Caerulomycin D, a novel glycosidic derivative of 3,4-dihydroxy-2,2′-dipyridyl 6-aldoxime from Streptomyces caeruleus

1978 ◽  
Vol 56 (13) ◽  
pp. 1836-1842 ◽  
Author(s):  
A. Gavin McInnes ◽  
Donald G. Smith ◽  
John A. Walter ◽  
Jeffrey L. C. Wright ◽  
Leo C. Vining ◽  
...  
Keyword(s):  
Ring System ◽  
Nmr Spectrometry ◽  
C Nmr

Analysis by 1H and 13C nmr spectrometry showed that caerulomycin D, a new metabolite isolated from S. caeruleus, possessed a novel ring system and had the structure (2S,3R,4R,4aS,10aS)-3,4,4a,10a-tetrahydro-4-hydroxy-3,4a-diniethoxy-2-methyl-9-(2-pyridyl)-2H-pyrano[3′,2′:5,6]-p-dioxino[2,3-c]pyridine-7-carboxaldenyde (E)-oxime.

Identification of substituted furyltetrazolyl acetates by means of 13C NMR spectrometry

1984 ◽  
Vol 49 (8) ◽  
pp. 1895-1899 ◽  
Author(s):  
Jan Světlík ◽  
Igor Goljer ◽  
Ľubomír Janda
Keyword(s):  
Chemical Shift ◽  
13C Nmr ◽  
Ring System ◽  
Tetrazole Ring ◽  
Nmr Data ◽  
Nmr Spectrometry ◽  
C Nmr

13C NMR data of a series of 5-[5-(substituted phenyl)-2-furyl]-1- and -2-tetrazolyl acetates are presented. Examination of diagnostic resonances emphasizing particularly those arising from the tetrazole ring system enabled both isomers to be easily distinguished. The chemical shift increment for 5-(2-furyl)-1- and -2-tetrazolyl acetate unit has been deduced.

Ease of delignification assessment of wood from different Eucalyptus species by pyrolysis (TMAH)-GC/MS and CP/MAS 13 C-NMR spectrometry

1999 ◽  
Vol 49 (1-2) ◽  
pp. 295-305 ◽  
Author(s):  
F.J González-Vila ◽  
G Almendros ◽  
J.C del Rio ◽  
F Martı́n ◽  
A Gutiérrez ◽  
...  
Keyword(s):  
Eucalyptus Species ◽  
Nmr Spectrometry ◽  
C Nmr

Untersuchungen zur Ringkontraktion am 1,4-Dithia-2,6-diaza-3,5-diborinan-System/ Studies on Ring Contraction of the l,4-Dithia-2,6-diaza-3,5-diborinane System

1988 ◽  
Vol 43 (8) ◽  
pp. 959-962 ◽  
Author(s):  
Carl Habben ◽  
Anton Meiler ◽  
Stefan Pusch
Keyword(s):  
Mass Spectra ◽  
Ring System ◽  
Membered Ring ◽  
Ring Contraction ◽  
C Nmr

AbstractThe 1,4-dithia-2,6-diaza-3,5-diborinanes 1a-d react with elemental sodium with formation of the 1,3-diaza-2,4-diboretidines 2a-d. By use of more sodium in case of 1 d or 3,5-bis(diethylamino)- 2-cyclohexyl-6-trimethylsilyldiborinane, the 1,3-thiaza-2,4-diboretidines 3 were formed. 3.5-Dimethyl-2,6-bis(trimethylsilyl)-1,4-dithia-2,6-diaza-3,5-diborinane gives the borazine 4, The reaction of di-t-butyl-sulfurdiimide with 2,6-di-t-butyl-3,5-dimethyl-1,4-dithia-2,6-diaza-3,5-diborinane leads by ring contraction to the four-membered ring system 5. 1H, 11B, 13C NMR and mass spectra are reported and discussed.

Zur Struktur des Enols von Benzoylaceton / On the Structure of the Enol of Benzoylacetone

1979 ◽  
Vol 34 (11) ◽  
pp. 1606-1611 ◽  
Author(s):  
W. Winter ◽  
K.-P. Zeller ◽  
S. Berger
Keyword(s):  
Structural Model ◽  
Chemical Shifts ◽  
Ring System ◽  
Coupling Constants ◽  
Spin Coupling ◽  
X Ray ◽  
Wide Range ◽  
Spin Coupling Constants ◽  
C Nmr ◽  
Oxygen Atoms

Abstract A low temperature X-ray study of the enol of benzoylacetone indicates fixed positions of the C and O atoms within the enolic ring system and an extensive bond delocalisation over these atoms. The distribution of electron density between the two oxygen atoms shows that the enolic hydrogen is spread over a wide range. This is in accordance with a structural model proposed by de la Vega, whereupon the C and O atoms are kept fixed in their average positions during a tunneling process of the hydrogen between the two oxygen atoms. With this conception, the chemical shifts in the 17O and 13C NMR spectra, the 13C13C spin coupling constants and the temperature independance of these values can be explained.

Oxidation of triamantane by sulphuric acid

1983 ◽  
Vol 48 (4) ◽  
pp. 1074-1076 ◽  
Author(s):  
Zdeněk Kafka ◽  
Luděk Vodička ◽  
Milan Hájek
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Sulphuric Acid ◽  
Functional Groups ◽  
Reaction Products ◽  
Reaction Conditions ◽  
Nmr Spectrometry ◽  
C Nmr

The oxidation of triamantane by sulphuric acid was studied in various reaction conditions. 8-Triamantanone, 8,16-triamantanedione, and 15-hydroxy-8-triamantanone were isolated and identified as reaction products. The reaction was monitored and the purity of the compounds prepared was checked by gas chromatography and mass spectrometry, the position of the functional groups was determined by 13C NMR spectrometry.

scholarly journals A Facile and Catalyst-free Synthesis of Hexahydroacridine-1,8(2H,5H )-dione and Octahydroacridin-10(1H )-yl)thiourea Derivatives: Inter- and Intramolecular Aza-Michael addition

2020 ◽  
Vol 26 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Nader Noroozi Pesyan ◽  
Narmin Akhteh ◽  
Hana Batmani ◽  
Barış Anıl ◽  
Ertan Şahin
Keyword(s):  
Hydroxylamine Hydrochloride ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
One Pot ◽  
Thiourea Derivatives ◽  
H Nmr ◽  
Nmr Spectrometry ◽  
The One ◽  
Convenient Technique ◽  
C Nmr

AbstractAn easy and convenient technique for the one-pot synthesis of novel compounds of hexahydroacridine-1,8(2H,5H)-dione and octahydroacridin-10(1H)-yl) thiourea derivatives has been developed by the reaction of the octahydro-1H-xanthenes with hydroxylamine hydrochloride and thiosemicarbazide in ethylene glycol, which is a green solvent, under mild reaction conditions. IR, 1H NMR, 13C NMR spectrometry, and X-ray diffraction analysis were used to identify the structures of these compounds.

Conformational analysis of the bicyclo - [4.4.1]undecan-11-one ring system

2002 ◽  
Vol 80 (3) ◽  
pp. 245-249
Author(s):  
Masood Parvez ◽  
Ted S Sorensen ◽  
Fang Sun
Keyword(s):  
Conformational Analysis ◽  
Symmetry Plane ◽  
Ring System ◽  
Line Broadening ◽  
X Ray ◽  
The One ◽  
Effective Development ◽  
System 1 ◽  
C Nmr ◽  
Dibromo Derivative

The first conformational analysis of a bicyclo[4.4.1]undecan-11-one system (1) is presented. Based on low-temperature 13C NMR line-broadening measurements and an X-ray structure of the 1,6-dibromo derivative (2), this ketone adopts a chiral conformation with approximate C2 symmetry about an axis containing the >C=0 bond. The observed NMR line-broadening results are consistent with a dynamic interchange of M and P enantiomeric C2 conformations, or expressed another way, the "effective" development of an additional Cs symmetry plane bisecting the molecule at right angles to the plane containing the one carbon bridge (overall average C2v symmetry). This process has a ΔH‡ barrier of 42 kJ mol–1 for ketone 1 (43 kJ mol–1 for 2).Key words: bicyclo[4.4.1]undecan-11-one, conformational analysis, NMR line broadening, X-ray structure, enantiomers.

scholarly journals A retro-biosynthetic approach to the prediction of biosynthetic pathways from position-specific isotope analysis as shown for tramadol

2015 ◽  
Vol 112 (27) ◽  
pp. 8296-8301 ◽  
Author(s):  
Katarzyna M. Romek ◽  
Pierrick Nun ◽  
Gérald S. Remaud ◽  
Virginie Silvestre ◽  
Germain Sotoing Taïwe ◽  
...  
Keyword(s):  
Positional Distribution ◽  
Isotope Analysis ◽  
Natural Abundance ◽  
Medicinal Tree ◽  
Specific Distribution ◽  
Novel Approach ◽  
Nmr Spectrometry ◽  
Recent Developments ◽  
Better Than ◽  
C Nmr

Tramadol, previously only known as a synthetic analgesic, has now been found in the bark and wood of roots of the African medicinal tree Nauclea latifolia. At present, no direct evidence is available as to the biosynthetic pathway of its unusual skeleton. To provide guidance as to possible biosynthetic precursors, we have adopted a novel approach of retro-biosynthesis based on the position-specific distribution of isotopes in the extracted compound. Relatively recent developments in isotope ratio monitoring by 13C NMR spectrometry make possible the measurement of the nonstatistical position-specific natural abundance distribution of 13C (δ13Ci) within the molecule with better than 1‰ precision. Very substantial variation in the 13C positional distribution is found: between δ13Ci = −11 and −53‰. Distribution is not random and it is argued that the pattern observed can substantially be interpreted in relation to known causes of isotope fractionation in natural products. Thus, a plausible biosynthetic scheme based on sound biosynthetic principals of precursor–substrate relationships can be proposed. In addition, data obtained from the 18O/16O ratios in the oxygen atoms of the compound add support to the deductions made from the carbon isotope analysis. This paper shows how the use of 13C NMR at natural abundance can help with proposing a biosynthetic route to compounds newly found in nature or those difficult to tackle by conventional means.

scholarly journals Jasomontanone, a Novel Bicyclic Sesquiterpene from the Leaves of Jasonia montana

2006 ◽  
Vol 1 (1) ◽  
pp. 1934578X0600100 ◽  
Author(s):  
Ahmed A. Mahmoud
Keyword(s):  
Chemical Transformation ◽  
Spectroscopic Data ◽  
2D Nmr ◽  
Ring System ◽  
C Nmr

A novel rearranged eudesmane sesquiterpene with a new 5/7 membered bicyclic-ring-system, jasomontanone, was isolated from Jasonia montana. Its structure was determined as (3a R*, 6 R*, 8a R)-3a-(hydroxymethyl)-6-(2-hydroxy-propan-2-yl)-8a-methyl-octahydrazulen-4(5 H)-one by analysis of spectroscopic data (IR, HR-MS, 1H and 13C NMR), including 2D NMR (1H-1H COSY, HMQC, HMBC and NOESY), chemical transformation, and biogenetic consideration.

Die Kooperativität bei der CO2-Hb-Bindung: Messungen mit Hilfe der 13C-NMR-Spektrometrie / The Cooperativity of the CO2 Hb Binding: Measurement by 13C -NMR Spectrometry

1979 ◽  
Vol 34 (12) ◽  
pp. 1112-1120
Author(s):  
O. Burkhard ◽  
W. K. R. Barnikol
Keyword(s):  
Quantitative Analysis ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Internal Standard ◽  
Detailed Structure ◽  
Physiological Conditions ◽  
Nmr Spectrometry ◽  
Binding Curve ◽  
Haldane Effect ◽  
C Nmr

The detailed structure of the CO2 Hb binding curve is of considerable physiological interest, because the carbamino derivates, which are formed by the reaction of CO2 with Hb, are respon­sible for the well known Haldane effect. Under physiological conditions CO2 binds to the four terminal NH2-groups of the protein chains of Hb and it is generally assumed, that there exists no cooperativity between these groups. To examine whether this assumption is correct or not, we have measured the CO2Hb binding curve over a wide PCO2-range (from 0 kPa to about 70 kPa) by using 13C-NMR spectrometry. Morrow and coworkers (1976) have shown that carbamino-Hb causes a specific NMR signal. The quantitative analysis of the NMR spectra were done according to the method of internal standard. By analyzing mixtures of known composition, we were able to show that this method is working. So we had to use the following equation: Z is the CO2 saturation of Hb, I is the intensity of the carbamino signal, and IHb is the intensity of the carbons of Hb, which are involved in the amide binding. (I/IHb)max is (I/IHb) at high PCO2, where Hb is completely saturated by CO2. For our experiments we used solutions of human desoxygenated Hb, which were equilibrated with a mixture of N2 and CO2. The CO2 contained 90% 13C-isotope. The pH was adjusted by titration to 7.2. The NMR measurements were mainly done with a Varian XL 100 NMR spec­trometer. The CO2 Hb binding curve, we have measured, is S-shaped and has an average Hill value (n̅) of 2.1. This result is quite striking with respect to the findings of other groups. A Hill value of 2.1 proves that CO2 like O2 binds to Hb in a cooperative manner. The discrepancy to the results of other groups may be explained by the fact that these authors measured the CO2 Hb binding curve only at comparatively low PCO2. In our opinion one can only get reliable n-values from the whole CO2 Hb binding curve.

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