Constituents of frontal gland secretion of peruvian termites Nasutitermes ephratae

1986 ◽  
Vol 51 (12) ◽  
pp. 2884-2895 ◽  
Author(s):  
Irena Valterová ◽  
Soňa Vašíčková ◽  
Miloš Buděšínský ◽  
Jan Vrkoč
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
Phenylacetic Acid ◽  
Volatile Fraction ◽  
Cd Spectra ◽  
Model Compounds ◽  
Frontal Gland ◽  
Defense Secretion ◽  
H Nmr ◽  
Work Up

The defense secretion of Nasutitermes ephratae soldiers was analyzed and its constituents were identified. The volatile fraction contains monoterpenic hydrocarbons α-pinene, camphene, sabinene, β-pinene, myrcene, 4-carene, 3-carene, α-terpinene, limonene, γ-terpinene, β-phellandrene, and terpinolene. From the non-volatile fraction four alcohols derived from trinervitane skeleton were isolated: 1(15),8(19)-trinervitadien-3α-ol (I), 1(15),8(19)-trinervitadien-2β,3α-diol (II) and its 2α,3α- (III) and 2α,3β- (IV) isomers. 3α-Hydroxy-1(15),8(19)-trinervitadien-2-one (V), which was also isolated, is probably an artefact formed during the work-up of the extract. The structure of 3β-hydroxy-1(15),8(19)-trinervitadien-2-one (VI) was determined on the basis of mass, IR and 1H NMR spectra, comparison with model compounds and analogy with the literature. The absolute configuration of the trinervitane skeleton was studied by CD spectra of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)praseodymium complexes of the 2,3-diols II-IV and by the 1H NMR spectra of esters of the alcohol I with (R)- and (S)-α-methoxy-α-(trifluoromethyl)phenylacetic acid. The results obtained by both methods are identical and confirm the earlier suggested absolute configuration of the trinervitane skeleton.

Preparation and absolute configuration at C(20) of 21-nor-5α-chol-22-en-24→20-olide derivatives

1981 ◽  
Vol 46 (4) ◽  
pp. 917-925 ◽  
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
Lithium Salt ◽  
H Nmr ◽  
Chemical Correlation ◽  
Unsaturated Lactones

Reaction of the aldehyde I with the lithium salt of 1-(2-tetrahydropyranyloxy)-2-propyne yielded the compounds II and IV. From the compound II the lactone XII was prepared via the intermediates III and X, the lactone XVIII was prepared from the substance IV via the intermediates V and XVI. The unsaturated lactones XII and XVIII were also prepared by sulfenylation and dehydrosulfenylation of the saturated lactones XIII and XIX. Based on chemical correlation and 1H-NMR spectra analyses of the compounds II and IV, the lactone XII was assigned the 20R-configuration whereas the lactone XVIII was allotted the 20S-configuration.

scholarly journals A New Bisabolene from Stevia tomentosa

2011 ◽  
Vol 6 (9) ◽  
pp. 1934578X1100600
Author(s):  
Alejandro Valdez-Calderón ◽  
J. Martín Torres-Valencia ◽  
J. Jesús Manríquez-Torres ◽  
René Velázquez-Jiménez ◽  
Mario A. Gómez-Hurtado ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Coupling Constants ◽  
Spectral Studies ◽  
Dihedral Angles ◽  
Model Compounds ◽  
H Nmr ◽  
Aerial Parts ◽  
The Absolute

The new sesquiterpene (1 R,2 R,3 R,6 R,7 S)-1-acetoxy-2,3-dmydroxy-2,3-dihydrobisabolene (3) together with ten known terpenes and three known flavonoids were isolated from the aerial parts and from the roots of Stevia tomentosa. The structure of 3 follows from spectral studies, the relative chirality at C-3 follows from 1H NMR coupling constants comparison with the corresponding calculated values obtained by applying a generalized Karplus-type relationship to the dihedral angles of model compounds, and the absolute configuration is assumed in analogy to known (2 R,3 R,6 R,7 S)-2,3-epoxy-2,3-dihydrobisabolen-1-one (2).

scholarly journals Antialactone: A New γ-Lactone from Antiaris Africana, and its Absolute Configuration Determined from TDDFT CD Calculations

2008 ◽  
Vol 3 (2) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Vouffo Bertin ◽  
Hidayat Hussain ◽  
Simeon F. Kouam ◽  
Etienne Dongo ◽  
Gennaro Pescitelli ◽  
...  
Keyword(s):  
Natural Product ◽  
Absolute Configuration ◽  
Betulinic Acid ◽  
Spectroscopic Data ◽  
Nmr Spectra ◽  
2D Nmr ◽  
Stem Bark ◽  
Cd Spectra ◽  
2D Nmr Spectra ◽  
First Time

Four compounds were isolated from the stem bark of Antiaris africana. One of them, a γ-lactone named antialactone (1a), is reported for the first time as a natural product. The structures were determined by comprehensive analyses of their 1D and 2D NMR spectra and EI MS data. The absolute configuration of antialactone acetate (1b) was established by TDDFT CD calculations and comparison with measured CD spectra. The remaining three known compounds were identified, by comparing their spectroscopic data with those reported in the literature, as lichenxanthone, β-sitosterol, and betulinic acid.

Defensive substances from the frontal gland secretion of Nasutitermes nigriceps termite soldiers

1991 ◽  
Vol 56 (12) ◽  
pp. 2969-2977 ◽  
Author(s):  
Irena Valterová ◽  
Miloš Buděšínský ◽  
Jan Vrkoč
Keyword(s):  
Detailed Analysis ◽  
Infrared Spectra ◽  
Nmr Spectra ◽  
Gland Secretion ◽  
Volatile Fraction ◽  
Termite Species ◽  
Frontal Gland ◽  
Derivatives Of ◽  
Termite Soldiers ◽  
C Nmr

The components of the defence secretion of the soldiers of Nasutiterms nigriceps termite species (Isoptera: Termitidae: Nasutitermitinae) have been identified. In the volatile fraction the following components were found: α- and β-pinene, camphene, myrcene, α-terpinene, p-cymene, limonene and terpinolene. Ten diterpenic compounds (I - X), mostly derivatives of the tricyclic trinervitane, were found in the non-volatile fraction. The structure of the so far undescribed 1(15),8(19)-trinervitadiene-2β,3α,14α-triol triacetate (X) was determined on the basis of its mass and infrared spectra and a detailed analysis of 1H and 13C NMR spectra. Considerable differences were found in the composition of the non-volatile fraction of the secretion of the species of termites studied from various localities.

Conformations of Chlorophylls a and a′ and their Magnesium-Free Derivatives as Revealed by Circular Dichroism and Proton Magnetic Resonance

1981 ◽  
Vol 36 (8) ◽  
pp. 1000-1009 ◽  
Author(s):  
Paavo H. Hynninen ◽  
Gunnel Sievers
Keyword(s):  
Circular Dichroism ◽  
Magnetic Resonance ◽  
Electronic Absorption ◽  
Proton Magnetic Resonance ◽  
Nmr Spectra ◽  
Cd Spectra ◽  
Steric Strain ◽  
Methyl Group ◽  
H Nmr ◽  
Circular Dichroïsm

Abstract The electronic absorption (UV/VIS), circular dichroism (CD) and proton magnetic resonance (1H NMR) spectra have been recorded for C-10 epimeric chlorophylls a and a′, pheophytins a and a′ as well as pheophorbides a and a′. Although the epimers in each pair showed virtually identical UV/VIS spectra, their CD spectra were profoundly different and exhibited opposite signs at most wavelengths in the UV region. The differences were interpreted as arising, in part, from different C-10 configurations, and, in part, from conformational alterations induced by the steric strain in the crowded periphery of the macrocycle. The conformational alterations were also clearly indicated by the 1H NMR Δδ-values observed for the α,β and δ methine protons, the C-10 protons and most methyl group protons of the epimers in each pair. This was considered to imply changes in the geometry of the whole macrocycle. The Δδ-values were larger for the Mg-free epimers than for the chlorophyll epimers, which shows that the central Mg-atom makes the macrocycle more rigid. Correlations between the signs of the CD bands and configurations are discussed.

9α-Hydroxyparthenolide from Zoegea baldschuanica C. WINKL. and its absolute configuration

1984 ◽  
Vol 49 (3) ◽  
pp. 637-641 ◽  
Author(s):  
Miloš Buděšínský ◽  
David Šaman ◽  
Gerard Nowak ◽  
Bohdan Drożdż ◽  
Miroslav Holub
Keyword(s):  
Absolute Configuration ◽  
Cd Spectra ◽  
H Nmr ◽  
Aerial Parts ◽  
Nmr Data

From the aerial parts of Zoegea baldschuanica C. WINKL. was isolated 9α-hydroxyparthenolide (I), whose absolute configuration was established on the basis of CD spectra. 1 H NMR data for I, parthenolide (VI) and the derivatives III and IV are discussed.

1H—NMR-spektroskopische Bestimmung der diastereomeren Reinheit und der absoluten Konfiguration am Phosphoratom von tButyl-phenyl-phosphinsäure-(—)-menthylester / Determination of the Diastereomeric Purity and the Absolute Configuration at Phosphorus of tButyl-phenyl-phosphinic Acid (—)-Menthyl Ester by Means of 1H NMR Spectroscopy

1977 ◽  
Vol 32 (5) ◽  
pp. 589-593 ◽  
Author(s):  
Reiner Luckenbach ◽  
Hans-H. Bechtolsheimer
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Absolute Configuration ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Phosphinic Acid ◽  
H Nmr ◽  
The Absolute ◽  
Diastereomeric Purity

The preparation and separation into diastereomers of tbutyl-phenyl-phosphinic acid (—)-menthyl ester (1a) is reported. The diastereomeric purity as well as the absolute configuration at phosphorus of 1 a can be deduced from the detailed analysis of the 1H NMR spectra of samples of 1a differing in their diastereomer ratios.

Synthesis and NMR Studies of Some Steroidal Isoxazoles

1992 ◽  
Vol 47 (6) ◽  
pp. 891-897 ◽  
Author(s):  
Sergio Giacopello ◽  
Mónica E. Deluca ◽  
Alicia M. Seldes
Keyword(s):  
Nmr Spectra ◽  
Two Dimensional ◽  
Model Compounds ◽  
Nmr Studies ◽  
Reaction Conditions ◽  
Related Model ◽  
H Nmr ◽  
Short Synthesis ◽  
Nmr Methods ◽  
C Nmr

A short synthesis of 17α-pregna-2,4-dien-[2,3-d]isoxazol-17β-ol (1) is described using mild reaction conditions and with a high overall yield. The equilibrium between keto-enolic forms has been studied by 1H NMR methods. Complete assignments of all the resonances in the 1H and 13C NMR spectra of Danazol have been made using a variety of one and two-dimensional correlation methods. 13C NMR spectra of all the intermediate and related model compounds were also assigned.

scholarly journals Determination of Absolute Stereochemistry of Natural Alicyclic Glycosides by 1H NMR Spectroscopy without Application of Chiral Reagents – An Indication

2011 ◽  
Vol 6 (5) ◽  
pp. 1934578X1100600 ◽  
Author(s):  
Tatyana N. Makarieva ◽  
Larisa K. Shubina ◽  
Alla G. Guzii ◽  
Natalya V. Ivanchina ◽  
Vladimir A. Denisenko ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Absolute Configuration ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
H Nmr ◽  
Steroid Glycosides ◽  
The Absolute ◽  
Absolute Stereochemistry

A study has been made of the 1H NMR spectra of peracetylated β-glucopyranosides and α-arabinopyranosides obtained by reaction of D- and L-glucoses, and L- and D-arabinoses with either ( R)- or ( S)-2-octanols. The obtained and literature data show that 1H NMR spectra may be used to determine the absolute configuration of the aglycone moieties of some alicyclic glycosides without the need to synthesize derivatives with chiral reagents, as long as the absolute configuration of their monosaccharide moiety is known or vice versa. Spectra of marine steroid glycosides and their acetates containing glycosylated side chains as alicyclic fragments were also examined. It was shown that analysis of 1H NMR spectra for the determination of the absolute configuration is more applicable in the cases when glycosides have the same substitution in the D-ring of the aglycone moiety.

Notizen: The Absolute Configuration of Julifloridine

1983 ◽  
Vol 38 (5) ◽  
pp. 660 ◽  
Author(s):  
Viqar Uddin Ahmad ◽  
Sabiha Qazi
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
H Nmr ◽  
The Absolute

Abstract The absolute configuration of julifloridine is proposed to be 2 R, 3 R, 6 R through 13C Spectra, 1H NMR Spectra,

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