Relevant bibliographies by topics / Heterocyclic compounds. Stereochemistry / Journal articles
To see the other types of publications on this topic, follow the link: Heterocyclic compounds. Stereochemistry.

Journal articles on the topic 'Heterocyclic compounds. Stereochemistry'

Author: Grafiati
Published: 4 June 2021
Last updated: 30 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 41 journal articles for your research on the topic 'Heterocyclic compounds. Stereochemistry.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Perlmutter, Patrick. "The Nucleophilic Addition/Eiectrophilic Ring Closure Route to Bio-Active Heterocycles." Current Medicinal Chemistry 3, no. 2 (April 1996): 139–52. http://dx.doi.org/10.2174/092986730302220302101738.

Full text
Abstract:
Abstract: Many bio-active compounds contain one or more saturated or partially saturated heterocycles. Most of these contain one or more stereo­ centres. As a result any attempts to synthesize these compounds must take full account of the stereochemistry. In this article a new approach to the stereoselective synthesis of heterocycles is reviewed. The emphasis is on oxygen-containing heterocycles. The approach involves a sequence of a nucleophilic addition reaction followed by an electrophilic ring closure. Examples are given of the stereoselective synthesis of the heterocyclic subunits of macrolide and polyether antibiotics, y­butyrolactone autoregulators, marine polyether toxins and C-glycosides.
APA, Harvard, Vancouver, ISO, and other styles
2

El-Sonbati, A. Z., A. A. M. Belal, S. I. El-Wakeel, and M. A. Hussien. "Stereochemistry of new nitrogen containing heterocyclic compounds." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 60, no. 4 (March 2004): 965–72. http://dx.doi.org/10.1016/s1386-1425(03)00326-3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Azzena, Ugo, Massimo Carraro, and Luisa Pisano. "Addressing Stereochemistry of Heterocyclic Compounds by DFT NMR Calculations." Chemistry of Heterocyclic Compounds 54, no. 4 (April 2018): 380–88. http://dx.doi.org/10.1007/s10593-018-2279-x.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Larina, Lyudmila I. "The Structure of Biologically Active Functionalized Azoles: NMR Spectroscopy and Quantum Chemistry." Magnetochemistry 8, no. 5 (May 6, 2022): 52. http://dx.doi.org/10.3390/magnetochemistry8050052.

Full text
Abstract:
This review summarizes the data on the stereochemical structure of functionalized azoles (pyrazoles, imidazoles, triazoles, thiazoles, and benzazoles) and related compounds obtained by multipulse and multinuclear 1H, 13C, 15N NMR spectroscopy and quantum chemistry. The stereochemistry of functionalized azoles is a challenging topic of theoretical research, as the correct interpretation of their chemical behavior and biological activity depends on understanding the factors that determine the stereochemical features and relative stability of their tautomers. NMR spectroscopy, in combination with quantum chemical calculations, is the most convenient and reliable approach to the evaluation of the stereochemical behavior of, in particular, nitrogen-containing heteroaromatic and heterocyclic compounds. Over the last decade, 15N NMR spectroscopy has become almost an express method for the determination of the structure of nitrogen-containing heterocycles.
APA, Harvard, Vancouver, ISO, and other styles
5

Askri, Sonia, Amal Dbeibia, Chadlia Mchiri, Sarra Boudriga, Michael Knorr, Emmanuel Roulland, Olivier Laprévote, Nathalie Saffon-Merceron, and Rafik Gharbi. "Antimicrobial Activity and In Silico Molecular Docking Studies of Pentacyclic Spiro[oxindole-2,3′-pyrrolidines] Tethered with Succinimide Scaffolds." Applied Sciences 12, no. 1 (December 30, 2021): 360. http://dx.doi.org/10.3390/app12010360.

Full text
Abstract:
Three-component cascade reactions of (E)-3-arylidene-1-methyl-pyrrolidine-2,5-diones, L-valine and various isatin derivatives are described. A series of 17 spiropyrrolidine derivatives with wide structural complexity and diversity have been thus obtained in moderate to excellent yields under mild reaction conditions. The structure and stereochemistry of these N-heterocyclic cycloadducts has been established by spectroscopic techniques and unambiguously confirmed by a single-crystal X-ray diffraction analysis performed on one derivative. UV-visible spectra have been recorded for all new compounds. Furthermore, the synthesized N-heterocyclic compounds have been screened for their in vitro antibacterial and antifungal activities. Several derivatives exhibited moderate to good activities, comparable to those of the known standard drugs Amphotericin B and Tetracycline. Structural activity relationships (SARs) and molecular docking of the most promising derivatives into the binding sites of glucosamine 6-phosphate synthase (GlcN6P) and methionyl-trna-synthetase (1PFV) were also established. Furthermore, pharmacokinetic studies indicate that the heterocycles exhibit acceptable predictive ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties and good drug ability.
APA, Harvard, Vancouver, ISO, and other styles
6

Boudriga, Sarra, Saoussen Haddad, Vikneswaran Murugaiyah, Moheddine Askri, Michael Knorr, Carsten Strohmann, and Christopher Golz. "Three-Component Access to Functionalized Spiropyrrolidine Heterocyclic Scaffolds and Their Cholinesterase Inhibitory Activity." Molecules 25, no. 8 (April 23, 2020): 1963. http://dx.doi.org/10.3390/molecules25081963.

Full text
Abstract:
A novel one-pot [3+2]-cycloaddition reaction of (E)-3-arylidene-1-phenyl-succinimides, cyclic 1,2-diketones (isatin, 5-chloro-isatin and acenaphtenequinone), and diverse α-aminoacids such as 2-phenylglycine or sarcosine is reported. The reaction provides succinimide-substituted dispiropyrrolidine derivatives with high regio- and diastereoselectivities under mild reaction conditions. The stereochemistry of these N-heterocycles has been confirmed by four X-ray diffraction studies. Several synthetized compounds show higher inhibition on acetylcholinesterase (AChE) than butyrylcholinesterase (BChE). Of the 17 synthesized compounds tested, five exhibit good AChE inhibition with IC50 of 11.42 to 22.21 µM. A molecular docking study has also been undertaken for compound 4n possessing the most potent AChE inhibitory activity, disclosing its binding to the peripheral anionic site of AChE enzymes.
APA, Harvard, Vancouver, ISO, and other styles
7

Antus, Sándor, Katalin Gulácsi, László Juhász, Loránd Kiss, and Tibor Kurtán. "Synthesis of naturally occurring o-heterocyclic compounds of biological activity." Pure and Applied Chemistry 76, no. 5 (January 1, 2004): 1025–32. http://dx.doi.org/10.1351/pac200476051025.

Full text
Abstract:
The total synthesis of (−)-cabenegrin A-I was achieved via (−)-6aR,11aR maackiain, which was obtained by optical resolution of racemic maackiain using S-(−)-alpha-methylbenzyl isocyanate. The synthesis of rac-maackiain was performed both with the Heck oxyarylation of 7-benzyloxy-2H-chromene and the BF3OEt2 mediated ring closure of isoflavan-4-ol derivatives, the latter of which provided much higher yields. The first enantioselective synthesis of trans-6aS,11aR-pterocarpan and its conversion to cis-6aS,11aS -ptarocarpan was also presented starting from racemic 2'-benzyloxyflavanone. Their stereochemistry was deduced by circular dichroism (CD) as well as by X-ray analysis of the ketal intermediate.
APA, Harvard, Vancouver, ISO, and other styles
8

Constable, Edwin C., Richard M. Hartshorn, and Catherine E. Housecroft. "1,1′-Biisoquinolines—Neglected Ligands in the Heterocyclic Diimine Family That Provoke Stereochemical Reflections." Molecules 26, no. 6 (March 13, 2021): 1584. http://dx.doi.org/10.3390/molecules26061584.

Full text
Abstract:
1,1′-Biisoquinolines are a class of bidentate nitrogen donor ligands in the heterocyclic diimine family. This review briefly discusses their properties and the key synthetic pathways available and then concentrates upon their coordination behaviour. The ligands are of interest as they exhibit the phenomenon of atropisomerism (hindered rotation about the C1–C1′ bond). A notation for depicting the stereochemistry in coordination compounds containing multiple stereogenic centers is developed. The consequences of the chirality within the ligand on the coordination behaviour is discussed in detail.
APA, Harvard, Vancouver, ISO, and other styles
9

Simoni, Daniele, Riccardo Rondanin, Riccardo Baruchello, Marinella Roberti, Marcello Rossi, Stefania Grimaudo, Natale D'Alessandro, Francesco Paolo Invidiata, and Manlio Tolomeo. "Retinoic acid and analogs as potent inducers of differentiation and apoptosis. New promising chemopreventive and chemotherapeutic agents in oncology." Pure and Applied Chemistry 73, no. 9 (September 1, 2001): 1437–44. http://dx.doi.org/10.1351/pac200173091437.

Full text
Abstract:
In this report we will describe the preparation and the biological activity of a novel class of heterocyclic arotinoids endowed with potent cytotoxic and apoptotic acitivity. Structure­activity relationship studies revealed that the different stereochemistry at the C9 double bond of retinoids seems associated with a different biological activity: potent apoptotic activity for the cis-isomers, whereas differentiating activity for the trans structures. An interesting modified Wittig procedure that allows easily to arotinoids will also be described. The substitution of the alkenyl portion with a more flexible oxymethyl or aminomethyl moiety gave compounds with poor activity, whereas isoxazole-bridged arotinoids allowed compounds active also on multidrug-resistant (MDR) leukemia cell lines.
APA, Harvard, Vancouver, ISO, and other styles
10

HIRTOPEANU, Anca, Cristina FLOREA, and Michaela Dina STANESCU. "Stereochemistry – key role in the rearrangements of dibenzo-C8 and -C9 derivatives." Revue Roumaine de Chimie 66, no. 2 (2021): 105–17. http://dx.doi.org/10.33224/rrch.2021.66.2.01.

Full text
Abstract:
This paper presents the pioneer research being initiated and conducted by the late Acad. C. D. Nenitzescu and Acad. E. Cioranescu in the Department of Organic Chemistry of the University POLITEHNICA Bucharest, and the Center of Organic Chemistry of the Romanian Academy,. A review of these works seems necessary in order to emphasize the importance of the described researches in their theoretical and practical aspects. The dibenzo-cycloalkanes are compounds with interesting behavior, giving different rearranged products, difficult to obtain by other type of syntheses. The modification of the product stability given by adding a carbon atom is also of interest, the steric factor changing radically the behavior of homologue compounds. The potential biological activity of some of these compounds is important for practical applications. The studied compounds were the subject of several PhD theses of the members of Acad. Cioranescu’s research team. It should also be mentioned that the obtained bridged compounds are raw materials for interesting heterocyclic compounds like the tryptycene analogue prepared in collaboration with Acad. A. T. Balaban.
APA, Harvard, Vancouver, ISO, and other styles
11

El-bindary, Ashraf A., and Adel Z. El-sonbati. "Stereochemistry of New Nitrogen Containing Heterocyclic Aldehydes. II. Novel Bis-Bidentate Azodye Compounds." Spectroscopy Letters 32, no. 4 (July 1999): 581–600. http://dx.doi.org/10.1080/00387019909350008.

Full text
APA, Harvard, Vancouver, ISO, and other styles
12

Nurkenov, O. A., S. D. Fazylov, G. K. Mukusheva, Ye V. Minayeva, I. V. Kulakov, Zh S. Nurmaganbetov, A. S. Kishkentaeva, and A. R. Zhasymbekova. "HYBRID MOLECULES BASED ON ALKALOIDS." Chemical Journal of Kazakhstan 3 (September 30, 2021): 67–82. http://dx.doi.org/10.51580/2021-1/2710-1185.40.

Full text
Abstract:
This review has been summarized the data on the synthesis of new hybrid derivatives based on alkaloid molecules. At the same time, there have been analyzed methods for obtaining hybrid structures containing fragments of natural compounds molecules in combination with other biologically active plant metabolites, as leading compounds for the development of new pharmacologically valuable agents, with the aim of creating new original drugs. The combination of pharmacophoric residues in one molecule, namely various aromatic and heterocyclic substituents in the nucleoside position of natural alkaloids, opens up new possibilities for both the subsequent chemical modification of the polyfunctional derivatives obtained and their new diverse biological activity. Effective methods of synthesis have been developed on the basis of directed transformations of these compounds (or their precursors). A wide range of pharmaco-logical properties of combined compounds of these series with a combination of low toxicity is promising. Considering that the preparation of combined derivatives based on alkaloid molecules has been insufficiently studied, the targeted synthesis of new com-pounds is of interest both in terms of new medicinespreparation and the development of new methods of organic synthesis, as well as the molecules stereochemistry determination of a new series of compounds.
APA, Harvard, Vancouver, ISO, and other styles
13

Liu, Hui, and B. Mario Pinto. "Design and synthesis of selenonium and sulfonium ions related to the naturally occurring glucosidase inhibitor salacinol." Canadian Journal of Chemistry 84, no. 10 (October 1, 2006): 1351–62. http://dx.doi.org/10.1139/v06-100.

Full text
Abstract:
Four series of analogues of the naturally occurring glucosidase inhibitor salacinol were synthesized for structure–activity studies with different glycosidase enzymes. The target zwitterionic compounds were synthesized by means of nucleophilic attack at the least-hindered carbon atom of the 1,3-cyclic sulfates derived from D-glucose and D-mannose by the isopropylidene-protected 1,4-anhydro-4-thio- and seleno-D-allitols and the 4-thio- and seleno-L-allitols. Deprotection of the coupled products afforded the novel sulfonium and selenonium ions containing polyhy droxylated acyclic chains of four and six carbons, with different stereochemistry at the stereogenic centers and with 1,4-anhydro-4-seleno or 4-thio-D- or L- alditol heterocyclic rings. The compounds showed no significant activity against recombinant human maltase glucoamylase (MGA), a critical intestinal glucosidase involved in the processing of oligosaccharides of glucose into glucose itself.Key words: glycosidase inhibitors, zwitterionic, selenonium salts, sulfonium salts, cyclic sulfates, L-ascorbic acid, D-gulonic-γ-lactone.
APA, Harvard, Vancouver, ISO, and other styles
14

Demir-Ordu, Öznur, Esra Müjde Yılmaz, and İlknur Doğan. "Determination of the absolute stereochemistry and the activation barriers of thermally interconvertible heterocyclic compounds bearing a naphthyl substituent." Tetrahedron: Asymmetry 16, no. 22 (November 2005): 3752–61. http://dx.doi.org/10.1016/j.tetasy.2005.09.019.

Full text
APA, Harvard, Vancouver, ISO, and other styles
15

Saudale, Fredy Z., and Irenes R. S. Suatu. "Pemodelan Homologi Komparatif FABP Belalang Kembara (Locusta migratoria) Dengan PHYRE2 dan Skrining Virtual Inhibitor Potensial." Indo. J. Chem. Res. 7, no. 2 (January 31, 2020): 127–40. http://dx.doi.org/10.30598//ijcr.2020.7-fre.

Full text
Abstract:
The outbreak of locusta migratoria has caused a local crisis in production and cultivation of agricultural crops in East Nusa Tenggara Province. FABP (Fatty Acid-Binding Protein) plays an important role in transporting fatty acids from cytoplasm into mitochondria to generate ATP energy for locusta to fly and migrate. FABP inhibition is an attractive strategy to be exploited for novel insecticide development. Comparative homology modeling using Phyre2 had been used to generate two FABP models built from desert locusta (Schistocerca gregaria, 98% percent identity) and mice (Mus musculus, 40% percent identity) FABP protein as templates. Both FABP models showed an acceptable quality of stereochemistry and structural energy with lower atomic clash scores after refinement. Virtual screening identified potent inhibitor candidates with highest affinity energies which are (i) a heterocyclic compound C00628966 (-10.2 kcal/mol) and (iii) an imidazole derivative C15721579 (-8.5 kcal/mol) that were stabilized through a hydrogen bond with Ser53 also (iii) a pyrimidine derivative C73698912 (-8.1 kcal/mol) stabilized through hydrogen bonds with Thr57, Thr62 and Ser55. Their interactions resemble inhibitors that have been known to inhibit homologous FABP in humans. Therefore, these compounds warrant further in vitro validation and assay for development of selective insecticides to control locusta population.
APA, Harvard, Vancouver, ISO, and other styles
16

Darabantu, Mircea, Gerard Ple, Sorin Mager, Camelia Puscas, and Eleonora Cotora. "Synthesis and stereochemistry of some heterocyclic saturated compounds based on l-p-nitrophenylserinol skeleton (III). 1,3-Dioxanic Schiff bases." Tetrahedron 53, no. 5 (February 1997): 1909–22. http://dx.doi.org/10.1016/s0040-4020(96)01106-4.

Full text
APA, Harvard, Vancouver, ISO, and other styles
17

Kuznetsov, Valerij. "Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems." Molecules 25, no. 10 (May 23, 2020): 2437. http://dx.doi.org/10.3390/molecules25102437.

Full text
Abstract:
Over the past three decades, carbon nanotubes and fullerenes have become remarkable objects for starting the implementation of new models and technologies in different branches of science. To a great extent, this is defined by the unique electronic and spatial properties of nanocavities due to the ramified π-electron systems. This provides an opportunity for the formation of endohedral complexes containing non-covalently bonded atoms or molecules inside fullerenes and nanotubes. The guest species are exposed to the force field of the nanocavity, which can be described as a combination of electronic and steric requirements. Its action significantly changes conformational properties of even relatively simple molecules, including ethane and its analogs, as well as compounds with C−O, C−S, B−B, B−O, B−N, N−N, Al−Al, Si−Si and Ge−Ge bonds. Besides that, the cavity of the host molecule dramatically alters the stereochemical characteristics of cyclic and heterocyclic systems, affects the energy of pyramidal nitrogen inversion in amines, changes the relative stability of cis and trans isomers and, in the case of chiral nanotubes, strongly influences the properties of R- and S-enantiomers. The present review aims at primary compilation of such unusual stereochemical effects and initial evaluation of the nature of the force field inside nanotubes and fullerenes.
APA, Harvard, Vancouver, ISO, and other styles
18

Darabantu, Mircea, Gerard Plè, Sorin Mager, Luiza Gaina, Eleonora Cotora, Adrian Mates, and Loredana Costas. "Synthesis and stereochemistry of some heterocyclic saturated compounds based on l-p-Nitrophenylserinol skeleton (II). 1-Aza-3,7-dioxabicyclo[3.3.0]octanes." Tetrahedron 53, no. 5 (February 1997): 1891–908. http://dx.doi.org/10.1016/s0040-4020(96)01105-2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
19

DARABANTU, M., G. PLE, S. MAGER, C. PUSCAS, and E. COTORA. "ChemInform Abstract: Synthesis and Stereochemistry of Some Heterocyclic Saturated Compounds Based on l-p-Nitrophenylserinol Skeleton. Part 3. 1,3-Dioxanic Schiff Bases." ChemInform 28, no. 21 (August 4, 2010): no. http://dx.doi.org/10.1002/chin.199721082.

Full text
APA, Harvard, Vancouver, ISO, and other styles
20

DARABANTU, M., G. PLE, S. MAGER, L. GAINA, E. COTORA, A. MATES, and L. COSTAS. "ChemInform Abstract: Synthesis and Stereochemistry of Some Heterocyclic Saturated Compounds Based on l-p-Nitrophenylserinol Skeleton. Part 2. 1-Aza-3,7- dioxabicyclo(3.3.0)octanes." ChemInform 28, no. 21 (August 4, 2010): no. http://dx.doi.org/10.1002/chin.199721081.

Full text
APA, Harvard, Vancouver, ISO, and other styles
21

Darabantu, Mircea, Gerard Ple, Sorin Mager, Eleonora Cotora, Luiza Gaina, Loredana Costas, and Adrian Mates. "Synthesis and stereochemistry of some heterocyclic saturated compounds based on l-p-nitrophenylserinol skeleton (I). Ring-chain tautomerism of some schiff bases of l-p-nitrophenylserinol." Tetrahedron 53, no. 5 (February 1997): 1873–90. http://dx.doi.org/10.1016/s0040-4020(96)01104-0.

Full text
APA, Harvard, Vancouver, ISO, and other styles
22

DARABANTU, M., G. PLE, S. MAGER, E. COTORA, L. GAINA, L. COSTAS, and A. MATES. "ChemInform Abstract: Synthesis and Stereochemistry of Some Heterocyclic Saturated Compounds Based on l-p-Nitrophenylserinol Skeleton. Part 1. Ring-Chain Tautomerism of Some Schiff Bases on l-p-Nitrophenylserinol." ChemInform 28, no. 21 (August 4, 2010): no. http://dx.doi.org/10.1002/chin.199721080.

Full text
APA, Harvard, Vancouver, ISO, and other styles
23

Black, DS, GB Deacon, GL Edwards, and BM Gatehouse. "Organomercury Compounds. XXXI. Preparations and 199Hg N.M.R. Spectra of Organomercury Derivatives of 2-Phenylpyridine, Benzo[h]quinoline, 1-Phenylpyrazole and 3,4,5-Trimethyl-1-phenylpyrazole, and the X-Ray Crystal Structure of Bis[2-(pyridin-2'-yl)phenyl]mercury." Australian Journal of Chemistry 46, no. 9 (1993): 1323. http://dx.doi.org/10.1071/ch9931323.

Full text
Abstract:
2-(Pyridin-2'-yl) phenylmercuric acetate has been prepared by mercuration of 2-phenylpyridine. Symmetrization of the corresponding chloride by alkaline sodium stannite gave bis [2-(pyridin-2'-yl)phenyl]mercury, which was also prepared from 2-(2'-aminophenyl)pyridine by the diazo method and treatment of the initial product with copper powder and aqueous ammonia. Mercuration of benzo [h] quinoline and 3,4,5-trimethyl-1-phenylpyrazole with mercuric acetate followed by treatment with lithium chloride yielded benzo [h]quinolin-10-ylmercuric chloride and 2-(3',4',5'-trimethylpyrazol-1'-yl) phenylmercuric chloride respectively. Treatment of the former product with tribromide ions gave 10-bromobenzo[h] quinoline. The exchange Grignard reaction between 1-phenylpyrazole and ethylmagnesium bromide to give 2-(pyrazol-1'-yl) phenylmagnesium bromide has been monitored by reactions with benzonitrile and D2O to establish optimum conditions for reaction with mercuric bromide giving bis [2-(pyrazol-1'-yl)phenyl]mercury. The 199Hg n.m.r. chemical shifts of the majority of mercurials are shifted substantially downfield relative to the corresponding simple phenylmercurials consistent with weak intramolecular coordination by the heterocyclic nitrogen donor atoms, but a small upfield shift is observed for bis [2-(pyrazol-1'-yl)phenyl]mercury. The X-ray crystal structure of bis [2-(pyridin-2′-yl)phenyl]mercury [monoclinic, space group P21/n, a 12.746(2), b 11.660(2), c 5.698(1) Ǻ, β 92.81(1)′, V 845.8 Ǻ3] shows a centrosymmetric molecule with strong linear two coordination [Hg-C 2.098(8) Ǻ; C-Hg-C 180.0°] and significant but much weaker Hg-N interactions [Hg-N 2.798(7) Ǻ; N-Hg-N 180.0°] giving overall distorted square planar stereochemistry. The phenyl rings are mutually coplanar, whilst the two pyridin-2'-yl rings are parallel and inclined at 10.8° to the phenyl groups.
APA, Harvard, Vancouver, ISO, and other styles
24

SADEKOV, I. D., B. B. RIVKIN, A. V. ZAKHAROV, and V. I. MINKIN. "ChemInform Abstract: Synthesis and Structure of Aromatic and Heterocyclic Tellurium Compounds. Part 33. Synthesis of (2-(Aryltelluro)vinyl)aldehydes and - ketones and Stereochemistry of Nucleophilic Substitution at the Vinylic Carbon Atom." ChemInform 28, no. 18 (August 4, 2010): no. http://dx.doi.org/10.1002/chin.199718213.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Yegorova, T., B. Barnych, and Z. Voitenko. "REACTION OF PYRIDO[2,1-a]ISOINDOLE WITH З (R)- AND (S)- N-α-METHILBENZYLMALEIMIDE." Bulletin of Taras Shevchenko National University of Kyiv. Chemistry, no. 1 (57) (2020): 44–47. http://dx.doi.org/10.17721/1728-2209.2020.1(57).11.

Full text
Abstract:
Selective chemical reactions create new possibilities for controlled synthesis of compounds with pre-designed properties for further use in medical chemistry, material science and other fields. This is especially useful for such synthetic methodology as [4+2] cycloaddition. Current work is dedicated to study of reactions between N-chiral maleinimides with cyclic dienes based on the pyridoisoindol. Pyrido[2,1-a]isoindol turned out to be the most practical object to study the first example of asymmetric variant of the Diels-Alder reaction involving condensed isoindols. Previously, we established that this heterocyclic system, in contrast to other azino- and azoloisoindols, upon undergoing cycloaddition with non-chiral maleinimides gives only rearranged adducts of the first type. This type of compounds have also interesting stereochemistry: in solid state they have twisted double bond (twist angle 7-10°), while in solution they exist as a mixture of athropodiastereomeres due to the asymmetric Carbon atom and hindered rotation around С–С bond between exocyclic double bond and 2-(α-pyridil)phenyl fragment. Initial expectation was that chiral induction would influence the ratio of corresponding athropodiastereomeres. Calculations show that there are four possible athropodiastereomeres due to the chiral center and sterically hindered chiral axis. In case of non-chiral dienophiles, reaction results in two major diastereomeres (for our purposes marked as A and B) with 70:30 ration and two minor isomers (marked С and D respectively), the latter constituting less than 5% of the total amount. Major and minor isomers are in constant complex equilibrium, controlled via slow rotation of around corresponding С-С bond on one hand (which is the reason for athropodiastereomeres between major forms A and B, shown via NMR spectra at different temperatures), and on the other hand – fast equilibrium due to the 1,5-sigmatropic shift (cause for the minor forms C and D). Target reaction was studied under standard conditions for this rearrangement and under the kinetic control in the inert atmosphere at -80°С using TiCl4 as catalyzer. We therefore show that reaction pathway is similar to our previous examples and results in rearranged adducts of the first type. Ratio of athropodiastereomeres (both major and minor forms) is different from previous examples using non-chiral 2-substituted maleimides. Asymmetric induction spontaneously transfers from influencing the Diels-Alder reaction to influencing synchronic sigmatropic rearrangement, which is the final stage in the formation of the rearranged adduct of the first type in condensed isoindol systems.
APA, Harvard, Vancouver, ISO, and other styles
26

Rostas, Arpad Mihai, Mihaela Badea, Lavinia L. Ruta, Ileana C. Farcasanu, Catalin Maxim, Mariana Carmen Chifiriuc, Marcela Popa, et al. "Copper(II) Complexes with Mixed Heterocycle Ligands as Promising Antibacterial and Antitumor Species." Molecules 25, no. 17 (August 19, 2020): 3777. http://dx.doi.org/10.3390/molecules25173777.

Full text
Abstract:
Complexes with mixed ligands [Cu(N-N)2(pmtp)](ClO4)2 ((1) N-N: 2,2′-bipyridine; (2) L: 1,10-phenanthroline and pmpt: 5-phenyl-7-methyl-1,2,4-triazolo[1,5-a]pyrimidine) were synthesized and structurally and biologically characterized. Compound (1) crystallizes into space group Pa and (2) in P-1. Both complexes display an intermediate stereochemistry between the two five-coordinated ones. The biological tests indicated that the two compounds exhibited superoxide scavenging capacity, intercalative DNA properties, and metallonuclease activity. Tests on various cell systems indicated that the two complexes neither interfere with the proliferation of Saccharomyces cerevisiae or BJ healthy skin cells, nor cause hemolysis in the active concentration range. Nevertheless, the compounds showed antibacterial potential, with complex (2) being significantly more active than complex (1) against all tested bacterial strains, both in planktonic and biofilm growth state. Both complexes exhibited a very good activity against B16 melanoma cells, with a higher specificity being displayed by compound (1). Taken together, the results indicate that complexes (1) and (2) have specific biological relevance, with potential for the development of antitumor or antimicrobial drugs.
APA, Harvard, Vancouver, ISO, and other styles
27

Guthrie, J. Peter, Roger T. Gallant, and Michael C. Jennings. "Preparation and characterization of bicyclic amide acetals and monothioacetals." Canadian Journal of Chemistry 82, no. 2 (February 1, 2004): 268–78. http://dx.doi.org/10.1139/v03-204.

Full text
Abstract:
We have prepared and characterized new examples of 5-substituted-1-aza-4,6-dioxabicyclo[3.3.0]octanes (bicyclic amide acetals) and examples of the new heterocyclic system, 5-substituted-1-aza-4-oxa-6-thiabicyclo[3.3.0]octanes (bicyclic amide monothioacetals). Detailed analysis of NMR coupling constants and X-ray structure determination for an example of each class of compound established the stereochemistry and conformation of these ring systems.Key words: bicyclic amide acetals, preparation, coupling constants, X-ray structure.
APA, Harvard, Vancouver, ISO, and other styles
28

K, Murugavel, Amirthaganesan S, Balasankar T, and Sabapathy mohan RT. "Synthesis of 4, 5-Dihydro-N(2)-Phenylindazole from Diversely Substituted Cyclic-β-Keto Esters and Its Structural Analysis." ECS Transactions 107, no. 1 (April 24, 2022): 1711–21. http://dx.doi.org/10.1149/10701.1711ecst.

Full text
Abstract:
To achieve the N-phenyl tetrahydroindazoles, t(3)-aryl-r(2),c(4)-bis(isopropoxycarbonyl)-c(5)-hydroxy-t(5)-methylcyclohexanones were treated with phenylhydrazine. Characterizations reveal the resultant products are respective N-phenyl dihydroindazoles. The reaction has been taken place in regioselctive manner. Plausible mechanism was proposed for the regioselective formation of dihydroindazoles with the phenyl substituent at N(2) position. Dehydration of hydroxyl group at C-6 position results double bond formation at C(6)–C(7). Besides, an investigation about the prior attempts which are unsuccessful for the synthesis of 2-phenylindazoles from a few cylic-β-keto esters has been discussed. Synthesized compounds were characterized by IR, One and Two dimensional NMR spectra. For all the synthesized compounds 7-13, 1H and 13C NMR spectra was recorded. HMBC and HSQC spectra recorded for a representative compound 7. HMBC spectrum also recorded for compound 8. Stereochemistry of the cyclohex-3-ene ring part in the dihydroindazole is in half chair form, where as in tetrahydroindazole, cyclohexane ring part is in normal chair conformation. Key Words: Dihydroindazole, phenylindazole, substituted indazoles, fused heterocycles, one and two dimensional NMR.
APA, Harvard, Vancouver, ISO, and other styles
29

Vrábel, Viktor, Július Sivý, Peter Šafař, and Štefan Marchalín. "Crystal and molecular structure of (9aS,10S)-6-Oxo-6,7,8,9,9a,10-hexahydro-4H-thieno-[2,3-b]quinolizin-10-yl acetate." Acta Chimica Slovaca 9, no. 2 (October 1, 2016): 180–83. http://dx.doi.org/10.1515/acs-2016-0030.

Full text
Abstract:
Abstract The title compound, C13H15NO3S, is a chiral molecule with two stereogenic centres. Its absolute configuration was derrived from the synthesis and confirmed by structure determination. The expected stereochemistry of atoms C5 and C6 was confirmed to be S. The central N-heterocyclic rings are not planar and adopt a half-chair conformation. A calculation of least-squares planes showed that these rings are puckered in such a manner that the five atoms C1, C2, C3, C5 and N1 (second ring: N1, C6, C7, C10 and C11) are planar, while atoms C4 (C5) are displaced from these planes with the out-of-plane displacement of 0.582 (3) Å and 0,666 (2) Å in the second ring, respectively. Dihedral angle between the planes of the central N-heterocyclic rings is 40.0 (1)°. Crystal structure is stabilized by C—H···O hydrogen interactions.
APA, Harvard, Vancouver, ISO, and other styles
30

Orysyk, Svitlana, Vasyl Pekhnyo, Viktor Orysyk, Yuri Zborovskii, Polina Borovyk, and Vovk Mykhailo. "FUNDAMENTAL ASPECTS OF THE COORDINATION CHEMISTRY OF TRANSITION METALS WITH FUNCTIONALLY SUBSTITUTED THIOAMIDES (PART 1)." Ukrainian Chemistry Journal 88, no. 2 (March 25, 2022): 85–115. http://dx.doi.org/10.33609/2708-129x.88.02.2022.85-115.

Full text
Abstract:
The influence of competitive coordination, a tautomeric form of functionally substituted thioamides, conditions of synthesis and nature of the metal on the course of the reaction and structure of mono-, bi, and polynuclear complexes of 3d, 4d-metals is considered based on results obtained in the Department of "Chemistry of Complex Compounds" of the V.I. Vernadsky Institute of General and Inorganic Chemistry NAS of Ukraine, together with the staff of the Department of “Chemistry of Heterocyclic Compounds” of the Institute of Organic Chemistry NAS of Ukraine. The influence of ligand denticity, as well as conditions of complex formation on the structure of obtained complexes and their polymorphic modifications, was studied based on the reaction of d-metals with functionally substituted N, S- and O, N, S-containing thioamides. In addition, it is proved the influence of tautomeric forms of thioamides on the stereochemistry of coordination polyhedra: it is found that the thionic tautomeric form promotes the transposition of thioureas, while the thiol form promotes its cis-position in the square-planar of a polyhedron of 3d, 4d-metals in the structure of complexes. However, it was found that the thion tautomeric form leads to the formation of octahedral, while the thiol form to the square-planar of coordination nodes in complexes of Cu(II) and Ni(II), which are characterized by a change in coordination polyhedra (from square-planar and tetrahedron to octahedron) that depending on the strength of the ligand field. It is obvious that this effect of tautomeric forms of thioamides is associated with the formation of a conjugate system of double bonds in their molecules. In this case, the transition of thioamide to thiol form depends on the pH and the nature of the organic solvent: in a weakly alkaline medium or polar organic solvent (pyridine, chloroform) there is a shift of equilibrium towards to the dominance of thiol tautomeric form. It was found that the thionic tautomeric form of thioamides (depending on pH and substituent composition) reacts with metal salts mainly in neutral form or in the monoanionic form, forming complexes of molecular or ionic nature, while thiol form reacts in the form of dianion, forming complexes preferably anionic type. Ionic compounds are usually soluble or sparingly soluble in water in low concentrations (10-3–10-5 mol/l), while compounds of the molecular type are soluble only in DMSO and DMF. It is shown that the stereoselective synthesis of various ligand complexes is carried out mainly in three ways: 1) by the interaction of the initial components in the corresponding stoichiometry. In this case, the vacancy in the metal environment is occupied by either the anions of the starting metal salt (Hal-, SO42-, NO3-, CH3COO-, etc.) or other organic molecules (triphenylphosphine, pyridine, etc.); 2) carrying out parallel reactions (hydrolysis and oxidation of thioureas), which lead to participation in the coordination of by-products of the reaction; 3) carrying out reactions with intraligand rearrangements, which leads to the cyclization of organic ligands and coordination of the products of their transformation to the central metal ion. However, it was found that hydrolysis / oxidation or intraligand cyclization of substituted polydentate thioamides can occur both under the action of synthesis conditions and under the action of complexing metals as promoters of organic reactions. It was found that depending on the temperature and time of interaction of the starting reagents, different polymorphic modifications of complexes (triclinic or monoclinic) are formed, which differ in packing density and the nature of intermolecular interactions. As a result, such polymorphic modifications have different solubilities in water, which is important for the controlled synthesis of appropriate structures and their practical application.
APA, Harvard, Vancouver, ISO, and other styles
31

Dembitsky, V. M., G. A. Tolstikov, and M. Srebnik. "Boranes in Organic Chemistry 2. β-Aminoalkyl- and β-sulfanylalkylboranes in organic synthesis." Eurasian Chemico-Technological Journal 4, no. 3 (June 30, 2017): 153. http://dx.doi.org/10.18321/ectj528.

Full text
Abstract:
<p>Problems on using of β-aminoalkyl- and β-sulfanylalkylboranes in organic synthesis are considered in this review. The synthesis of boron containing a-aminoacids by Curtius rearrangement draws attention. The use of β-aminoalkylboranes available by enamine hydroboration are described. Examples of enamine desamination with the formation of alkenes, aminoalcohols and their transformations into allylic alcohol are presented. These conversions have been carried out on steroids and nitrogen containing heterocyclic compounds. The dihydroboration of N-vinyl-carbamate and N-vinyl-urea have been described. Examples using nitrogen and oxygen containing boron derivatives for introduction of boron functions were presented. The route to borylhydrazones by hydroboration of enehydrazones was envisaged. The possibility of trialkylamine hydroboration was shown on indole alkaloids and 11-azatricyclo-[6.2.1<sup>1,8</sup>0<sup>2,7</sup>]2,4,6,9-undecatetraene examples. The synthesis of β-sulfanyl-alkylboranes by various routes was described. The synthesis of boronic thioaminoacids was carried out by free radical thiilation of dialkyl-vinylboronates. Ethoxyacetylene has been shown smoothly added 1-ethylthioboracyclopentane. Derivatives of 1,4-thiaborinane were readily obtained by divinylboronate hydroboration. Dialkylvinylboronates react with mercaptoethanol with the formation of 1,5,2-oxathioborepane derivatives. Stereochemistry of thiavinyl esters hydroboration leading to stereoisomeric β-sulfanylalkylboranes are discussed. Examples of radical thiilation of various structural types vinylboronates were presented. In particular, 1,3,2-dioxaborinanes and 1,3,2-dioxaborolanes, containing by boron atom vinyl-, propenyl-, isopropenylor isopropylidene substituents have been used. Thiilation has been achieved by use of alkylmercaptanes, as well as mercaptamine derivatives. Alkylmercaptanes were able to replace the bromine substituent in tris-(2-bromoctyl)-borane. Dialkylvinylborates have been added hydrosulfite with the formation of 2-boronoethane sulfuric acids. A lot of examples of radical thiilation of vinylboronic acid dialkyl esters with mercaptoacids are presented. Under the azaisobutyric acid dinitryle conditions thioglycolic, β-mercaptopropionic, 2-mercaptoamberic acids and their esters as well as cysteine were added. Vinyl-, propenyl- and isopropenyldioxaborolanes were also participated in the thiilation with the formation of acetic, propionic or amberic acid thioethanoboronates. The high reactivity of B,B,B-trivinyl-N,N,N-triphenylborazine in the reaction with thiophenol, leading to B-tris-(phenylmercaptoethyl)-N-phenylborazine was shown. The problems of asymmetric hydroboration leading to chiral β-sulfanylalkylboranes were discussed briefly. In particular, an example, including dihydro-thiophene hydroboration, leading to (+)-R-thiofan-3-yl-diisopinocamphenylborane, and the interaction with acetaldehyde with the formation of (+)-R-3-thiophanyl-diethoxyborane was implemented. The reaction with 3,4-dihydrothiapyrane proceeds analogously. A synthetic route to sulfono-norbornen-boronic acid esters by Diels-Alder reaction of cyclopentadiene with arylsulfanyl-vinylboronic acid esters has been discussed.</p>
APA, Harvard, Vancouver, ISO, and other styles
32

Sivý, Július, Peter Šafář, and Jozefína Žúžiová. "Crystal, molecular and electronic structure of (5S,11R,11aS)-11-hydroxy-5-methyl-1,2,3,4,5,6,11,11a-octahydropyrido[1,2-b]isoquinolin-5-ium iodide." Acta Chimica Slovaca 11, no. 2 (October 1, 2018): 94–98. http://dx.doi.org/10.2478/acs-2018-0014.

Full text
Abstract:
Abstract The title compound, C14H20INO, is a molecule with three stereogenic centres. It absolute configuration was derived from the synthesis and confirmed by structure determination (AD, Flack (Parsons’) parameter: 0.031 (8)). The expected stereochemistry of atoms N1 was confirmed to be S, C5 was confirmed to S, C6 was confirmed to R. The central N-heterocyclic ring is not planar and adopts a half-chair conformation. A calculation of least-squares planes showed that these rings are puckered in such a manner that the five atoms: C5, C6, C7, C12 and C13 (the second ring: C1, C2, C3, C4, C5 and N1) are planar, while atom N1 is displaced from these plane with the out-of-plane displacement of −0.694 (4) and −0.670 (5) Å in the second ring, respectively. Dihedral angle between the planes of the central N-heterocyclic rings is 23.4 (2)°. Crystal structure is also stabilized by C—H···O hydrogen interactions.
APA, Harvard, Vancouver, ISO, and other styles
33

Chouchène, Nourhène, Amani Toumi, Sarra Boudriga, Hayet Edziri, Mansour Sobeh, Mohamed A. O. Abdelfattah, Moheddine Askri, et al. "Antimicrobial Activity and DFT Studies of a Novel Set of Spiropyrrolidines Tethered with Thiochroman-4-one/Chroman-4-one Scaffolds." Molecules 27, no. 3 (January 18, 2022): 582. http://dx.doi.org/10.3390/molecules27030582.

Full text
Abstract:
A novel series of 14 spiropyrrolidines bearing thiochroman-4-one/chroman-4-one, and oxindole/acenaphthylene-1,2-dione moieties were synthesized and characterized by spectroscopic techniques, as well as by three X-ray diffraction studies, corroborating the stereochemistry. Quantum chemical calculations studies, using the DFT approach, were performed to rationalize the stereochemical outcome. These N-heterocycles were evaluated for their antibacterial and antifungal activities against some pathogenic organisms. Several compounds displayed moderate to excellent activity towards the screened microbe strains in the study compared to Amoxicillin (AMX), Ampicillin (AMP), and Amphotericin B. Furthermore, a structural activity relationship (SAR) was established considering the synthesized compounds. Pharmacokinetic studies reveal that these derivatives exhibit an acceptable predictive ADMET profile (Absorption, Distribution, Metabolism, Excretion and Toxicity) and good drug-likeness.
APA, Harvard, Vancouver, ISO, and other styles
34

Küppers, Horst, Karl-F. Hesse, Ulrike Ashauer-Holzgrabe, Rolf Haller, and Roland Boese. "Stereochemistry of Substituted Isomeric 3-Oxa-7-aza-bicyclo[3.3.1]nonan-9-ones." Zeitschrift für Naturforschung B 42, no. 2 (February 1, 1987): 221–28. http://dx.doi.org/10.1515/znb-1987-0217.

Full text
Abstract:
Abstract Two isomers of 7-methyl-9-oxo-2,4-diphenyl-3-oxa-7-aza-bicyclo[3.3.1]nonan-1,5-ethyl dicarboxylate (1a and 1b) were obtained by condensation of 2,6-diphenyl-1-oxa-4-oxo-cyclohexan-3,5-ethyl dicarboxylate with methylamine and formaldehyde. Their crystal structures were determined by X-ray diffraction. They crystallize in the triclinic space group P1̄ with (for 1a) a = 12.907(5), b = 11.223(4), c = 8.993(4) Å, α = 105.82(4), β = 100.14(5), γ = 97.35(4)°, and (for 1b) a = 16.400(7), b = 13.062(4), c = 11.336(2) Å, α = 94.19(3), β = 94.74(3), γ = 102.56(4)°. This investigation has shown that isomer 1a has the boat-chair conformation, and isomer 1b has the chair-chair conformation. The formation of la causes a configurational change of the phenyl substituents. The two species are characterized by NMR spectroscopy. - Another comparable bicyclononanone with a bulky substituent at the nitrogen atom has been synthesized and was investigated spectroscopically. This compound should have chair-boat conformation (with the boat conformation in the N-heterocyclic ring) whereas 1a has the boat conformation in the O-heterocyclic ring.
APA, Harvard, Vancouver, ISO, and other styles
35

Fukasawa, Sota, Tatsuya Toyoda, Ryohei Kasahara, Chisato Nakamura, Yuuki Kikuchi, Akiko Hori, Gary J. Richards, and Osamu Kitagawa. "Catalytic Enantioselective Synthesis of N-C Axially Chiral N-(2,6-Disubstituted-phenyl)sulfonamides through Chiral Pd-Catalyzed N-Allylation." Molecules 27, no. 22 (November 13, 2022): 7819. http://dx.doi.org/10.3390/molecules27227819.

Full text
Abstract:
Recently, catalytic enantioselective syntheses of N-C axially chiral compounds have been reported by many groups. Most N-C axially chiral compounds prepared through a catalytic asymmetric reaction possess carboxamide or nitrogen-containing aromatic heterocycle skeletons. On the other hand, although N-C axially chiral sulfonamide derivatives are known, their catalytic enantioselective synthesis is relatively underexplored. We found that the reaction (Tsuji–Trost allylation) of allyl acetate with secondary sulfonamides bearing a 2-arylethynyl-6-methylphenyl group on the nitrogen atom proceeds with good enantioselectivity (up to 92% ee) in the presence of (S,S)-Trost ligand-(allyl-PdCl)2 catalyst, affording rotationally stable N-C axially chiral N-allylated sulfonamides. Furthermore, the absolute stereochemistry of the major enantiomer was determined by X-ray single crystal structural analysis and the origin of the enantioselectivity was considered.
APA, Harvard, Vancouver, ISO, and other styles
36

Vandresen, Fabio, Sabrina Alencar de Almeida-Batista, Maria Eduarda Bueno Caldeira, Richard de Albuquerque Felizola Romeral, Celso Vataru Nakamura, Ana Lucia Tasca Góes Ruiz, and Cleuza Conceição da Silva. "Antitumor and antileishmanial activities of limonene-thiosemicarbazones bearing heterocycles nucleous." Research, Society and Development 11, no. 5 (March 31, 2022): e11711528152. http://dx.doi.org/10.33448/rsd-v11i5.28152.

Full text
Abstract:
In the present study, we provided the synthesis of a series of R-(+)- and S-(-)-limonene-based thiosemicarbazones containing different pentacyclic heterocyclic nucleus moiety focused in the search of novel antitumor and antileishmanial agents. In the antitumor assay, the derivative imidazole of S-(-)-limonene 8 was the most active compound, especially for U-251, UACC-62 and K562 human tumor cell lines with GI50 ranging from 1.0 to <0.25 µg.mL-1. On the other hand, the imidazole-thiosemicarbazone of R-(+)-limonene 4 was the most promising derivative against the promastigote form of L. amazonensis (IC50=5.9µM). Meanwhile, thiosemicarbazones without limonene moiety (9-12) showed the lowest activities in the biological assays performed. The results demonstrated the influence of the lipophilic molecular character and stereochemistry of chiral monoterpene on the evaluated activities.
APA, Harvard, Vancouver, ISO, and other styles
37

Martins, Francisco A., Josué M. Silla, and Matheus P. Freitas. "Conformational impact of structural modifications in 2-fluorocyclohexanone." Beilstein Journal of Organic Chemistry 13 (August 24, 2017): 1781–87. http://dx.doi.org/10.3762/bjoc.13.172.

Full text
Abstract:
2-Haloketones are building blocks that combine physical, chemical and biological features of materials and bioactive compounds, while organic fluorine plays a fundamental role in the design of performance organic molecules. Since these features are dependent on the three-dimensional chemical structure of a molecule, simple structural modifications can affect its conformational stability and, consequently, the corresponding physicochemical/biological property of interest. In this work, structural changes in 2-fluorocyclohexanone were theoretically studied with the aim at finding intramolecular interactions that induce the conformational equilibrium towards the axial or equatorial conformer. The interactions evaluated were hydrogen bonding, hyperconjugation, electrostatic and steric effects. While the gauche effect, originated from hyperconjugative interactions, does not appear to cause some preferences for the axial conformation of organofluorine heterocycles, more classical effects indeed rule the conformational equilibrium of the compounds. Spectroscopic parameters (NMR chemical shifts and coupling constants), which can be useful to determine the stereochemistry and the interactions operating in the series of 2-fluorocyclohexanone derivatives, were also calculated.
APA, Harvard, Vancouver, ISO, and other styles
38

Pohl, Radek, Jan Sýkora, Petr Maloň, Stanislav Böhm, Bohumil Kratochvíl, and Josef Kuthan. "Sterically Crowded Heterocycles. XIII. An Insight Into the Absolute Stereochemistry of Atropisomeric (Z)-3-(Imidazo[1,2-a]pyridin-3-yl)prop-2-en-1-ones." Collection of Czechoslovak Chemical Communications 65, no. 10 (2000): 1643–52. http://dx.doi.org/10.1135/cccc20001643.

Full text
Abstract:
The absolute configuration of the atropisomeric (Z)-3-(5-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one was evaluated to be R for the dextrorotatory and S for the laevorotatory enantiomers. The assignment is based on their two-step syntheses via atropodiastereoisomeric carbamates prepared from the corresponding atropodiastereoisomeric alcohols with (R)-(+)-α-phenylethyl isocyanate and by a complete X-ray space analysis of the quaternary triiodide obtained from the (R)-(+)-enantiomer. CD spectra and PM3 calculated heats of formation for selected compounds are discussed in relation to the found molecular configurations.
APA, Harvard, Vancouver, ISO, and other styles
39

Das, Aparna, Ram Naresh Yadav, and Bimal Krishna Banik. "Conceptual design and cost-efficient environmentally Benign synthesis of beta-lactams." Physical Sciences Reviews, May 4, 2022. http://dx.doi.org/10.1515/psr-2021-0088.

Full text
Abstract:
Abstract Stereoselective preparation of diverse trans and cis β-lactams following different experimental conditions are executed. A variety of circumstances are critically analyzed. It has been found that the stereochemistry of the products depends on a number of parameters including the conditions of the procedures, composition of the Schiff bases and acid chlorides or equivalents, method of addition of the reactants, temperature of the process and nature of the media. Using some of the compounds and methods as described herein, a number of useful chemical transformations for the preparation of heterocycles are achieved. These methods include indium-catalyzed glycosylation of amino β-lactams, preparation of pyrrole-substituted β-lactams, cycloaddition with sterically congested Schiff bases towards β-lactams, Michael reaction for the preparation of polycyclic oxazepenes and synthesis of two chiral isomers of the thienamycin side chain. Most of the products are obtained stereospecifically and in optically active forms. Many reactions described here are catalytic and therefore, these are environmentally friendly.
APA, Harvard, Vancouver, ISO, and other styles
40

LEVAI, A., A. SZOELLOSY, and G. TOTH. "ChemInform Abstract: Fused Heterocycles. Part 2. Synthesis and Stereochemistry of Benzopyrano[4,3-c]pyrazolines and Related Compounds." Chemischer Informationsdienst 17, no. 15 (April 15, 1986). http://dx.doi.org/10.1002/chin.198615089.

Full text
APA, Harvard, Vancouver, ISO, and other styles
41

Li Petri, Giovanna, Maria Valeria Raimondi, Virginia Spanò, Ralph Holl, Paola Barraja, and Alessandra Montalbano. "Pyrrolidine in Drug Discovery: A Versatile Scaffold for Novel Biologically Active Compounds." Topics in Current Chemistry 379, no. 5 (August 10, 2021). http://dx.doi.org/10.1007/s41061-021-00347-5.

Full text
Abstract:
AbstractThe five-membered pyrrolidine ring is one of the nitrogen heterocycles used widely by medicinal chemists to obtain compounds for the treatment of human diseases. The great interest in this saturated scaffold is enhanced by (1) the possibility to efficiently explore the pharmacophore space due to sp3-hybridization, (2) the contribution to the stereochemistry of the molecule, (3) and the increased three-dimensional (3D) coverage due to the non-planarity of the ring—a phenomenon called “pseudorotation”. In this review, we report bioactive molecules with target selectivity characterized by the pyrrolidine ring and its derivatives, including pyrrolizines, pyrrolidine-2-one, pyrrolidine-2,5-diones and prolinol described in the literature from 2015 to date. After a comparison of the physicochemical parameters of pyrrolidine with the parent aromatic pyrrole and cyclopentane, we investigate the influence of steric factors on biological activity, also describing the structure–activity relationship (SAR) of the studied compounds. To aid the reader’s approach to reading the manuscript, we have planned the review on the basis of the synthetic strategies used: (1) ring construction from different cyclic or acyclic precursors, reporting the synthesis and the reaction conditions, or (2) functionalization of preformed pyrrolidine rings, e.g., proline derivatives. Since one of the most significant features of the pyrrolidine ring is the stereogenicity of carbons, we highlight how the different stereoisomers and the spatial orientation of substituents can lead to a different biological profile of drug candidates, due to the different binding mode to enantioselective proteins. We believe that this work can guide medicinal chemists to the best approach in the design of new pyrrolidine compounds with different biological profiles.
APA, Harvard, Vancouver, ISO, and other styles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography