scholarly journals Elucidation of the Relationship between CD Cotton Effects and the Absolute Configuration of Sixteen Stereoisomers of Spiroheterocyclic-Lactams

Marine Drugs ◽  
2018 ◽  
Vol 16 (7) ◽  
pp. 223 ◽  
Author(s):  
Takeshi Yamada ◽  
Tetsuya Kajimoto ◽  
Takashi Kikuchi ◽  
Reiko Tanaka
Keyword(s):  
Absolute Configuration ◽  
Cotton Effects ◽  
The Absolute ◽  
The Relationship

The Relationship between the CD Cotton Effect and the Absolute Configuration of FD-838 and Its Seven Stereoisomers

2010 ◽  
Vol 75 (12) ◽  
pp. 4146-4153 ◽  
Author(s):  
Takeshi Yamada ◽  
Hiroki Kitada ◽  
Tetsuya Kajimoto ◽  
Atsushi Numata ◽  
Reiko Tanaka
Keyword(s):  
Absolute Configuration ◽  
Cotton Effect ◽  
The Absolute ◽  
The Relationship

Absolute Configuration of Chiral 1,3,4,5-Tetrahydro-2H-l,5-benzodiazepin-2-ones

1998 ◽  
Vol 53 (4) ◽  
pp. 485-487 ◽  
Author(s):  
Mashooda Hasan ◽  
Tanveer Ahmad Nizami ◽  
Abdul Malik ◽  
Claus Ohlendorf ◽  
Wolfgang Hiller ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectra ◽  
X Ray ◽  
Cotton Effects ◽  
The Absolute

X-ray studies are carried out to correlate the Cotton effects in CD spectra with the absolute configuration of a series of previously reported chiral 1,3,4,5-tetrahydro-2H-1 ,5-benzodazepin-2-ones.

Identification of iridals as piscicidal components of Iridaceous plants and their conformations associated with CD spectra

1997 ◽  
Vol 75 (6) ◽  
pp. 734-741 ◽  
Author(s):  
Yoko Miyake ◽  
Hideyuki Ito ◽  
Takashi Yoshida
Keyword(s):  
Spectral Analysis ◽  
Molecular Modeling ◽  
Absolute Configuration ◽  
Cd Spectra ◽  
Cotton Effects ◽  
The Absolute

Upon toxicity-guided fractionation of the extractives of the Irisgermanica rhizomes and I. japonica roots using killie-fish (Oryziaslatipes), 12 iridal-type triterpenoids including three new iridals were isolated as piscicidal constituents. Of these, iriflorental, iripallidal, and γ-irigermanal exhibited a potent activity at a concentration of less than 1 μg/mL. The structures of new iridals, irisgermanicals A (7), B (10), and C (11), from I. germanica were elucidated based on the spectral analysis. The absolute configuration at C-13 of the known spiroiridal (15) from I. japonica, which remained to be solved, was defined as R on the basis of NOE measurement. The hitherto unreported correlation between the Cotton effects in the CD spectra of some iridals and their conformations was also discussed on the basis of molecular modeling. Keywords: Irisgermanica, Irisjaponica, iridal-type triterpenoid, piscicidal activity, CD spectra.

scholarly journals Assignment of Absolute Configuration of Bromoallenes by Vacuum-Ultraviolet Circular Dichroism (VUVCD)

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1296
Author(s):  
Taiki Umezawa ◽  
Nakaba Mizutani ◽  
Koichi Matsuo ◽  
Yuugo Tokunaga ◽  
Fuyuhiko Matsuda ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Vacuum Ultraviolet ◽  
Specific Rotation ◽  
Ultraviolet Region ◽  
Cotton Effects ◽  
The Absolute ◽  
Circular Dichroïsm ◽  
Absolute Stereochemistry ◽  
Unambiguous Assignment

A new application of vacuum-ultraviolet circular dichroism (VUVCD), which enables the measurement of CD spectra in the vacuum-ultraviolet region (140–200 nm), for the assignment of the absolute configurations of bromoallenes is described. Bromoallene moieties are found in natural products obtained from many marine organisms. To date, the absolute configuration of bromoallenes has been assigned almost exclusively with Lowe’s rule, which is based on specific rotation. However, exceptions to Lowe’s rule have been reported arising from the presence of other substituents with large specific rotations. For the unambiguous assignment of the absolute configuration of the bromoallene moiety with its characteristic absorption wavelength at 180–190 nm due to the π–π* transition, VUVCD was applied to four pairs of bromoallene diastereomers prepared by modifying the synthetic scheme of omaezallene. The VUVCD spectra clearly showed positive or negative Cotton effects around 180–190 nm according to the configuration of the bromoallene employed, revealing the potential of VUVCD for determining absolute stereochemistry.

A New Series of Diterpenes from Australian Spongia Species

1979 ◽  
Vol 32 (4) ◽  
pp. 867 ◽  
Author(s):  
R Kazlauskas ◽  
PT Murphy ◽  
RJ Wells ◽  
K Noack ◽  
WE Oberhansli ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Spectral Methods ◽  
Barrier Reef ◽  
X Ray ◽  
The Absolute ◽  
New Compounds ◽  
The Relationship ◽  
Circular Dichroïsm

Great Barrier Reef sponges of the genus Spongia have yielded eight closely related tetracyclic furanoditerpenes. The structures, assigned on the basis of spectral methods, have been confirmed by a single-crystal X-ray analysis of one of the metabolites and the relative stereochemical features have been defined. The absolute configuration of this metabolite was determined by circular dichroism, which allowed the relationship between the eight new compounds to be determined.

Rola Avarského Kaganátu Pri Vzniku Slovenčiny

2018 ◽  
Vol 69 (2) ◽  
pp. 199-236
Author(s):  
Martin Braxatoris ◽  
Michal Ondrejčík
Keyword(s):  
Slavic Language ◽  
The West ◽  
The North ◽  
Danube Region ◽  
The Absolute ◽  
North Edge ◽  
The Relationship ◽  
Slovak Language

Abstract The paper proposes a basis of theory with the aim of clarifying the casual nature of the relationship between the West Slavic and non-West Slavic Proto-Slavic base of the Slovak language. The paper links the absolute chronology of the Proto-Slavic language changes to historical and archaeological information about Slavs and Avars. The theory connects the ancient West Slavic core of the Proto-Slavic base of the Slovak language with Sclaveni, and non-West Slavic core with Antes, which are connected to the later population in the middle Danube region. It presumes emergence and further expansion of the Slavic koiné, originally based on the non-West Slavic dialects, with subsequent influence on language of the western Slavic tribes settled in the north edge of the Avar Khaganate. The paper also contains a periodization of particular language changes related to the situation in the Khaganate of that time.

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