized compound was screened for its in vitro antimicrobial activity against selected bacterial strains and antioxidant activity using the TAC, FRAP, NO and ABTS models. In vitro antioxidant activity of 1' showed a moderate activity, but weaker scavenging activity than the standards of ascorbic acid and trolox. Results of the antibacterial activity of the tested compound showed that it possesses a higher activity against Bacillus anthracis, Bacillus cereus, Bacillus polymyxa, Bacillus subtilis and Staphylococcus aureus than the two standard drugs, streptomycin and tetracycline, and better activity than tetracycline against Escherichia doll. (C) 2017 Elsevier B.V. All rights reserved. Central Science Laboratory, Obafemi Awolowo University, Ile-Ife; NSF-MRI programNational Science Foundation (NSF)NSF - Office of the Director (OD) [CHE-1039027] We would like to acknowledge the support of the Central Science Laboratory, Obafemi Awolowo University, Ile-Ife. JPJ acknowledges the NSF-MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.

Chalcones are natural biocides. Several publications appear every year covering the synthesis of chalcones because they exhibit an array of pharmacological activities. In this study, some condensation reactions of 1-Indanone with substituted benzaldehydes were carried out under different reaction conditions. The chalcone products were converted to their corresponding 2,4-Dinitrophenylhydrazone derivatives and evaluated against five gram-positive and eight gram-negative bacteria for their in vitro antibacterial property. Antimicrobial activity was observed against many of the tested strains, with zones of inhibition ranging from 10 to 28 mm. In many cases, the hydrazone derivatives were more active than their chalcone precursors. The best results were obtained against gram-negative bacteria for most of the compounds. Compound 1b was the most active with its minimum inhibitory concentrations (MICs) against six strains of bacteria ranging from 15.6 to 31.3 µg/ml, hence, could be developed as an antibacterial agent against infections caused by some gram-negative bacteria such as Pseudomonas aeruginosa and Salmonella typhimurium. Key words: Antibacterial activity, chalcones, 2,4-Dinitrophenylhydrazones, 1-Indanone, microwave-assisted synthesis, minimum inhibitory concentration.

This work reports the synthesis and characterization of 2,3a,8b-trihydroxy-3-(thiophen-2-ylcarbonyl)-2-(trifluoromethyl)-2,3,3a,8b-tetrahydro-4H-indeno[1,2-b]furan-4-one. The compound was characterized by elemental analysis, IR, NMR and HREIMS spectra. The solid state structure of the title compound was established by single crystal X-ray diffraction. The crystal structure adopts triclinic space group P-1 , and stabilized by intermolecular non-covalent interactions. The intermolecular hydrogen bonding interactions, C H⋯F C and O H⋯O C, connect the molecules into a layered network structure. The compound showed broad spectrum (in vitro) activity against nine strains of Gram positive and four strains of Gram negative bacteria.

Aim This study was designed to assess the antioxidant property of crude methanolic extract of Tetracera potatoria roots (MeTp); a bioactive constituent isolated from it, betulinic acid (BA) and a combination of BA with ascorbic acid. Methods The crude extract was obtained by cold extraction. Phytochemical screening of the crude extract was carried out using standard methods. Isolation of betulinic acid (BA) was effected by Accelerated Gradient Chromatography (AGC) fractionation of MeTp. Structural elucidation of the isolated BA was done with 1 H and 13 C NMR spectroscopic technique. MeTp, isolated BA and BA plus ascorbic acid mixture (1:1) were evaluated for their antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl, (DPPH) method. Results The phytochemical analysis showed the presence of alkaloids, flavonoids, cardiac glycosides, saponins and tannins. Anthraquinones were absent. The 1 H and 13 C NMR data obtained for the isolated BA were in accordance with published data. Antioxidant activity (IC 50 ) of tested materials ranged from 18 to 148 μg/ml, with MeTp having the highest value relative to ascorbic acid, the reference standard. The radical scavenging activities of MeTp and that of BA plus ascorbic acid mixture were greater than that of ascorbic acid alone, indicating synergism between ascorbic acid and betulinic acid. Conclusion The findings established the antioxidant property of methanolic root extract of T . potatoria . The combination of betulinic acid and ascorbic acid could be useful for the development of new antioxidant drug.

Background/aim Quinazolinone derivatives are well-known for their diverse pharmacological activities. For example, methaqualone is used as a sedative-hypnotic drug. One common method of synthesizing quinazolinones utilizes the condensation of anthranilamide with structurally diverse carbonyl compounds. In this present study, the aim is to carry out some condensation reactions of anthranilamide under microwave irradiation, characterizing the products and evaluating their antibacterial property. Methods The antibacterial activity of the microwave-assisted condensation products of anthranilamide with phthalic anhydride, succinic anhydride, N-acetylisatin and oxalic acid were evaluated in-vitro against twenty-four pathogenic bacterial strains, using the agar-well diffusion method. Results The synthesized compounds exhibited broad spectrum antibacterial activity with zones of inhibition ranging from 10 to 30 mm. The benzodiazepine compound 7 showed the highest activity, out of the synthesized compounds, with lower inhibitory concentrations than the reference antibiotics used in twelve cases. Conclusion The results of the antibacterial screening of the synthesized quinazolinone derivatives showed that they possess broad spectrum activity at concentrations comparable with those of the reference antibiotics and in several cases some of the compounds were active at lower concentrations.

3-Hydrazinoquinoxalin-2(1H)-one was prepared from quinoxaline-2,3-dione and subsequently used for the synthesis of some potentially biologically active 3-(pyrazol-1-yl)quinoxalin-2(1H)-one derivatives. While 3-(3,5-dimethylpyrazol-1-yl)quinoxalin-2(1H)-one showed a comparative effect with streptomycin, 3-(5-oxo-3-phenyl-4,5-di- hydropyrazol-1-yl)quinoxalin-2(1H)-one was found to be the most active with an MIC value of 7.8 μg/ml.

Schiff bases derived from isatin have recently received great attention due to their wide applications as synthetic precursors and biologically potent compounds. Metal complexes of Co(II), Cu(II), Fe(III), Mn(II), and Ni(II) were synthesized by conventional refluxing with the Schiff base derived from isatin and sulfanilamide in the ratio 1:1 in the presence of concentrated ammonia solution. The characterizations of these compounds have been done using 1HNMR, 13CNMR, electronic spectra, room temperature magnetic susceptibility, elemental analysis, and molecular weight determinations. The ligand acts in a bidentate manner in the four-coordinate tetrahedral Mn(II) complex, coordinating through the azomethine N and enol O atoms and also in the Ni(II) complex, which possesses a second molecule of the ligand coordinating via the keto O and the azomethine N atoms. The ligand acts in a tridentate manner in the tetrahedral Co(II) and Fe(III) complexes, where an oxygen atom of the sulfonamido group is also coordina...

Isatin reacts with thiosemicarbazide in 50% aqueous alcohol under reflux to give isatin-3-thiosemicarbazone (1′). Compound 1′ cyclizes on treatment with acetic anhydride and pyridine to yield 1,3′-diacetyl-5′-acetamido-3(1H)-spiro[indole-3,2′-[1,3,4]-thiadiazol]-2(1H)-one, 2′. Subsequent reaction of the diacetyl spiro compound, 2′, with hydrazine hydrate at room temperature furnished a white product, which was characterized by spectroscopic means to be 1,3′-diacetyl-5′-amino-3(1H)-spiro[indole-3,2′-[1,3,4]-thiadiazol]-2(1H)-one, 3′. All three compounds (1′, 2′, 3′) were tested for antibacterial activity against six Gram-positive and four Gram-negative bacteria. 1′ showed activity against five Gram-positive and one Gram-negative bacterial strains, while 2′ showed activity against three Gram-positive and two Gram-negative bacterial strains. Compound 3′ showed activity against four Gram-positive and three Gram-negative bacterial strains (better activity than streptomycin, the reference standard).

The synthesis of some quinoxalinesulfonyl derivatives is described. Two of the synthesized derivatives, 2-oxo-1,2-dihydroquinoxaline-6-sulfonyl azide (3a) and 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl azide (3b), were screened in vitro for their growth inhibitory activity against nine strains of Gram-positive and seven strains of Gram-negative bacteria, along with two fungal isolates. The two compounds showed broad spectrum (in vitro) activity against the bacterial strains.

A new synthetic route to (trisubstitutedphosphoranylidene)sulfamides via the reaction of sulfamoyl azide with trisubstituted phosphines is described.

The oxidation reactions of a series of quinoxaline derivatives, using KMnO4 in the presence or absence of NaOH, are described. Neutral oxidation of 2-chloro- and 2, 3-dichloroquinoxalines 2–4 afforded the corresponding chloro- and dichloropyrazinedicarboxylic acids 13 and 14 in good yield. On the other hand, oxidation of quinoxalin-2(1H)-one and 1, 4-dihydroquinoxaline-2, 3-dione derivatives in alkaline medium gave different products, with the quinoxalin-2(1H)-one (5) forming 1, 4-dihydroquinoxaline-2, 3-dione (9), while various substituted quinoxalin-2, 3-dione derivatives (see 9–11) gave a new type of dimeric products. The structural assignments for the new compounds were based on spectroscopic data.

Some aromatic sulfonyl azides have been reduced, in various solvents, with sodium borohydride, in the presence or absence of Te element to the corresponding sulfonamides. Other functionals groups like the imino group may also be reduced.

Imidazolium and 2-methylimidazolium chlorochromates (C3H5N2 +ClCrO3 − and C4H7N2 +ClCrO3 −, respectively) have been synthesized and characterized by elemental analysis, infra red and 13C nmr spectra. The compounds oxidize primary and secondary alcohols to their respective carbonyl compounds while ketoximes and aldoximes are deoximated to the corresponding ketones and aldehydes at room temperature.

The oxidation reactions of a series of quinoxaline derivatives, using KMnO4 in the presence or absence of NaOH, are described. Neutral oxidation of 2-chloro- and 2, 3-dichloroquinoxalines 2–4 afforded the corresponding chloro- and dichloropyrazinedicarboxylic acids 13 and 14 in good yield. On the other hand, oxidation of quinoxalin-2(1H)-one and 1, 4-dihydroquinoxaline-2, 3-dione derivatives in alkaline medium gave different products, with the quinoxalin-2(1H)-one (5) forming 1, 4-dihydroquinoxaline-2, 3-dione (9), while various substituted quinoxalin-2, 3-dione derivatives (see 9–11) gave a new type of dimeric products. The structural assignments for the new compounds were based on spectroscopic data.

A variety of the title pyrazolylquinoxalinone derivatives are synthesized by condensation reactions of hydrazinoquinoxalinone (IV) with β-diketones, β-keto esters of cyanoacetate.

A simple and efficient method has been developed for the synthesis of various 2-quinoxalinone-3-hydrazone derivatives using microwave irradiation technique. The series of 2-quinoxalinone-3-hydrazone derivatives synthesized, were structurally confirmed by analytical and spectral data and evaluated for their antimicrobial activities. The results showed that this skeletal framework exhibited marked potency as antimicrobial agents. The most active antibacterial agent was 3-{2-[1-(6-chloro-2-oxo-2H-chromen-3-yl)ethylidene]hydrazinyl}quinoxalin-2(1H)-one, 7 while 3-[2-(propan-2-ylidene)hydrazinyl]quinoxalin-2(1H)-one, 2 appeared to be the most active antifungal agent.

Some aromatic sulfonyl azides have been reduced, in various solvents, with sodium borohydride, in the presence or absence of Te element to the corresponding sulfonamides. Other functionals groups like the imino group may also be reduced.

Imidazolium and 2-methylimidazolium chlorochromates (C3H5N2 +ClCrO3 − and C4H7N2 +ClCrO3 −, respectively) have been synthesized and characterized by elemental analysis, infra red and 13C nmr spectra. The compounds oxidize primary and secondary alcohols to their respective carbonyl compounds while ketoximes and aldoximes are deoximated to the corresponding ketones and aldehydes at room temperature.

New pyrido- and pyrimidino[2\',1\':2,3][1,3] thiazolo[4,5-b] quinoxalin-12-ium salts 7 could be synthesized from cyclizations of 2,3-dichloroquinoxalines with 2-mercaptopyridine and 2-mercaptopyrimidine, respectively. The pyrimidino- thiazoloquinoxaline 7d reacts further with acetyl-compounds to afford the corresponding 1-(acylmethyl)-1H-pyrimidino[2\',1\':2,3][1,3] thiazolo[4,5-b]quinoxalines, 9 . Ife Journal of Science Vol.6(1) 2004: 23-29

2,3-Dichloroquinoxaline and some of its derivatives have been reacted with malononitrile and ethyl cyanoacetate to yield a variety of 3-chloro-2-(cyanomethylene)- 1,2-dihydroquinoxaline derivatives. The reaction of 3-chloro-2-(dicyanomethylene)-1,2- dihydroquinoxaline (2e) with pyridine and its methyl derivatives led to the zwitterionic structures 6a-6c. The structures of the newly synthesized compounds were assigned by spectroscopic data and elemental analyses.

In the title compound, C22H24N2O2·H2O, the co-crystallized water molecule interacts with the N and O atoms of the molecule through Ow—H...N, Ow—H...O(methyl) and N—H...Ow hydrogen-bonding interactions. These hydrogen bonds, along with the intermolecular N—H...O=C hydrogen-bonding interactions, connect the molecules into a three-dimensional network. The dihedral angle between the two aromatic rings is 65.46 (10)°.

A number of triarylvinyl halides and acetates were reduced with lithium aluminium hydride using various transition metal chlorides as catalysts. The vinylic halides were reduced to the corresponding alkenes while the vinylic acetates were reduced to mixtures of triarylketones and alcohols. The reduction of labeled vinylic halides did not result in any scrambling of the label from C-2 to C-1. The reactions took place under mild conditions and relatively fast reaction times. Keywords: triarylvinyl chlorides, triarylvinyl acetates, lithium aluminium hydride reduction, 1,2,2-triarylethanol, 1,1,2-tri-p-tolyl[1-13C]ethane.

A mixture of 2,3-dichloroquinoxaline 1[1] (5.0 g, 25 mmol) and diethanolamine 2 (12 mL, 125 mmol) was heated to 130° C for 3 h, with magnetic stirring.[...]

Acetolyses of a 15 mM solution of a doubly labeled trianisylvinyl substrate, 1,2-dianisyl-2-p-[14C]methoxyphenyl[2-13C]vinyl bromide (1-Br-2-13C-2-methoxy-14C), were carried out in the presence of different amounts of added NaOAc (30–450 mM) or NaOAc (30 or 300 mM) and Et4NBr (75–1000 mM). Isotopic scramblings of the 13C or 14C label from C-2 to C-1 were observed in both the reaction product and the recovered unconsumed reactant, indicating the occurrence of cycles of ionization, 1,2-anisyl shift, and return. The extent of scrambling was found to decrease with increasing concentrations of NaOAc, and a further decrease in scrambling was noted with the additional presence of Et4NBr. These findings are attributable to a competition between the 1,2-shift process and capture of the cation by the added nucleophiles.Analysis of the experimental data suggests that the nucleophilic species chiefly involved in the product-forming capture reaction is the acetate ion rather than HOAc or the Na+OAc− ion-pair. Comparisons of the scrambling data, expressed as "% rearrangement", with the assumption that 100% rearrangement corresponds to 33.3% and 50.0% scramblings of the 14C ring label and the 13C chain label, respectively, led to the conclusion that complete equilibration of the labels is achieved in that portion of the molecules that have undergone rearrangement only when the acetolyses are carried out in the presence of high concentrations of added salts. Mechanistic implications of these observations are discussed.