ChemInform Abstract: PYRIMIDINE DERIVATIVES PART 48, PMR-STUDIES ON SIGMA-ADDUCTS OF HETEROCYCLIC SYSTEMS WITH NUCLEOPHILES PART 5, (1)H NMR STUDIES OF SIGMA-ADDUCTS OF PTERIDINE AND SOME OF ITS DERIVATIVES IN LIQUID AMMONIA

The 6-N(CH3)3-6-CB9H11 carbaborane reacts with sodium in liquid ammonia with the formation of 6-CB9H12- which was used as a starting compound for preparing the 4-CB8H14, 9-L-6-CB9H13 (L = (CH3)2S, CH3CN and P(C6H5)3), 1-(η5-C5H5)-1,2-FeCB9H10-, and 2,3-(η5-C5H5)2-2,31-Co2CB9H10- carboranes. The 4-CB8H14 compound was dehydrogenated at 623 K to give 4-(7)-CB8H12 carborane. Base degradation of 6-N(CH3)3-6-CB9H11 in methanol resulted in the formation of 3,4-μ-N(CH3)3CH-B5H10. The structure of all compounds was proposed on the basis of their 11B and 1H NMR spectra and X-ray diffraction was used in the case of the transition metal complexes.

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1H NMR Conformational Studies in Water of Angiotensin II Analogues Modified at the N- and C-Termini: Interactions of the Aromatic Side Chains and Folding of the N-Terminal Domain

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19942523 ◽

1994 ◽

Vol 59 (11) ◽

pp. 2523-2532 ◽

Cited By ~ 4

Author(s):

John Hondrelis ◽

John Matsoukas ◽

George Agelis ◽

Paul Cordopatis ◽

Ning Zhou ◽

...

Keyword(s):

Shielding Effect ◽

Resonance Spectroscopy ◽

Nmr Studies ◽

Previous Suggestion ◽

Aminoisobutyric Acid ◽

H Nmr ◽

Neutral Ph ◽

Angiotensin Ii Analogues ◽

Proton Resonances ◽

Cosy Nmr

The conformation of [Sar1]angiotensin II in water at neutral pH has been examined by proton magnetic resonance spectroscopy at 400 MHz and in particular by comparing its 1H NMR spectral data with those of analogues modified at positions 1,4 and 6, namely [Sar1,Cha8]ANGII, [Des Asp1,Cha8]ANGII, [Aib1,Tyr(Me)4]ANGII, [Aib1,Tyr(Me)4,Ile8]ANGII, [N-MeAib1,Tyr(Me)4]ANGII, [N-MeAib1,Tyr(Me)4,Ile8]ANGII, ANGIII and [Sar1,Ile8]ANGII. Assignment of all proton resonances in these analogues was made possible by 2D COSY NMR experiments. The H-2 and H-4 protons for the histidine ring in [Sar1]ANGII, ANGII and ANGIII were shielded compared with the same protons in [Sar1,Ile8]ANGII, [Sar1,Cha8]ANGII and [Des Asp1,Cha8]ANGII; this shielding effect was not disturbed upon methylation of the tyrosine hydroxyl and/or replacement of residue 1 (sarcosine or aspartic acid) with aminoisobutyric acid (Aib) or N-methyl aminoisobutyric acid (N-MeAib). These data are consistent with our previous suggestion based on NMR studies in neutral DMSO that a characteristic folded conformation for ANGII previously observed in non-polar solvents can also be detected in water at neutral pH, but to a lesser degree.

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High field 1H NMR Studies of Sol-Gel Kinetics

MRS Proceedings ◽

10.1557/proc-73-157 ◽

1986 ◽

Vol 73 ◽

Cited By ~ 7

Author(s):

Bruce D. Kay ◽

Roger A. Assink

Keyword(s):

Equilibrium Distribution ◽

Sol Gel ◽

Nmr Studies ◽

H Nmr ◽

Rate Limiting Step ◽

Rate Of Hydrolysis ◽

Acid Catalyzed ◽

Product Species ◽

Rate Limiting ◽

Kinetics Of

ABSTRACTHigh resolution 1H NMR spectroscopy at high magnetic fields is employed to study the reaction kinetics of the Si(OCH3)4:CH3OH:H2O sol-gel system. Both the overall extent of reaction as a function of time and the equilibrium distribution of species are measured. In acid catalyzed solution, condensation is the rate limiting step while in base catalyzed solution, hydrolysis becomes rate limiting. A kinetic model in which the rate of hydrolysis is assumed to be independent of the adjacent functional groups is presented. This model correctly predicts the distribution of product species during the initial stages of the sol-gel reaction.

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Synthesis and Antibacterial Activity of New Spiro[thiadiazoline-(pyrazolo[3,4-d]pyrimidine)] Derivatives

Journal of Chemistry ◽

10.1155/2015/982404 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Mohammed El Fal ◽

Youssef Ramli ◽

Abdelfettah Zerzouf ◽

Ahmed Talbaoui ◽

Youssef Bakri ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antibacterial Activity ◽

Spectroscopic Data ◽

Heterocyclic Compounds ◽

Dipolar Cycloaddition ◽

Bacterial Strains ◽

Pyrimidine Derivatives ◽

H Nmr ◽

Biological Interest ◽

Mic Value

New heterocyclic compounds spiroderivatives of allopurinol of biological interest were prepared from allopurinol via thionation and 1,3-dipolar cycloaddition and were produced in high to excellent yields. These compounds were characterized on the basis of spectral and spectroscopic data (1H NMR,13C, IR, and MS). The antibacterial activity of the synthesized products was studied using bacterial strains:Staphylococcus aureus,Enterococcus faecalis,Escherichia coli, andPseudomonas aeruginosa. Compounds having an ethyl group showed the best activity with MIC value of 31.25 µg/mL againstStaphylococcus aureusandStreptococcus fasciens.

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Equilibrium thermodynamic studies for the formation of 1:1 complexes of CO and ethene with a rhodium(II) porphyrin metallo-radical

Canadian Journal of Chemistry ◽

10.1139/v01-052 ◽

2001 ◽

Vol 79 (5-6) ◽

pp. 854-856 ◽

Cited By ~ 9

Author(s):

Leah Basickes ◽

Andrew G Bunn ◽

Bradford B Wayland

Keyword(s):

Carbon Monoxide ◽

Complex Formation ◽

Equilibrium Thermodynamic ◽

Nmr Studies ◽

Thermodynamic Studies ◽

H Nmr ◽

Porphyrin Ligand ◽

The One ◽

Paramagnetic Shifts

Tetra(2,4,6 triisopropropyl phenyl)porphyrinatorhodium(II) ((TTiPP)RhII·1) is a persistent metal-centered radical with the odd electron in the rhodium(II) dz2 orbital. (TTiPP)RhII· forms 1:1 complexes with CO and CH2CH2 where the porphyrin ligand steric properties inhibit further reactions of the one-electron activated substrates. 1H NMR paramagnetic shifts at a series of temperatures are used in evaluating the thermodynamics for CO complex formation with 1 to form [(TTiPP)RhII(CO)]·2 (ΔH° = -5.5 ± 0.5 kcal mol-1; ΔS° = -9 ± 1 cal K-1 mol-1). Related 1H NMR studies show that the bonding of 1 with ethene is less favorable than CO.Key words: rhodium porphyrin, carbon monoxide, ethene, thermodynamics, complex formation, metal-centered radical.

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The synthesis of 11R- and 11S-HETE and of 11-R,S-HPETE methyl esters

Canadian Journal of Chemistry ◽

10.1139/v83-132 ◽

1983 ◽

Vol 61 (4) ◽

pp. 712-717 ◽

Cited By ~ 13

Author(s):

George Just ◽

Corinne Luthe ◽

Minh Tan Phan Viet

Keyword(s):

Methyl Esters ◽

Nmr Studies ◽

H Nmr ◽

Conformational Properties

Methyl 11R- and 11S-hydroxyeicosa-5Z,8Z,12E,14Z-tetraenoate (17R, 17S) (11-HETE) and the corresponding 11-hydroperoxide 19 (11-HPETE) have been prepared from readily available starting materials. The yields were approximately 25% for 11R,S-HETE, and 5% each for 11R- and 11S-HETE.Extensive 400 MHz 1H nmr studies of 17 (nOe difference, 2D J-resolved) were undertaken to confirm the structure. Some conformational properties are discussed.

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1H NMR Studies of Surfactants in Aqueous Solutions

Acta Physico-Chimica Sinica ◽

10.3866/pku.whxb20030723 ◽

2003 ◽

Vol 19 (07) ◽

pp. 675-680 ◽

Cited By ~ 9

Author(s):

Mao Shi-Zhen ◽

◽

Du You-Ru

Keyword(s):

Aqueous Solutions ◽

Nmr Studies ◽

H Nmr

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ChemInform Abstract: (19)F- AND (1)H-NMR STUDIES OF RING-FLUORINATED IMIDAZOLES AND HISTIDINES

Chemischer Informationsdienst ◽

10.1002/chin.197542053 ◽

1975 ◽

Vol 6 (42) ◽

pp. no-no

Author(s):

HERMAN J. C. YEH ◽

KENNETH L. KIRK ◽

LOUIS A. COHEN ◽

JACK S. COHEN

Keyword(s):

Nmr Studies ◽

H Nmr

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Chiral "basket handle" binaphthyl porphyrins: synthesis, catalytic epoxidation and NMR conformational studies

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424610002483 ◽

2010 ◽

Vol 14 (07) ◽

pp. 646-659 ◽

Cited By ~ 17

Author(s):

Eric Rose ◽

Emma Gallo ◽

Nicolas Raoul ◽

Léa Bouché ◽

Ariane Pille ◽

...

Keyword(s):

Time Scale ◽

Room Temperature ◽

Conformational Equilibrium ◽

Variable Temperature ◽

Conformational Exchange ◽

Iron Catalysts ◽

Nmr Studies ◽

Conformational Studies ◽

H Nmr ◽

Catalytic Epoxidation

Three "basket handle" porphyrins have been prepared by condensation of tetrakis-(α,β,α,β-2-aminophenyl)porphyrin atropoisomer with 1,1′-binaphthyl, 2,2′-dimethoxy, -3,3′-dicarbonylchloride, -3,3′-diacetylchloride and -3,3′-dipropanoylchloride. The epoxidation of styrene with the three iron catalysts, obtained after metalation of the free porphyrins, occurs with good yields and moderate ee up to 54%. These porphyrins showed unexpected conformational differences, as revealed by NMR spectroscopy. In particular, variable temperature NMR studies showed that the methoxy group in one of them undergoes intermediate conformational exchange on the 1H NMR time scale at room temperature. Lowering the temperature to -50 °C revealed the presence of four states in slow exchange on the NMR time scale. These results evidence a dynamic conformational equilibrium of the binaphthyl handles that adopt different, asymmetric positions with respect to the porphyrin plane.

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