The structure, stereochemistry, and biosynthetic origin of a diterpenoid fungal metabolite, traversianal, established by 1H, 2H, and 13C magnetic resonance

1988 ◽  
Vol 66 (5) ◽  
pp. 1084-1090 ◽  
Author(s):  
Albert Stoessl ◽  
G. L. Rock ◽  
J. B. Stothers ◽  
R. C. Zimmer
Keyword(s):  
Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Acetate Incorporation ◽  
Fungal Metabolite ◽  
Difference Spectra ◽  
Methyl Group ◽  
Heteronuclear Correlation ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser

The structure of traversianal, a tricyclic diterpenoid fungal metabolite of Cercospora traversiana, has been elucidated through detailed 1H and 13C magnetic resonance studies, including homo- and heteronuclear correlation spectra of the natural product and examination of 13C-labelled material obtained by [1,2-13C2]acetate incorporation experiments. Its stereochemistry was established from a series of nuclear Overhauser effect difference spectra. The tricyclic carbon skeleton of traversianal is that of the fusicoccin/cotylenin and ophiobolane terpenes although the oxygenation pattern closely resembles the latter. Incorporation experiments with [2,2,2-2H3, 1-13C1]acetate revealed that traversianal arises by a sequence that differs substantially from that established for the fusicoccanes but rather resembles that previously shown for the ophiobolanes, in the retention of hydride at C-2, -10, and -14. However, the opposite configuration of the methyl group at C-3 suggests that the route to traversianal involves a terminal trans-geranylgeranyl unit instead of the cis unit implicated in ophiobolin generation.

The isolation, structure, and stereochemistry of traversiadiene. The precursor hydrocarbon of traversianal biosynthesis

1989 ◽  
Vol 67 (8) ◽  
pp. 1302-1304 ◽  
Author(s):  
Albert Stoessl ◽  
G. L. Rock ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Biosynthetic Pathway ◽  
Nuclear Overhauser Effect ◽  
Difference Spectra ◽  
Heteronuclear Correlation ◽  
Magnetic Resonance Studies ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser ◽  
Magnetic Resonance Spectra

A tricyclic diene, traversiadiene, isolated from cultures of Cercosporatraversiana has been shown to have the structure and stereochemistry of the previously postulated hydrocarbon intermediate on the biosynthetic pathway to traversianal (1). Detailed:1H and 13C magnetic resonance studies, including homo- and heteronuclear correlation spectra, led to the gross structure, and the stereochemistry was established through a series of nuclear Overhauser effect difference spectra. Keywords: diterpene, traversiadiene, 1H and 13C magnetic resonance spectra.

A nuclear Overhauser effect difference study and a two-dimensional J proton magnetic resonance study of (6S)-prostaglandin I1

1981 ◽  
Vol 59 (10) ◽  
pp. 1449-1454 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts ◽  
Tom T. Nakashima
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Proton Resonances ◽  
Nuclear Overhauser

High-field nuclear Overhauser effect difference measurements allowed the assignment of the proton resonances for (6S)-prostaglandin I1 in phosphate buffer solutions. The two-dimensional J proton magnetic resonance experiments complemented these studies, as they also allowed the structure of several multiplets to be obtained when these multiplets are hidden by nearby resonances in a normal spectrum. The chemical shifts and coupling constants are compared with the data obtained previously for (6R)-prostaglandin I1.

Trijugins A and B, tetranortriterpenoids with a novel rearranged carbon skeleton from Heyneatrijuga (Meliaceae)

1987 ◽  
Vol 65 (1) ◽  
pp. 35-37 ◽  
Author(s):  
Kozhiparambil K. Purushothaman ◽  
Mathuram Venkatanarasimhan ◽  
Ayyappath Sarada ◽  
Joseph D. Connolly ◽  
David S. Rycroft
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Long Range ◽  
Nuclear Overhauser Effect ◽  
Carbon Skeleton ◽  
Overhauser Effect ◽  
Spectroscopic Examination ◽  
Effect Difference ◽  
Nuclear Overhauser ◽  
Derivatives Of

Two new tetranortriterpenoids, trijugins A (1) and B (3), isolated from the leaves of Heyneatrijuga (Meliaceae), have been shown to be derivatives of methyl angolensate but with a novel carbon skeleton having a contracted ring C. The structures were assigned on the basis of detailed 1H and 13C nuclear magnetic resonance spectroscopic examination including 2D long-range δC/δH correlation and homonuclear 1H nuclear Overhauser effect difference experiments.

Revised structure of a delta-aminolevulinic acid derivative

1993 ◽  
Vol 39 (9) ◽  
pp. 1867-1871 ◽  
Author(s):  
M Kajiwara ◽  
K Hara ◽  
K Takatori ◽  
K Matsumoto
Keyword(s):  
Aminolevulinic Acid ◽  
Nuclear Overhauser Effect ◽  
Correlation Spectroscopy ◽  
Molecular Formula ◽  
X Ray ◽  
Overhauser Effect ◽  
13C Nuclear Magnetic Resonance ◽  
Relative Arrangement ◽  
Effect Difference ◽  
Nuclear Overhauser

Abstract The structure of the fluorescent derivative formed in the method of Okayama et al. (Clin Chem 1990; 36:1494-7) for determining delta-aminolevulinic acid (ALA) concentrations was reinvestigated after esterification. The molecular ion peak at m/z 303.1473 corresponded to the molecular formula of C17H21NO4 (calcd 303.1470). The infrared spectrum showed the presence of carbonyl and carboxyl groups. This compound contained two acetyl groups, two methyl groups, and one methoxycarbonylethyl group, as revealed by 1H and 13C nuclear magnetic resonance and 13C-1H shift-correlated spectroscopy. Experiments with correlation spectroscopy via long-range coupling indicated that the main skeleton is 3H-pyrrolizine. The relative arrangement of functional groups was determined by means of nuclear Overhauser effect difference experiments. We were led to the conclusion that the methyl ester of the derivative is 2,6-diacetyl-1,5-dimethyl-7-(2-methoxycarbonylethyl)-3H-pyrrolizine. This structure was unequivocally confirmed by x-ray analysis; therefore, the structure of the derivative itself is 2,6-diacetyl-1,5-dimethyl-7-(2-carboxyethyl)-3H-pyrrolizine.

Cross-linked polydimethylsiloxane colloid as novel contrast agent for gastrointestinal magnetic resonance imaging: Transient nuclear Overhauser effect within the interface

2020 ◽  
Vol 35 (2) ◽  
pp. 264-273
Author(s):  
Fu-Hu Su ◽  
Wang-Chuan Xiao ◽  
Sheann-Huei Lin ◽  
Qiyong Li
Keyword(s):  
Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Relaxation Times ◽  
Resonance Imaging ◽  
Transverse Relaxation ◽  
Overhauser Effect ◽  
Nuclear Magnetic Resonance Spectra ◽  
Relaxation Experiments ◽  
Longitudinal Relaxation ◽  
Nuclear Overhauser

With good contrast in T1 and T2 weighted imaging as well as low toxicity in 3- (4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, this work proposes the cross-linked polydimethylsiloxane colloids as a novel non-ionic contrast agent for gastrointestinal magnetic resonance imaging. The experiments of nuclear magnetic resonance spectra and relaxation show that within the interface of the colloids, there are nuclear Overhauser effect and transient nuclear Overhauser effect (cross-relaxation). Regarding the longitudinal relaxation experiments of CH2CH2O segments of Tween 80, a two spins system is found and modeled well by the equation [Formula: see text] which is deduced based on the transient nuclear Overhauser effect proposed by Solomon. The arbitrary constant X is additionally added with the initial conditions ( Iz −  I0) t=0 = −2 XS0 and ( Sz −  S0) t=0 = −2 S0. For the two spins system, D1 and T1 are corresponding to longitudinal relaxation times of the bound water and the CH2CH2O respectively. Concerning the transverse relaxation experiments of the CH2CH2O, they agree with the equation with three exponential decays, defined by three relaxation times, likely corresponding to three mechanisms. These mechanisms possibly are intramolecular and intermolecular dipole–dipole (DD) interactions and scalar coupling. Within the interface, hydrogen bonding causes the positive nuclear Overhauser effect of the CH2CH2O’s nuclear magnetic resonance spectra, the transient nuclear Overhauser effect of the CH2CH2O’s longitudinal relaxation experiments and the intermolecular dipole–dipole interactions of the CH2CH2O’s transverse relaxation experiments.

Coprinolone and Δ6-coprinolone: new sesquiterpenes from Coprinus psychromorbidus

1989 ◽  
Vol 67 (3) ◽  
pp. 417-427 ◽  
Author(s):  
Alvin N. Starratt ◽  
Edmund W. B. Ward ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Chemical Transformations ◽  
Difference Spectra ◽  
Heteronuclear Correlation ◽  
Magnetic Resonance Studies ◽  
Nuclear Overhauser

The structure of coprinolone (1), an oxygen-bridged protoilludane from the W2 isolate of the fungus Coprinuspsychromorbidus, has been elucidated by chemical transformations and detailed 1H and 13C magnetic resonance studies, including homo- and heteronuclear correlation spectra. The 1H–1H coupling data and nuclear Overhauser difference spectra for 1 and derived isomers led to the establishment of its stereochemistry. A second metabolite was identified as Δ6-coprinolone (20) by spectroscopic results. Confirmatory evidence in support of the structures was obtained from the labelling patterns of the compounds from cultures supplemented with sodium [1,2-13C2]acetate. Keywords: coprinolone, Δ6-coprinolone, protoilludane, sesquiterpenes, NMR.

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