Hetero[8]circulenes: synthetic progress and intrinsic properties

2020 ◽  
Vol 56 (100) ◽  
pp. 15605-15614
Author(s):  
Yoshihiro Miyake ◽  
Hiroshi Shinokubo
Keyword(s):  
Structural Features ◽  
Membered Ring ◽  
Synthetic Route ◽  
Intrinsic Properties ◽  
Ring Fusion ◽  
Electronic Nature ◽  
Peripheral Ring

Synthetic route for hetero[8]circulenes are classified into the annulative construction of eight-membered ring and the peripheral ring fusion of eight-membered ring. Post-transformation enables the tuning of structural features and electronic nature.

SYNTHESIS OF METHYL 4-ACETAMIDO-4-DEOXY-L-ERYTHROFURANOSIDE: A SUGAR WITH NITROGEN IN A FIVE-MEMBERED RING

1964 ◽  
Vol 42 (1) ◽  
pp. 20-24 ◽  
Author(s):  
W. A. Szarek ◽  
J. K. N. Jones
Keyword(s):  
Structural Features ◽  
Membered Ring

The synthesis of methyl 4-acetamido-4-deoxy-L-erythrofuranoside from D-ribose is described. The structural features that are believed to be necessary for the replacement of the ring oxygen of sugars by nitrogen are discussed.

scholarly journals SÍNTESE DE NOVOS 1,2,3-TRIAZÓIS INSPIRADOS NO SRPIN340 E AVALIAÇÃO DE SEUS EFEITOS EM LINHAGEM CELULAR DE GLIOBLASTOMA HUMANO

Química Nova ◽  
2021 ◽  
Author(s):  
Sara Sousa ◽  
Róbson Teixeira ◽  
Adilson Costa ◽  
Alex Aguiar ◽  
Victor Fonseca ◽  
...  
Keyword(s):  
Cell Viability ◽  
Cell Line ◽  
Treatment Time ◽  
Cycloaddition Reaction ◽  
Structural Features ◽  
Biological Evaluation ◽  
Membered Ring ◽  
Glioblastoma Cell Line ◽  
Human Glioblastoma ◽  
Human Glioblastoma Multiforme

SYNTHESIS OF NOVEL 1,2,3-TRIAZOLES INSPIRED ON THE SRPIN340 AND EVALUATION OF THEIR EFFECTS ON HUMAN GLIOBLASTOMA CELL LINE. It is herein described the synthesis of a series of thirty novel 1,2,3-triazole1,4-disubstituted compounds inspired on the known SRPKs inhibitor N-(2-(piperidin-1-yl)-5-(trifluoromethyl)phenyl)isonicotinamide (SRPIN340) and biological evaluation of them against human glioblastoma multiforme cell line U87MG. Starting with 1-fluoro2-nitro-4- (trifluoromethyl)benzene (1), the substances were prepared via a five-step synthetic route. The crucial step corresponded to the copper-catalyzed cycloaddition reaction between trifluoromethyl phenyl azides and different alkynes. In general, the compounds were obtained with good yields and they were characterized utilizing spectroscopic (IR and NMR) and spectrometric (HRMS) techniques. The evaluation of the synthesized compounds at three different treatment time (24 h, 48 h, and 72 h) and concentrations (50, 100, and 150 µmol L-1) revealed that five derivatives were capable of reducing cell viability by 50% after 72 h of treatment at the highest concentration. On the contrary, three derivatives significantly increased cell viability being this effect more pronounced after 48 h of treatment. In this regard, it stands out the compound 2-((1-(2-morpholino-5-(trifluoromethyl)phenyl)-1H-1,2,3-triazol4-yl)methyl)isoindoline-1,3-dione (7) which increased cell viability in approximately 300% after 48 h of treatment at 100 µmol L-1. The substances that increased cell viaiblity present as common structural features the presence of a saturated nitrogen-containing six-membered ring and carbonylated fragments.

scholarly journals Synthetic route towards 1,2,3,4-tetrahydroquinoxaline/piperidine combined tricyclic ring system

2021 ◽  
pp. 68-68
Author(s):  
Mihajlo Krunic ◽  
Ivana Jevtic ◽  
Jelena Penjisevic ◽  
Sladjana Kostic-Rajacic
Keyword(s):  
Heterocyclic System ◽  
Structural Features ◽  
Ring System ◽  
Synthetic Route ◽  
Amino Groups ◽  
Hofmann Rearrangement

The synthetic route toward novel tricyclic, nitrogen-containing system is disclosed. Three novel compounds possessing structural features of 1,2,3,4-tetrahydroquinoxaline and decahydropyrido[3,4-b]pyrazine are synthesized starting from readily available precursors in six or seven steps, of which the last three or four steps respectfully are diastereoselective. Key reaction steps include N-acylation, Hofmann rearrangement and ring-closing Buchwald-Hartwig reaction. Compounds trans-8, cis-12 and trans-12 are synthesized in order to prove that this novel, tricyclic system can be functionalized with various groups. Synthetic significance of this heterocyclic system lies in the possibility for the orthogonal functionalization of three different amino groups, allowing fine structural tuning.

New Methods for Functional Group Conversion

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Solid Phase ◽  
Scale Up ◽  
Membered Ring ◽  
Santa Barbara ◽  
University Of Kentucky ◽  
Ring Fusion ◽  
Fe Catalyst ◽  
Aqueous Base ◽  
The University ◽  
University Of Manchester

Yujiro Hayashi of Tokyo University of Science and Teruaki Mukaiyama of the Kitasato Institute developed (Chem. Lett. 2008, 37, 592) a reduction-oxidation method for converting primary, secondary (such as 1, with clean inversion) and tertiary alcohols to sulfides. Peter A. Crooks of the University of Kentucky found (Chem. Lett. 2008, 37, 528) that tetrabenzylpyrophosphate 5 was an effective agent for condensing an acid 4 with an amine 6 to give the amide 7. This protocol, that runs in near quantitative yield in an hour at room temperature, with all impurities readily removable by washing with aqueous base and aqueous acid, appears to be well-suited both for scale-up, and for solid-phase synthesis. Balchandra M. Bhanage of the University of Mumbai reported (Tetrahedron Lett. 2008, 49, 965) the reductive amination of aldehydes, including 8, and ketones to the corresponding amines, using H2 and an inexpensive Fe catalyst. André Charette of the Université de Montréal showed (J. Am. Chem. Soc. 2008, 130, 18) that the Hantzsch ester 12 , in the presence of Tf2O, reduced amides selectively to amines. Esters, epoxides, ketones, nitriles and alkynes were stable to these conditions. Matthew Tudge of Merck Rahway demonstrated (Tetrahedron Lett . 2008, 49, 1041) that Br2 in DME activated NaBH4 , allowing facile reduction of esters, including the congested diester 14, at ambient temperature. David J. Procter of the University of Manchester made (J. Am. Chem. Soc. 2008, 130, 1136) the remarkable observation that six-membered ring lactones such as 16 were reduced to the corresponding diol with SmI2 . Five-membered ring and seven-membered ring lactones were not reduced under these conditions. Bruce H. Lipshutz of the University of California, Santa Barbara devised (Organic Lett . 2008, 10, 289) a convenient and economical procedure for CuH, using Cu and an inexpensive ligand in catalytic amounts, with PMHS as the bulk reductant. The reduction of 18 presumably proceeds by electron transfer, as with dissolving metal reduction, delivering 19 with the more stable trans ring fusion. In the presence of t-BuOH as a proton source, the reduction goes on to the alcohol 20.

Symmetry-modified conformational mapping and classification of the medium rings from crystallographic data. IV. Cyclooctane and related eight-membered rings

1996 ◽  
Vol 52 (5) ◽  
pp. 882-891 ◽  
Author(s):  
F. H. Allen ◽  
J. A. K. Howard ◽  
N. A. Pitchford
Keyword(s):  
Principal Component ◽  
Membered Ring ◽  
Ring Fusion ◽  
Structural Database ◽  
And Cluster Analysis ◽  
Medium Rings ◽  
Energy Hypersurface ◽  
Ring Conformations ◽  
Potential Energy Hypersurface

Crystallographic observations of eight-membered ring conformations, retrieved from the Cambridge Structural Database, have been mapped and classified using symmetry-adapted deformation coordinates, principal component analysis and cluster analysis. Seven subsets of eight-membered rings, containing 11–32 conformational observations, have been analysed: cyclooctane (dataset 8C1), cyclooctene (8C2), cycloocta-1,3-diene (8C3), mono-exo-unsaturated carbocycles (8C4), monohetero (8A1), 1,5-dihetero (8A2) and 1,3,5,7-tetrahetero rings (8A3). The energetically preferred (by ~7 kJ mol−1) boat-chair form is adopted by 26 of the 32 examples of 8C1, although varying degrees of twist are induced by fusion to rings of sizes three, four and five. Crystallographic results for other subsets also populate the lower-energy areas of the appropriate potential energy hypersurface, but the analyses are complicated by the effects of ring fusion and by the small numbers of relevant crystal structures in some cases.

scholarly journals Mimicking Noncanonical Oxidations with Redox-Neutral Photocatalysis

2019 ◽  
Author(s):  
Zheng Huang ◽  
Jean-Philip Lumb
Keyword(s):  
Organic Synthesis ◽  
Structural Features ◽  
Membered Ring ◽  
Ring Formation ◽  
Radical Cyclizations ◽  
General Strategy ◽  
Sufficient Time ◽  
Lignan Biosynthesis

Noncanonical oxygenases are a family of Fe-containing enzymes that catalyze oxidative radical cyclizations. Despite creating key structural features that often define a natural product’s complexity, the mechanisms of these oxidations remain poorly understood and difficult to mimic. In this work, we show that noncanonical cyclizations from lignan biosynthesis can be recreated when presumed biosynthetic radicals are generated using photocatalysis. These conditions afford the ensuing electron rich radicals sufficient time to undergo challenging 5- or 11-membered ring formation that create the defining structural features of the highly oxidized lignans taiwankadsurins A, B and kadsuphilin N. By showing that these cyclizations can occur without enzymatic assistance, we provide a more general strategy for mimicking noncanonical transformations that should broaden their use in organic synthesis.

Interplay between steric and electronic factors in determining the strength of intramolecular N—H...O resonance-assisted hydrogen bonds in β-enaminones

2006 ◽  
Vol 62 (6) ◽  
pp. 1112-1120 ◽  
Author(s):  
Valerio Bertolasi ◽  
Loretta Pretto ◽  
Valeria Ferretti ◽  
Paola Gilli ◽  
Gastone Gilli
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Structural Features ◽  
Membered Ring ◽  
Resonance Assisted Hydrogen Bond ◽  
Electronic Resonance ◽  
Hydrogen Bonded

The crystal structures of five β-enaminones are reported: (2Z)-3-(benzylamino)-1,3-diphenyl-prop-2-en-1-one, (2Z)-3-(benzylamino)-3-(2-hydroxyphenyl)-1-phenyl-prop-2-en-1-one, (2Z)-3-(benzylamino)-3-(4-methoxyphenyl)-1-(3-nitrophenyl)-prop-2-en-1-one, 2-{1-[(4-methoxyphenyl)amino]ethylidene}cyclohexene-1,3-dione and 2-{1-[(3-methoxyphenyl)amino]ethylidene}cyclohexene-1,3-dione. The structures were analysed and compared with those of similar compounds in order to establish which factors determine the range (2.53–2.72 Å) of N...O hydrogen-bond distances in intramolecularly hydrogen-bonded β-enaminones. It has been shown that, beyond electronic resonance-assisted hydrogen-bond effects modulated by substituents, the necessary requirements to produce very short N—H...O hydrogen bonding are steric intramolecular repulsions, including the embedding of an enaminonic C—C or C—N bond in an aliphatic six-membered ring. By considering the structural features it is possible to expect the strength of N—H...O hydrogen bonds adopted by specific β-enaminones.

Design and synthesis of analogues of ionomycin

1994 ◽  
Vol 72 (6) ◽  
pp. 1500-1511 ◽  
Author(s):  
Thomas Q. Hu ◽  
Larry Weller
Keyword(s):  
Crystal Structure ◽  
Structural Features ◽  
Lipid Solubility ◽  
Carboxyl Group ◽  
Synthetic Route ◽  
Design And Synthesis ◽  
Coordination Sites ◽  
Physical Data ◽  
Oxygen Coordination

Based on the analysis of the crystal structure of the Ca2+ salt of ionomycin and the chemical and physical data on ionomycin, a number of ionomycin analogues have been synthesized to study the structural features affecting the Ca2+ binding and transport. Compounds 2, 3, and 4 were synthesized to study the effect of additional intramolecular oxygen coordination sites on Ca2+ transport. Compounds 5a–5d were prepared to study the effect of lipid solubility on Ca2+ binding and transport. Compounds 6a–6c were prepared to study the effect of the distance between the β-diketone and the carboxyl group on Ca2+ transport. A general synthetic route to these compounds has been developed. The key reactions in this route are the consecutive regioselective alkylations of the dianion of 2,4-pentanedione with the appropriate bromides.[Formula: see text]

THE CARBONYL STRETCHING BANDS IN THE INFRARED SPECTRA OF UNSATURATED LACTONES

1959 ◽  
Vol 37 (12) ◽  
pp. 2007-2022 ◽  
Author(s):  
R. N. Jones ◽  
C. L. Angell ◽  
T. Ito ◽  
R. J. D. Smith
Keyword(s):  
Infrared Spectra ◽  
Carbonyl Compounds ◽  
Structural Features ◽  
Membered Ring ◽  
Fermi Resonance ◽  
Fundamental Vibration ◽  
Conformational Isomers ◽  
Band Splitting ◽  
Carbonyl Band ◽  
Unsaturated Lactones

Certain types of unsaturated lactones exhibit two bands in the region of the spectrum associated with the C=O stretching vibrational mode. This is observed both in the infrared and Raman spectra.The infrared spectra of 23 simple saturated and unsaturated lactones have been examined in an attempt to determine the structural features with which this carbonyl band splitting is associated. It appears to be common to most unsaturated five- and six-membered ring lactones in which the double bond is conjugated with the carbonyl group, though one well-established exception has been observed. The relative intensities of the two bands are extremely sensitive to changes in the polarity of the solvent; they also vary reversibly with temperature but are independent of concentration.The splitting of the C=O stretching band is attributed to an intramolecular vibrational effect similar to that which occurs in cyclopentanone and in certain Δ2-cyclopentenone derivatives. Its possible dependence on Fermi resonance with the overtone of a lower lying fundamental vibration is discussed.Similar effects occur in other types of carbonyl compounds, such as benzoyl chloride and cyclic five-membered ring anhydrides, and care is needed to distinguish carbonyl band splitting of this kind from that associated with equilibria between conformational isomers.

Iron complex of a quadruply fused porphyrin: Synthesis, structure and redox properties

2020 ◽  
Vol 24 (01n03) ◽  
pp. 252-258
Author(s):  
Tomoya Ishizuka ◽  
Keiyu Komamura ◽  
Yuta Saegusa ◽  
Shogo Tanaka ◽  
Yoshihito Shiota ◽  
...  
Keyword(s):  
Differential Pulse ◽  
Iron Complex ◽  
X Ray Diffraction ◽  
Ring Fusion ◽  
H Nmr ◽  
Axial Ligands ◽  
Peripheral Ring ◽  
Controlled Potential ◽  
Bulk Electrolysis ◽  
Porphyrin Synthesis

An iron(II) complex of a quadruply ring-fused porphyrin (QFP), Fe-1, in which four mesityl groups were introduced at the periphery to improve the solubility in organic solvents, has been newly synthesized and characterized. In the pyridine solution, two pyridine molecules bind to the low-spin Fe[Formula: see text] center of Fe-1 as axial ligands to make the complex stable even under air. Characterization of Fe-1 was performed using 1H NMR spectroscopy, MALDI-TOF-MS spectrometry and single-crystal X-ray diffraction analysis. The 1H NMR signals of Fe-1 were observed in the diamagnetic region, reflecting the low-spin state of the FeII center. In the differential pulse voltammogram of Fe-1, three oxidation waves and four reduction waves were observed in pyridine; the first oxidation wave at -0.08 V vs. Fc/Fc[Formula: see text] can be ascribed to the oxidation process of the FeII center, FeII/FeIII, and other six waves can be assigned to the redox processes of the QFP ligand. Furthermore, the ESR measurement of 1e[Formula: see text]-reduced Fe-1 upon controlled-potential bulk electrolysis in pyridine exhibited a signal at [Formula: see text] = 2.003 with a well-resolved 45-line hyperfine splitting at room temperature, due to the coupling with four nitrogen nuclei and twelve hydrogen ones of the QFP ligand. This indicates that the ligand radical anion of Fe-1 is stabilized by delocalization of the spin density owing to the peripheral ring fusion and resultant expansion of the [Formula: see text]-conjugation.

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