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

1981 ◽  
Vol 46 (1) ◽  
pp. 107-117 ◽  
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Acetic Acid ◽  
Absolute Configuration ◽  
Nmr Spectra ◽  
Lithium Salt ◽  
Diethyl Malonate ◽  
Methyl Propionate ◽  
H Nmr ◽  
Sodium Diethyl Malonate

The lactones X and XI were obtained on reaction of the aldehyde III with lithium salt of methyl propionate followed by hydrogenation of the intermediary esters IV and V. Treatment of the epoxides XXI and XXII with dilithium salt of acetic acid yielded the lactones X and XI. These lactones were also obtained by reaction of the epoxides XXI and XXII with sodium diethyl malonate through intermediates XXIII and XXV. The preparation of α-methylene lactones XXVII and XXVIII is also described. The 20R configuration was established for the lactones X, XXIII and XXVII while the lactones XI, XXV and XXVIII were assigned the 20S configuration both on the basis of 1H-NMR spectra and chemical correlations.

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 New Synthetic Routes for 1-Benzyl-1,4,7,10-tetraazacyclododecane and 1,4,7,10-Tetraazacyclododecane-1-acetic Acid Ethyl Ester, Important Starting Materials for Metal-coded DOTA-Based Affinity Tags

2007 ◽  
Vol 62 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Stephan W. Kohl ◽  
Katharina Kuse ◽  
Markus Hummert ◽  
Herbert Schumann ◽  
Clemens Mügge ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Ethyl Ester ◽  
Nmr Spectra ◽  
Acid Ethyl Ester ◽  
Affinity Tags ◽  
X Ray ◽  
H Nmr ◽  
Synthetic Routes ◽  
New Compounds ◽  
C Nmr

Two improved routes to synthesize 1-benzyl-1,4,7,10-tetraazacyclododecane (6) and 1,4,7,10- tetraazacyclododecane-1-acetic acid ethyl ester (11) are described as well as the synthesis of 1-{2-[4-(maleimido-N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane- 4,7,10-triacetic acid (17) and its Y, Ho, Tm, and Lu complexes. The 1H and 13C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of the intermediates 4-benzyl-1,7-bis(p-toluenesulfonyl)diethylenetriamine (3) and 1,4,7-tris(p-toluenesulfonyl)diethylenetriamine (7) are reported and discussed. The rare earth complexes of 17 have been characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry.

Preparation of 3-carboxypropanoates of digitoxin and digoxin and their conjugates with L-tyrosine

1985 ◽  
Vol 50 (12) ◽  
pp. 2760-2774 ◽  
Author(s):  
Pavel Drašar ◽  
Vladimír Pouzar ◽  
Ivan Černý ◽  
Miroslav Havel ◽  
František Tureček ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Methyl Ester ◽  
Nmr Spectra ◽  
Indirect Method ◽  
H Nmr ◽  
Coupling Reagent ◽  
Oxobutanoic Acid ◽  
C Nmr

Digitoxin and digoxin 4'''-(3-carboxypropanoates)(4'''-hemisuccinates) III and X were prepared by an indirect method, using dicyclohexylcarbodiimide-induced condensation of the cardioglycoside with 4-(2,2,2-trichloroethoxy)-4-oxobutanoic acid in dichloromethane in the presence of 4-dimethylaminopyridine or pyridine followed by removal of the 2,2,2-trichloroethyl group with zinc in a mixture of tetrahydrofuran, acetic acid and water. The hemisuccinates III and X were condensed with L-tyrosine methyl ester in tetrahydrofuran, using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline as the coupling reagent. Structure of the products was proved by 1H NMR and 13C NMR spectra. The conjugates IV and XI were labelled with [125I] in the L-tyrosine moiety. The obtained radioligands V and XII are designed as a part of the RIA system for cardioglycoside analyses.

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.

scholarly journals On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

2020 ◽  
Vol 16 ◽  
pp. 1863-1868
Author(s):  
Ilya V Taydakov ◽  
Mikhail A Kiskin
Keyword(s):  
Acetic Acid ◽  
Malonic Acid ◽  
Diethyl Malonate ◽  
Toxic Substances ◽  
New Approach ◽  
Preparative Yield ◽  
Benzyl Halides ◽  
Acidic Conditions ◽  
Hydrolysis Of ◽  
Sodium Diethyl Malonate

Diethyl 2-(perfluorophenyl)malonate was synthesized in 47% isolated yield by the reaction of sodium diethyl malonate and hexafluorobenzene. The resulting compound was considered as a starting material for synthesizing 2-(perfluorophenyl)malonic acid by hydrolysis. It was found that the desired 2-(perfluorophenyl)malonic acid could not be obtained from this ester by hydrolysis, neither under basic nor under acidic conditions. Nevertheless, hydrolysis of the ester with a mixture of HBr and AcOH gave 2-(perfluorophenyl)acetic acid in a good preparative yield of 63%. A significant advantage of this new approach to 2-(perfluorophenyl)acetic acid is that handling toxic substances such as cyanides and perfluorinated benzyl halides is avoided.

Schwefeldiimid, S(NH)2, und monosubstituierte Schwefeldiimide, S(NR)(NH), mit R = tert-Butyl und Trimethylsilyl / Sulfur Diimide, S(NH)2, and Monosubstituted Sulfur Diimides, S(NR)(NH), with R = tert-Butyl and Trimethylsilyl

1985 ◽  
Vol 40 (10) ◽  
pp. 1229-1232 ◽  
Author(s):  
Max Herberhold ◽  
Wolfgang Jellen ◽  
Wolfgang Bühlmeyer ◽  
Wolfgang Ehrenreich ◽  
Josef Reiner
Keyword(s):  
Acetic Acid ◽  
Nmr Spectra ◽  
Parent Compound ◽  
Temperature Dependent ◽  
Tert Butyl ◽  
H Nmr

The unstable parent compound of the sulfur diimides, S(NH)2 (1), has been obtained in solution by stoichiometric protonation of the anion SN22- in K2SN2 with acetic acid. An analogous protonation of the salts S(NR)(NK) leads to the m onosubstituted sulfur diimides S(NR)(NH) containing bulky substituents such as R = tert-butyl (2) and R = trimethylsilyl (3); 2 and 3 can be isolated as white solids below -40 °C. The temperature-dependent 1H NMR spectra of 1-3 indicate the presence of two isomers in solution (ratio 4:1) which are reversible interconverted.

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,

Optically active tricyclic dilactams with non-planar cis-amide groups: Synthesis, X-ray, NMR and CD studies

1982 ◽  
Vol 47 (3) ◽  
pp. 1000-1019 ◽  
Author(s):  
Karel Bláha ◽  
Miloš Buděšínský ◽  
Zdena Koblicová ◽  
Petr Maloň ◽  
Miloš Tichý ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
Condensation Reaction ◽  
Spatial Arrangement ◽  
Coupling Constants ◽  
X Ray Diffraction ◽  
Chiroptical Properties ◽  
X Ray ◽  
H Nmr ◽  
Cd Studies

Three tricyclic dilactams were investigated as models for study of chiroptical properties of homoconjugated non-planar cis-amide groups. Racemic 5,8-diazatricyclo[6,3,0,01,5]undecane-4,9-dione (I) was partially resolved into enantiomers by chromatography on acetylcellulose. The 6-isobutyl (II) and 6-methyl (III) derivatives were prepared in optically pure forms by condensation of diethyl 4-oxoheptanedioate with (S)-1,2-diamino-4-methylpentane and (S)-1,2-diamino-propane, respectively. The respective diamines were synthesized starting from (S)-leucine and (S)-alanine: this determined the absolute configuration on the C(6) atom in both dilactams. As shown by 1H and 13C NMR spectra, the condensation reaction afforded only one of the two possible diastereoisomeric dilactams. The configurational relation between the chiral center at C(6) and the chirality of the tricyclic moiety was derived from coupling constants in the 1H NMR spectra. The configuration of compound II was confirmed by X-ray diffraction. According to 1H NMR spectra, the spatial arrangement of II in solution is similar to that in crystal, the only difference being in the local conformation of the isobutyl side chain at C(6). IR spectroscopy identified only minor differences in geometry of the two lactam groupings in II and III. All CD parameters of compounds I-III, measured in various solvents, are very similar. The CD curves show the same absolute configuration (1S, 6S) of compounds II and III and the opposite configuration of the studied enantiomer of I(1R). Parameters of the n-π dichroic band indicate a non-planar amide-grouping whose geometry is known from the X-ray analysis. Its sign agrees with the relationship derived for the chiroptical properties of defined pyramidicity on nitrogen atom in non-planar amides. The π-π dichroic bands exhibit an exciton splitting into a couplet as a result of interaction between the amide groups.

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.

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