| | 1 | Author
| Bernd Wrackmeyer, Roland Köster, G. Ünter Seidel | Requires cookie* | | | Title
| Tricarbonyliron Complexes - Observation of 13C(CO) NMR Signals via Polarization Transfer  | | | | Abstract
| Improvements in the detection of 13C(CO) res onances by using polarization transfer techniques, based on long-range coupling constants "7(13C (C O)1H) = 1 ± 0.1 Hz (n > 3), are reported. Coupling constants between 13C(CO) and other rare spin-1/2 nuclei have been observed, and long-range 13C (C O)-'H coupling have been traced by two-dimensional (2 D) 13C/'H heteronuclear shift correlations (H ETC O R). Seven tricarbonyliron com plexes 1 to 5 serve as examples in which the [Fe(C O)3] fragment is linked to cyclic dienes (si-loles: la, b; l,l'-spirobisilole: 2), and to cyclic het erodienes derived from substituted | | | |
Reference
| Z. Naturforsch. 50b, 1127—1129 (1995); received November 17 1994 | | | |
Published
| 1995 | | | |
Keywords
| Tricarbonyliron Complexes, Cyclic Dienes, Cyclic Heterodienes, 13C NM R Spectra | | | |
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| default:Reihe_B/50/ZNB-1995-50b-1127_n.pdf | | | | Identifier
| ZNB-1995-50b-1127_n | | | | Volume
| 50 | |
| 2 | Author
| DavidS. Rycroft3, JosephD. Connolly3, SiegfriedH. Uneck, Uwe Himmelreich1 | Requires cookie* | | | Title
| Revised Structure of Haemoventosin | | | | Abstract
| The structure of the lichen pigm ent haem oventosin has been revised to 3,4,6,9-tetrahydro-5,10-dihydroxy-7-m ethoxy-3S-m ethyl-l,6,9-trioxo-l H-naphtho-[2,3-c]pyran (3), mainly on the basis of long-range <3C/<3H correlations observed in 2 D HM BC NMR experiments and long-range <5H/<5D isotope effects observed in partial deuteriation experiments with 10-0-acetylhaemoventosin; ortho-and /?öra-quinonoid structures were distinguished by means of the transacetylation inferred in the sodium dithionite reduction of lO-O-acetylhaemo-ventosin. | | | |
Reference
| Z. Naturforsch. 50b, 1557—1563 (1995); eingegangen am 13. März 1995 | | | |
Published
| 1995 | | | |
Keywords
| H aem oventosin, Naphthoquinone, O phioparm a ventosa, Lichen, 'H NMR Spectra, 13C NM R Spectra | | | |
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| default:Reihe_B/50/ZNB-1995-50b-1557.pdf | | | | Identifier
| ZNB-1995-50b-1557 | | | | Volume
| 50 | |
| 3 | Author
| A. Tta-, Ur-Rahm An, M. Bashir, S. Kaleem, T. Fatima, H.E J | Requires cookie* | | | Title
| Catharanthus roseus+ | | | | Abstract
| A new alkaloid has been isolated from the leaves o f Catharanthus roseus. Spectroscopic and degradative studies have established its structure to be 16-epi-19-S-vindolinine. In trod u ction While much work have been done on Catharan thus roseus (Apocynaceae) resulting in the isolation of about 100 alkaloids, there is persistent interest in the plant and new alkaloids continue to be reported. In continuation of our isolation and synthetic studies on the alkaloids of Catharanthus roseus [1 — 15], we have isolated a new alkaloid from the leaves of this plant by a combination of selective extraction, pre cipitation and crystallization and carried out spec troscopic and degradative studies on it to determ ine its structure. R esu lts and D iscu ssion | | | |
Reference
| Z. Naturforsch. 39b, 695—7 (1984); received N ovem ber 21 1983 | | | |
Published
| 1984 | | | |
Keywords
| Indoline A lkaloids, Catharanthus roseus, 13C NM R Spectra, V indolinine, Lead Tetraacetate | | | |
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| default:Reihe_B/39/ZNB-1984-39b-0695.pdf | | | | Identifier
| ZNB-1984-39b-0695 | | | | Volume
| 39 | |
| 4 | Author
| RichardM. Ynott, W. Olf, Jürgen Richter, G.Ünther Wilke | Requires cookie* | | | Title
| Determination of the Enantiomeric Excess of Horner Phosphines by 13C NMR Spectroscopy. A 13C and 31P NMR Study of the Diastereomeric Complexes Formed with [i/3-(+)(lR ,5R )-Pinenyl]nickel Bromide Dimer | | | | Abstract
| ohlenforschung, K aiser-W ilhelm -Platz 1, D-4330 M ülheim a. d. Ruhr, Federal Republic o f G erm any The 13C and 31P N M R data o f the H orner phosphines PRR'R" [R — M e. R' = f-Bu. R" = Ph (2) or /-Pr (4)] and their diastereom eric 1:1 adducts with [?73-(+) (l R .5R)-pinenyl]nickel bromide dimer (3) and (5), respectively, are reported. It is shown that the optical purities of the phosphines can be deduced easily from the N M R spectra. N ot only are these values in very good agreem ent with those obtained from optical rotatory data but they are also obtained much more con ve niently. | | | |
Reference
| (Z. Naturforsch. 41b, 85 [1986]; received A ugust 141985) | | | |
Published
| 1986 | | | |
Keywords
| Horner Phosphines, D eterm ination o f Optical Purity, 3IP NM R Spectra, 13C NM R Spectra | | | |
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| default:Reihe_B/41/ZNB-1986-41b-0085.pdf | | | | Identifier
| ZNB-1986-41b-0085 | | | | Volume
| 41 | |
| 5 | Author
| Bruno Perly, Patricia Le Bail-Richer, GiuseppeC. Pappalardo, Antonio Grassi | Requires cookie* | | | Title
| Molecular Determinants for Drug Receptor Interactions, 9 1H and 13C NMR Spectra of the Narcotic Antagonist N-Allyl-N-normetazocine by Two-Dimensional Chemical Shift Correlation Spectroscopy | | | | Abstract
| The high frequency 'H and l3C NM R spectra (at 500 and 75.47 M Hz, respectively) of N-allyl-N-norm etazocine (NAM) hydrochloride in :H 20 solution were run and fully analyzed with the aid of both homonuclear 'H —'H and heteronuclear 13C — 'H chemical shift correlation experiments. Selective broadening of the signals of the protons in 3-, 4-, 8-, 9-, 12-positions was observed at tem peratures < 350 K. This was found to be consistent with an inversion process occurring be tween the N -equatorial and N -axial configurational isomers of NAM whose rate of exchange is of the same order of magnitude of the chemical shifts differences at 500 MHz. The increase of tem perature at 350 K is thus adequate to make "fast" the process in the N M R time scale and then to resolve the spectral portions. The experim ental proton-proton coupling constants were found to be consistent with a slightly distorted chair conformation of the piperidinic ring in NAM hydrochloride. The 13C NM R spectrum showed the distinct spectra of the two conform ers, which are present in the ratio of ca. 80 (N -equatorial) : 20 (N -axial). The field frequency em ployed for the experim ent was therefore sufficient to make "slow" the exchange process betw een the two isomeric forms, whose resonance peaks could be isolated in the non-acidified solution. | | | |
Reference
| Z. Naturforsch. 42b, 1021 (1987); received D ecem ber 18 1986 | | | |
Published
| 1987 | | | |
Keywords
| Drug R eceptor, Interaction, 'H NM R Spectra, 13C NM R Spectra, Narcotic Antagonist | | | |
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| default:Reihe_B/42/ZNB-1987-42b-1021.pdf | | | | Identifier
| ZNB-1987-42b-1021 | | | | Volume
| 42 | |
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