The Allylic Rearrangement of the Hydroxyl Group from C-9 to C-13 and the Absolute Configuration at C-9 of Leucomycin A3

1968 ◽  
Vol 16 (7) ◽  
pp. 1402-1404 ◽  
Author(s):  
SATOSHI OMURA ◽  
MICHIKO KATAGIRI ◽  
TOJU HATA ◽  
MIKIO HIRAMATSU ◽  
TERUTOSHI KIMURA ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Hydroxyl Group ◽  
Allylic Rearrangement ◽  
The Absolute

Absolute stereochemistry of the spiroxins

2001 ◽  
Vol 79 (11) ◽  
pp. 1786-1791 ◽  
Author(s):  
Tao Wang ◽  
Osamu Shirota ◽  
Koji Nakanishi ◽  
Nina Berova ◽  
Leonard A McDonald ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Group ◽  
Exciton Coupling ◽  
The Absolute ◽  
The Difference ◽  
Circular Dichroïsm ◽  
Absolute Stereochemistry

The absolute configuration of spiroxin A has been determined by exciton-coupled circular dichroism (CD). Namely, the difference CD between spiroxin A – bis-methoxycinnamate, as well as that between spiroxin A – bis-retinoate, both exhibit negative exciton couplings between the acylated phenolic hydroxyl group chromophores. This establishes the absolute configuration as 2S,3R,4S,2'S,3'R,4'S.Key words: circular dichroism, exciton coupling, spiroxins, antitumor, antifungal.

scholarly journals The altered specificity of cortisone reductase with certain retroandrostan-3-one substrates

1975 ◽  
Vol 145 (3) ◽  
pp. 483-489 ◽  
Author(s):  
W Gibb ◽  
J Jeffery ◽  
David N. Kirk ◽  
H Mahdi
Keyword(s):  
Absolute Configuration ◽  
Substrate Recognition ◽  
Hydroxyl Group ◽  
Appreciable Amount ◽  
Hydroxy Compound ◽  
Structure Activity Relationships ◽  
Good Substrate ◽  
Structure Activity ◽  
The Absolute ◽  
Hydroxy Compounds

The retro steroids 17beta-hydroxy-5beta,9beta,10alpha-androstan-3-one and 5beta,9beta,10alpha-androstane-3,17-dione were good substrates for cortisone reductase in the presence of NADH, and the products corresponded to the respective 3beta-hydroxy compounds, in which the 3beta-hydroxyl group is axial and the absolute configuration is 3S. The analogous natural steroids 17beta-hydroxy-5beta,9alpha,10beta-androstan-3-one and 5beta,9alpha,10beta-androstane-3,17-dione were very poor substrates, and gave the corresponding 3alpha(equatorial,3R)-hydroxy compounds, and, in the latter case, also an appreciable amount of 3beta(axial, 3S)-hydroxy-5beta,9alpha,10beta-androstan-17-one. The natural steroids 17beta-hydroxy-5alpha,9alpha,10beta-androstan-3-one and 5alpha,9alpha,10beta-androstane-3,17-dione were better substrates than the retro steroid 17beta-hydroxy-5alpha,9beta,10alpha-androstan-3-one, but were not such good substrates as the retro steroids 17beta-hydroxy-5beta,9beta,10alpha-androstan-3-one and 5beta,9beta,10alpha-androstane-3,17-dione. Unlike these retro steroid 5beta,9beta,10alpha-androstan-3-ones, the natural steroids 17beta-hydroxy-5alpha,9alpha,10beta-androstan-3-one and 5alpha,9alpha,10beta-androstane-3,17-dione gave the corresponding 3alpha(axial,3R)-hydroxy compounds. The retro steroid 17beta-hydroxy-5alpha,9beta,10alpha-androstan-3-one was not a good substrate, and the product of reaction corresponded to the 3alpha(axial,3R)-hydroxy compound. The nature of substrate recognition by this enzyme is discussed in the light of these structure-activity relationships.

Evaluation of Different Synthetic Routes to (2R,3R)-3-Hydroxymethyl-2-(4-hydroxy- 3-methoxyphenyl)-1,4-Benzodioxane-6-Carbaldehyde

2020 ◽  
Vol 23 (26) ◽  
pp. 2960-2968
Author(s):  
Renáta Kertiné Ferenczi ◽  
Tünde-Zita Illyés ◽  
Sándor Balázs Király ◽  
Gyula Hoffka ◽  
László Szilágyi ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Stereoselective Synthesis ◽  
Cotton Effect ◽  
Enantioselective Synthesis ◽  
Aryl Group ◽  
Target Molecule ◽  
Synthetic Routes ◽  
The Absolute

The reported enantioselective synthesis for the preparation of (+)-(2R,3R)-2-(4- hydroxy-3-methoxyphenyl)-3-hydroxymethyl-1,4-benzodioxane-6-carbaldehyde, precursor for the stereoselective synthesis of bioactive flavanolignans, could not be reproduced. Thus, the target molecule was prepared via the synthesis and separation of diastereomeric O-glucosides. TDDFT-ECD calculations and the 1,4-benzodioxane helicity rule were utilized to determine the absolute configuration. ECD calculations also confirmed that the 1Lb Cotton effect is governed by the helicity of the heteroring, while the higher-energy ECD transitions reflect mainly the orientation of the equatorial C-2 aryl group.

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.

Absolute Stereochemistry of (-)-Wieland-Miescher Ketone as Established by the X-ray Crystallographic and CD Exciton Chirality Methods

1992 ◽  
Vol 57 (7) ◽  
pp. 1459-1465 ◽  
Author(s):  
Nobuyuki Harada ◽  
Tatsuo Sugioka ◽  
Hisashi Uda ◽  
Takeo Kuriki
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The 8aR absolute stereochemistry of Wieland-Miescher ketone (-)-I was established by the X-ray structure analysis of its bis(4-bromobenzoate) derivatives (1R,6R,8aR)-(+)-IV and (1R,6S,8aR)-(-)-V. The absolute configuration of (-)-I was corroborated further by the application of the CD exciton chirality method to bis(4-bromobenzoates) (+)-IV and (-)-V.

scholarly journals Rapid Organocatalytic Chirality Analysis of Amines, Amino Acids, Alcohols, Amino Alcohols and Diols with Achiral Iso(thio)cyanate Probes

2021 ◽  
Author(s):  
Eryn Nelson ◽  
Jeffrey S. S. K. Formen ◽  
Christian Wolf
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Rapid Determination ◽  
Amino Alcohols ◽  
Enantioselective Synthesis ◽  
Widespread Occurrence ◽  
Chiral Compounds ◽  
New Methods ◽  
The Absolute

The widespread occurrence and significance of chiral compounds does not only require new methods for their enantioselective synthesis but also efficient tools that allow rapid determination of the absolute configuration,...

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

scholarly journals Massiliamide, a cyclic tetrapeptide with potent tyrosinase inhibitory properties from the Gram-negative bacterium Massilia albidiflava DSM 17472T

2020 ◽  
Author(s):  
Andri Frediansyah ◽  
Jan Straetener ◽  
Heike Brötz-Oesterhelt ◽  
Harald Gross
Keyword(s):  
Absolute Configuration ◽  
Inhibitory Activity ◽  
Liquid Culture ◽  
Spectroscopic Analysis ◽  
2D Nmr ◽  
Negative Bacterium ◽  
Gram Negative ◽  
The Absolute ◽  
Potent Inhibitory Activity ◽  
Cyclic Tetrapeptide

AbstractA cyclic tetrapeptide, designated massiliamide, was isolated from the liquid culture of the Gram-negative bacterium Massilia albidiflava DSM 17472T. The structure was elucidated through extensive spectroscopic analysis, including HR-MS and 1D and 2D NMR experiments. The absolute configuration was determined using the Marfey´s method. Massiliamide showed potent inhibitory activity towards tyrosinase with an IC50 value of 1.15 µM and no cytotoxicity.

Sign in / Sign up

Export Citation Format

Share Document