Preparation and absolute configuration at C(22) of 21,26,27-trinor-5α-cholestan-25→22-olide derivatives

1985 ◽  
Vol 50 (4) ◽  
pp. 869-877 ◽  
Author(s):  
Vladimír Pouzar ◽  
Pavel Drašar ◽  
Ivan Černý ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Cd Spectra ◽  
Methyl Derivatives

Epimeric 21,26,27-trinor-5α-cholestan-25→22-olides (X and XVII), 21,26,27-trinor-5α-cholest-23-en-25→22-olides (XV and XXII), and their 23-methyl derivatives XVI and XXIII were prepared by lengthening the side chain in 5α-pregnan-21-al (I). On the basis of CD spectra and chemical correlations with 21,26,27-trinor-5α-cholestane-22,25-diols, the configuration 22S was ascribed to lactones X, XXII and XXIII whereas lactones XV, XVI and XVII were assigned the 22R configuration.

scholarly journals CD Spectra of 2,4-Dinitrophenyl Derivatives of α-Amino Acids Having Polynuclear Aromatic Group in the Side Chain. Absolute Configuration of 3-(9-Anthryl)alanine

1985 ◽  
Vol 58 (10) ◽  
pp. 3047-3048 ◽  
Author(s):  
Masao Kawai ◽  
Taketoshi Matsuura ◽  
Yasuo Butsugan ◽  
Syun Egusa ◽  
Masahiko Sisido ◽  
...  
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Side Chain ◽  
Cd Spectra ◽  
Aromatic Group ◽  
Derivatives Of

Absolute configuration at C(20) of the derivatives of 21-nor-5α-cholane-20,24-diol

1980 ◽  
Vol 45 (9) ◽  
pp. 2443-2451
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Chemical Correlation ◽  
The Absolute ◽  
Derivatives Of

Derivatives of 21-nor-5α-cholane-20,24-diol XI and XIX were prepared by stepwise construction of the side-chain in the position 17β. Their absolute configuration at C(20) was determined on the basis of chemical correlation with the derivatives of 21-nor-5α-cholan-20-ol, XVI and XXIV. The absolute configuration of alcohols XVI and XXIV was determined from the ratio of the yields in which they are formed during the reduction of ketone X and using the benzoate rule. To compounds XI-XVIII the configuration 20R and to compounds XIX-XXVI the configuration 20S has been assigned.

Conformation of ring A in 3-oxotriterpenoids. Dipole moments and CD spectra

1986 ◽  
Vol 51 (3) ◽  
pp. 611-620 ◽  
Author(s):  
Jiří Klinot ◽  
Václav Všetečka ◽  
Eva Klinotová ◽  
Alois Vystrčil
Keyword(s):  
Dipole Moments ◽  
Cd Spectra ◽  
Boat Form ◽  
Methyl Derivatives

The A ring of 3-oxotriterpenoids allobetulone (I) and 3-xo-lupane-28-nitrile (IV) exists by about 40% in the boat form as derived from comparison of their dipole moments with those of 2α-methyl derivatives II, V (chair models) and 2β-methyl compounds III, VI (boat models). The same result was obtained from the CD spectra of 3-oxotriterpenoids I-VIII and from isomerization of the 2α- and 2β-substituted ketones XI and XII, respectively.

Synthesis and conformation of sequential basic polypeptides with branched and linear side chains

1985 ◽  
Vol 50 (12) ◽  
pp. 2925-2936 ◽  
Author(s):  
Štěpánka Štokrová ◽  
Jan Pospíšek ◽  
Jaroslav Šponar ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Salt Concentration ◽  
Salt Solution ◽  
Theoretical Work ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Cd Spectra ◽  
Low Salt ◽  
Conformational Freedom ◽  
Basic Polypeptides

Polypeptides (Lys-X-Ala)n and (Lys-X-Gly)n in which X represents residues of isoleucine and norleucine, respectively, and polypeptide (Tle-Lys-Ala)n, were synthesized via polymerization of 1-hydroxysuccinimidyl esters of the appropriate tripeptides to complete previously studied series. Circular dichroism (CD) spectra of the respective polymers were measured as a function of pH and salt concentration of the medium. The results were correlated with those obtained previously with the same series containing different amino acid residues at the X-position. The helix forming ability of the polypeptides (Lys-X-Ala)n with linear X side chain was found to be independent of the length. In the series (Lys-X-Gly)n the unordered conformation was the most probable one except (Lys-Ile-Gly)n. This polymer assumed the β conformation even in low salt solution at neutral pH. An agreement with some theoretical work concerned with the restriction of conformational freedom of amino acid residue branching at Cβ atom with our experimental results is evident.

Preparation, spectral properties and biological activities of 5-bromo-6-methyl-2'-deoxyuridine and 5-iodo-6-methyl-2'-deoxyuridine

1980 ◽  
Vol 45 (8) ◽  
pp. 2364-2370 ◽  
Author(s):  
Antonín Holý ◽  
Erik De Clercq
Keyword(s):  
Antiviral Activity ◽  
Spectral Properties ◽  
De Novo ◽  
Biological Activities ◽  
Rabbit Kidney ◽  
Kidney Cells ◽  
Cd Spectra ◽  
Methyl Derivatives ◽  
Primary Rabbit

Reaction of 3',5'-di-O-benzoyl-6-methyl-2'-deoxyuridine (IIa) with elementary bromine or iodine afforded 5-halogeno derivatives IIc and IId which on methanolysis gave 5-bromo-6-methyl-2'-deoxyurine (Ic) and 5-iodo-6-methyl-2'-deoxyurine (Id), respectively. The CD spectra of Ic, Id and 6-methyl-2'-deoxyuridine (Ia) are compared and discussed with regard to determination of the nucleoside conformation. Unlike 5-bromo- and 5-iodo-2'-deoxyuridine, the 6-methyl derivatives Ic and Id exhibit neither antibacterial nor antiviral activity. Nor do they exert any antimetabolic effect on the de novo DNA synthesis in primary rabbit kidney cells.

scholarly journals Messung und Berechnung der CD-Spektren der Biaryl-Alkaloide Ancistrocladein und Dioncophyllein A [1] / Detection and Calculation of the CD Spectra from the Biaryl Alkaloids Ancistrocladeine and Dioncophylleine A [1]

1993 ◽  
Vol 48 (2) ◽  
pp. 140-148 ◽  
Author(s):  
J. Fleischhauer ◽  
A. Koslowski ◽  
B. Kramer ◽  
E. Zobel ◽  
G. Bringmann ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Cd Spectra ◽  
Circular Dichroïsm

AbstractThe circular dichroism (CD) of the biaryls ancistrocladeine and dioncophylleine A has been studied. The CNDO/S method in combination with a Boltzmann weighting o f different structures using AM 1 energies has been applied to reproduce the experimental CD spectra o f the two alkaloids with known absolute configuration at with those o f the exciton chirality method.

Juglomycins G-J: Isolation from Streptomycetes and Structure Elucidation

2005 ◽  
Vol 60 (2) ◽  
pp. 183-188 ◽  
Author(s):  
R. P. Maskey ◽  
H. Lessmann ◽  
S. Fotso ◽  
I. Grün-Wollny ◽  
H. Lackner ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Absolute Configuration ◽  
Structure Elucidation ◽  
Mass Spectra ◽  
2D Nmr ◽  
Cd Spectra ◽  
Streptomyces Spp ◽  
Nmr Data ◽  
Related Compounds ◽  
Weak Antibacterial Activity

From the Streptomyces spp. 815 and GW4184, four new 4-juglon-2-ylbutyric acid derivatives, the juglomycins G - J (3a, 4a, 4c, 5c), have been isolated and characterised. The structures were derived from the 1D and 2D NMR data and mass spectra and confirmed by comparison with structurally related compounds. The absolute configuration was deduced from the CD spectra. The new natural products exhibited weak antibacterial activity similar to juglomycin A (5a).

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