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.

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.

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.

A nuclear Overhauser effect difference study of the solution conformation of (6R)-prostaglandin I1

1980 ◽  
Vol 58 (23) ◽  
pp. 2649-2659 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts
Keyword(s):  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Solution Conformation ◽  
Magnetic Resonance Studies ◽  
Overhauser Effect ◽  
Complete Assignment ◽  
Effect Difference ◽  
Nuclear Overhauser

Proton magnetic resonance studies at 400 MHz allowed the complete assignment of the spectra for (6R)-prostaglandin I1 in phosphate buffer and in CDCl3 solutions. The spectral analysis was based on the nuclear Overhauser effect difference measurements, which also provide accurate chemical shifts and coupling constants. Conformational differences in the two solvents for the ring portion of the molecule are indicated.

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.

Proton magnetic resonance spectra of catechin and bromocatechin derivatives: C6- vs. C8-substitution

1986 ◽  
Vol 64 (10) ◽  
pp. 1998-2005 ◽  
Author(s):  
E. Kiehlmann ◽  
A. S. Tracey
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Overhauser Effect ◽  
Resonance Frequencies ◽  
The Difference ◽  
Nuclear Overhauser ◽  
Unambiguous Assignment ◽  
Magnetic Resonance Spectra

The 1Hmr spectra of 20 catechin derivatives substituted at C-6/C-8 by bromine and/or hydrogen and at oxygen by methyl, acetyl, and/or hydrogen have been analyzed in deuterated acetone, acetonitrile, and chloroform. Because of its dependence on the nature of the solvent and of the oxygen substituent, the difference between H-6 and H-8 chemical shifts has been found to be an unreliable criterion for the distinction between 8-bromo and 6-bromo isomers. In methylated catechins, double irradiation of H-8 and H-6 enhances one (MeO-7) and two (MeO-5 and MeO-7) methoxy signals, respectively, via the nuclear Overhauser effect. This permits unambiguous assignment of chemical shifts to all ring A protons. The H-6 and H-8 resonance frequencies of catechin have been determined by decoupling of the OH-5 and OH-7 protons.

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