scholarly journals Expanding the Repertoire of Spongian-16-One Derivatives in Australian Nudibranchs of the Genus Goniobranchus and Evaluation of Their Anatomical Distribution

Marine Drugs ◽  
2021 ◽  
Vol 19 (12) ◽  
pp. 680
Author(s):  
Louise C. Forster ◽  
Jack K. Clegg ◽  
Karen L. Cheney ◽  
Mary J. Garson
Keyword(s):  
Absolute Configuration ◽  
Animal Tissue ◽  
Mantle Tissue ◽  
Relative Configuration ◽  
Anatomical Distribution ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute

Extracts of the mantle and viscera of the Indo-Pacific nudibranchs Goniobranchus aureopurpureus and Goniobranchus sp. 1 afforded 11 new diterpenoids (1–11), all of which possess a tetracyclic spongian-16-one scaffold with extensive oxidation at C-6, C-7, C-11, C-12, C-13, and/or C-20. The structures and relative configuration were investigated by NMR experiments, while X-ray crystallography provided the absolute configuration of 1, including a 2′S configuration for the 2-methylbutanoate substituent located at C-7. Dissection of animal tissue revealed that the mantle and viscera tissues differed in their metabolite composition with diterpenes 1–11 present in the mantle tissue of the two nudibranch species.

The synergy of different solid-state techniques to elucidate the supramolecular assembly of two 1H-benzotriazole polymorphs

2019 ◽  
Vol 21 (36) ◽  
pp. 19879-19889
Author(s):  
María Mar Quesada-Moreno ◽  
Juan Ramón Avilés-Moreno ◽  
Juan Jesús López-González ◽  
Fco. Javier Zúñiga ◽  
Dolores Santa María ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Chemical Calculations ◽  
Absolute Configuration ◽  
Quantum Chemical ◽  
Supramolecular Structure ◽  
Supramolecular Assembly ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute

4aα (chiral) and 4aβ (achiral) polymorphs of 1H-benzotriazole are studied by X-ray crystallography, SSNMR, IR, Raman, VCD, and quantum chemical calculations. The absolute configuration of the supramolecular structure of 4aα polymorph is determined.

scholarly journals 2,4-Dimethyl-3,4-O-isopropylidene-L-arabinono-1,5-lactone

2007 ◽  
Vol 63 (3) ◽  
pp. o1128-o1130 ◽  
Author(s):  
Kathrine V. Booth ◽  
David J. Watkin ◽  
Sarah F. Jenkinson ◽  
George W. J. Fleet
Keyword(s):  
Absolute Configuration ◽  
Crystallographic Analysis ◽  
Starting Material ◽  
Relative Configuration ◽  
X Ray ◽  
Boat Form ◽  
The Absolute

The relative configuration at C-2 of 2,4-dimethyl-3,4-O-isopropylidene-L-arabinono lactone, C10H16O5, which exists in the boat form, was unequivocally established by X-ray crystallographic analysis. The absolute configuration was determined by the use of 2-C-methyl-D-ribonolactone as a starting material.

Conclusive Determination of the Absolute Configuration of Chiral C60-Fullerenecis-3 Bisadducts by X-ray Crystallography and Circular Dichroism

2005 ◽  
Vol 117 (15) ◽  
pp. 2302-2305 ◽  
Author(s):  
Shunsuke Kuwahara ◽  
Kazuhiro Obata ◽  
Kazuhiro Yoshida ◽  
Takatoshi Matsumoto ◽  
Nobuyuki Harada ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute ◽  
Circular Dichroïsm

Structures and Synthesis of 4a-Homo-7,19-dinorsteroids, X-Ray Crystallography and NMR Spectroscopy

1999 ◽  
Vol 64 (12) ◽  
pp. 2019-2034 ◽  
Author(s):  
Alexander Kasal ◽  
Miloš Buděšínský ◽  
Jan Pelnař ◽  
Michael A. Bruck ◽  
Michael F. Brown
Keyword(s):  
Nmr Spectroscopy ◽  
Absolute Configuration ◽  
Starting Material ◽  
Nmr Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Crystallography ◽  
Leaving Group ◽  
The Absolute ◽  
Related Compounds

X-Ray diffraction revealed the absolute configuration of 4aβ-methyl-4a-homo-7,19-dinor- 5α,10α-androstane-3,17-dione. Detailed NMR analysis suggested that the 5α configuration existed in the starting material, 3β-acetoxy-4a-methylidene-4a-homo-7,19-dinor- 5α-androst-9-en-17-one, and related compounds. Thus 5-methyl-5β-estr-9-ene derivatives with a leaving group in position 6β were found to react with nucleophiles to form rearranged 4a-homo-7,19-dinorandrostane derivatives with a 5α configuration.

Crystal structure of aristoserratine

1983 ◽  
Vol 36 (5) ◽  
pp. 1037 ◽  
Author(s):  
IRC Bick ◽  
MA Hai ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Circular Dichroism Spectrum ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
The Absolute ◽  
Circular Dichroïsm

The crystal structure of the alkaloid aristoserratine,* C20H24N2O, has been determined by single-crystal X-ray diffraction methods at 295 K, the structure being refined to a residual of 0.034 for 1107 independent 'observed' reflections. Crystals are monoclinic, P21, a 14.836(5), b 8.568(3), c 6.633(3) �, β 98.05(3)�, Z 2. The relative configuration is established and, by inference, by comparison of the circular dichroism spectrum with that of aristoteline, the absolute configuration is assigned.

Conclusive Determination of the Absolute Configuration of Chiral C60-Fullerenecis-3 Bisadducts by X-ray Crystallography and Circular Dichroism

2005 ◽  
Vol 44 (15) ◽  
pp. 2262-2265 ◽  
Author(s):  
Shunsuke Kuwahara ◽  
Kazuhiro Obata ◽  
Kazuhiro Yoshida ◽  
Takatoshi Matsumoto ◽  
Nobuyuki Harada ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute ◽  
Circular Dichroïsm

Synthesis of N-[(3-Amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] Derivatives of α-Amino Acids

2007 ◽  
Vol 72 (12) ◽  
pp. 1697-1706 ◽  
Author(s):  
Galina L. Levit ◽  
Victor P. Krasnov ◽  
Dmitriy A. Gruzdev ◽  
Alexander M. Demin ◽  
Iliya V. Bazhov ◽  
...  
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Alkyl Esters ◽  
X Ray ◽  
X Ray Crystallography ◽  
Carbodiimide Method ◽  
The Absolute ◽  
Derivatives Of

The N-[(3-amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] derivatives of α-amino acids were prepared starting from N-protected (Ac, Form, Bz, and Boc) 3-amino-1-(carboxymethyl)-o-carboranes and alkyl esters of natural α-amino acids using the carbodiimide method of coupling and removing the ester groups. All the amides obtained were diastereoisomeric mixtures. Some diastereoisomers were separated and the assignment of the absolute configuration of aminocarborane fragments was performed by X-ray crystallography.

scholarly journals 5-Amino-5-deoxy-2-C-hydroxymethyl-2,3-O-isopropylidene-L-lyxono-1,5-lactam

2007 ◽  
Vol 63 (3) ◽  
pp. o1409-o1411
Author(s):  
Michela Simone ◽  
George W. J. Fleet ◽  
Richard Bream ◽  
David J. Watkin
Keyword(s):  
Absolute Configuration ◽  
Catalytic Hydrogenation ◽  
Title Compound ◽  
Crystallographic Analysis ◽  
Starting Material ◽  
Relative Configuration ◽  
X Ray ◽  
Compound C ◽  
The Absolute

The relative configuration of the title compound, C9H14NO5, formed by catalytic hydrogenation of an azidolactone, has been established by X-ray crystallographic analysis. The absolute configuration was determined by the use of 2,3-O-isopropylidene-L-lyxono-1,4-lactone as the carbohydrate starting material.

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