Variation of the nuclear Overhauser effect in dimethylformamide with temperature

1970 ◽  
Vol 48 (3) ◽  
pp. 512-513 ◽  
Author(s):  
J. K. Saunders ◽  
R. A. Bell
Keyword(s):  
High Field ◽  
Room Temperature ◽  
Nuclear Overhauser Effect ◽  
Low Field ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects

The nuclear Overhauser effects at the formyl proton of dimethylformamide have been measured at and above room temperature. At 90° separate irradiation of the high field and low field methyl signals results in equal nuclear Overhauser effects from both methyls.

The conformational analysis of piriprost, an inhibitor of leukotriene synthesis, based on high-field nuclear magnetic resonance studies

1985 ◽  
Vol 63 (10) ◽  
pp. 2614-2617 ◽  
Author(s):  
George Kotovych ◽  
Helmut Beierbeck ◽  
David Salmon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Field ◽  
Nuclear Overhauser Effect ◽  
Magnetic Resonance Studies ◽  
Effect Data ◽  
Overhauser Effect ◽  
Phenyl Rings ◽  
Nuclear Overhauser ◽  
Cyclopentene Ring

The analysis of proton nuclear Overhauser effect data for piriprost, (6,9-deepoxy)-6,9-(phenylimino)-Δ6,8 prostaglandin I1, indicates that the cyclopentene ring has the 11E conformation. A long-range nOe effect indicates that the α-chain is folded near the pyrrole and the phenyl rings.

Studies of Australian Soft Corals. XLVI. New Diterpenes From a Briareum Species (Anthozoa, Octocorallia, Gorgonacea)

1989 ◽  
Vol 42 (10) ◽  
pp. 1705 ◽  
Author(s):  
BF Bowden ◽  
JC Coll ◽  
IM Vasilescu
Keyword(s):  
High Field ◽  
Nuclear Overhauser Effect ◽  
Soft Corals ◽  
Overhauser Effect ◽  
Relative Stereochemistry ◽  
Nuclear Overhauser ◽  
New Compounds

The structures and relative stereochemistry of nine new briaran -based diterpenes from a Briareum species have been deduced from 2-D n.m.r. experiments at high field, and nuclear Overhauser effect experiments. The new compounds are (1R*2R*,3R*,5Z,7S*,8S*,9S*,10S*,11R*,-12S*,14S*,17R*)-2,3,14-triacetoxy-8,17:11,12-bisepoxy-9-hydroxybriar-5-en-18-one (5), (1R* ,2R* ,3R* ,5Z*,7S*,8S* ,9S*,10S*,11R*,12S*, 14S*, 17R*)-3,14-diacetoxy-2-butyryloxy-8,17:11,12-bisepoxy-9-hydroxybriar-5-en-18-one (6),(1R*,2R*,3R*,5Z,7S*,8S*,9S*,10S*,11R*,12S*,14S)-2,3,14-triacetoxy-11,12-epoxybriara-5,8(17)-dien-18-one(17),(1S*,2S*,4R*,5Z,7S*,8S*,9S*,10S*,2,4,9.12-tetraacetoxy-8,17-epoxy-11-hydroxybriara-5,13-dien-18-one (8),(1S*, 2S*,4R*, 5Z,7S*,8S*,9S*,10S*, 11S*, 12R*,13Z,17R*)-2,4,9-triacetoxy-8,17-epoxy-11,12-dihydroxybriara-5,13-dien-18-one (9), (1S *,2S*,4R*,5Z,7S*,8S*,9S*,10S*, 11S *,12R*,13Z,17R*)-2,4,9,12-tetraacetoxy-8,17-epoxy-11-hydroxybriara-5,13-dien-18-one(10),(1Si,2S*,5Z,7S',8S*,-9S*,10S*,11R*,12R*,13Z,17R*)-2,12-diacetoxy-8,17-epoxy-9-hydroxybriara-5,13-dien-18-one(ll), (1R*,2R*,3Si,5Z,7S* ,8S* ,9S* ,10S* ,11Z,14S*,17R*)-2,14-diacetoxy-3-butyryloxy-8,17-epoxy-9-hydroxybriara-5,11-dien-18-one (12) and (1R *,2R*,3S*,5Z,7S*,8S*,9S*,10S*,11Z,-14S',17R*)-2,3,14-triacetoxy-8,17-epoxy-9-hydroxybriara-5,11-dien-18-one (13). In addition to the nine new briaran derivatives, the same coral afforded two cladiellane derivatives (1R*,4R*,5S*,6R*,8R*,12R*,13R*,14R*)-cladiellane-4,8,12-triol (14) and its 4-acetoxy derivative (15). Aknowncembranoid diterpene (1R *,4R*,ZE,7E,l1E)-cembra-2,7,11-trien-4-ol(21) wasalso isolated together with an unprecedented perhydrophenanthrene-based diterpene (20): (1R *, 1aR*,4S*,4aR*,5aR*,8aR*)-4-isopropyl-l,8a-dimethyl-5-methylenetetradecahydrophenanthren-1-ol. The extraordinary biosynthetic ability of soft corals from the genus Briareum is once more revealed.

Analysis of short interproton distances in proline peptides as a guide in the interpretation of nuclear Overhauser effects

1988 ◽  
Vol 53 (11) ◽  
pp. 2801-2809 ◽  
Author(s):  
Chandrashekharan Ramakrishnan ◽  
Ramanathan Sowdhamini ◽  
Padmanabhan Balaram
Keyword(s):  
Nuclear Overhauser Effect ◽  
Model Systems ◽  
Pyrrolidine Ring ◽  
Ramachandran Map ◽  
Overhauser Effect ◽  
Ring Puckering ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Interproton Distances ◽  
Helical Region

The conformational dependence of interproton distances in model proline peptides has been investigated in order to facilitate interpretation of the results of Nuclear Overhauser Effect (NOE) studies on such peptides. For this purpose two model systems, namely, Ac-Pro-NHMe and Ac-Pro-X-NHMe have been chosen and used. In the former, short interproton distances detectable in NOE experiments permit a clear distinction between conformations with Pro ψ = -300 (helical region) and those in which ψ is around 1200 (polyproline region). For the latter, the variation of distances between the protons of methyl amide and the Pro ring have been studied by superimposing on the Ramachandran map in the (φ3, ψ3) plane. The results show that β-turns and non-β-turn conformations can be readily distinguished from NOE data and such long range NOEs should be detectable for specific non-β-turn conformations. NOEs involving Cβ and Cγ protons are particularly sensitive to the state of pyrrolidine ring puckering.

1H NMR studies of [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in dimethylsulfoxide by nuclear Overhauser effect (NOE) enhancement spectroscopy: cis-trans Isomerism of the His-Pro bond

1990 ◽  
Vol 55 (4) ◽  
pp. 1106-1111 ◽  
Author(s):  
John Matsoukas ◽  
Paul Cordopatis ◽  
Raghav Yamdagni ◽  
Graham J. Moore
Keyword(s):  
1H Nmr ◽  
Nuclear Overhauser Effect ◽  
Nmr Studies ◽  
Restricted Rotation ◽  
Overhauser Effect ◽  
Major Isomer ◽  
Conformational Properties ◽  
Nuclear Overhauser

The conformational properties of the Sarmesin analogues [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in hexadeutero-dimethysulfoxide were investigated by Nuclear Overhauser Effect (NOE) Enhancement Studies. Cis-trans isomers (ratio 1 : 6) due to restricted rotation of the His-Pro bond were observed. Interresidue interactions between the His Cα proton and the two Pro Cδ protons revealed that the major isomer was the trans.

scholarly journals Cylindromicin from Arctic-Derived Fungus Tolypocladium sp. SCSIO 40433

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1080
Author(s):  
Imran Khan ◽  
Jing Peng ◽  
Zhuangjie Fang ◽  
Wei Liu ◽  
Wenjun Zhang ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Nuclear Overhauser Effect ◽  
Inhibition Activity ◽  
Tyrosinase Inhibition ◽  
Bioactive Natural Products ◽  
Chemical Structures ◽  
Overhauser Effect ◽  
Spectroscopic Analyses ◽  
Potential Resource ◽  
Nuclear Overhauser

The fungus strain SCSIO 40433 was isolated from an Arctic-derived glacier sediment sample and characterized as Tolypocladium cylindrosporum. A new compound, cylindromicin (1), and seven known secondary metabolites (2–8) were isolated from this strain. The chemical structures of these compounds were elucidated by comprehensive spectroscopic analyses. Cylindromicin (1) featured a 3,4-dihydro-2H-pyran skeleton. The absolute configuration of compound 1 was assigned via interpretation of key Nuclear Overhauser Effect Spectroscopy (NOESY) correlations and Electronic Circular Dichroism (ECD) calculation. Cylindromicin (1) exhibited significant tyrosinase inhibition activity. This study highlights Polar fungi as a potential resource for new bioactive natural products.

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