Preparation of a 6.alpha.-substituted optically pure steroid with thiophene as the A ring via asymmetric induction. A circular dichroism study

1981 ◽  
Vol 46 (13) ◽  
pp. 2655-2660 ◽  
Author(s):  
Anton A. Macco ◽  
Henk M. Buck
Keyword(s):  
Circular Dichroism ◽  
Asymmetric Induction ◽  
Optically Pure ◽  
Circular Dichroïsm

Circular Dichroism Determination of the Conformation of Optically Pure 1-(1-Naphthyl)ethylamino-Substituted 1,3,5-Triazine Derivatives

1998 ◽  
Vol 63 (24) ◽  
pp. 8765-8768 ◽  
Author(s):  
Anna Iuliano ◽  
Emanuela Franchi ◽  
Gloria Uccello-Barretta ◽  
Piero Salvadori
Keyword(s):  
Circular Dichroism ◽  
Triazine Derivatives ◽  
Optically Pure ◽  
Circular Dichroïsm

Optical Activity of Symmetric Compounds in Chiral Media. I. Induced Circular Dichroism of Unbound Substrates

1971 ◽  
Vol 49 (4) ◽  
pp. 624-631 ◽  
Author(s):  
L. D. Hayward ◽  
R. N. Totty
Keyword(s):  
Circular Dichroism ◽  
Carbonyl Compounds ◽  
Optical Rotation ◽  
Optically Active ◽  
Asymmetric Induction ◽  
Azo Compounds ◽  
Induced Circular Dichroism ◽  
Chiral Media ◽  
Circular Dichroïsm ◽  
Rotational Strengths

In the presence of chiral environment compounds, C, optical rotation is induced in symmetric substrates, S, and may be detected as circular dichroism in the electronic spectra of the solutions. Thus the n − π* transitions of symmetric and racemic carbonyl compounds, and of symmetric nitro and azo compounds, become optically active when these S are dissolved in chiral hydrocarbons, ketones, or carbinols, or in solutions of these C in achiral solvents. The rotational strengths of the induced circular dichroism bands of S are solvent, temperature, and concentration dependent. Only limited correlation of the sign and magnitude of the induced bands with the stereochemistry of C and S is evident on the data so far accumulated. Halogenated achiral solvents enhance the intensity, and, in some cases reverse the sign of the induced bands.A new mechanism of asymmetric induction is proposed in which specific bonding of C with S is not prerequisite.

scholarly journals Isolation and Absolute Configurations of Diversiform C17, C21 and C25 Terpenoids from the Marine Sponge Cacospongia sp.

Marine Drugs ◽  
2018 ◽  
Vol 17 (1) ◽  
pp. 14 ◽  
Author(s):  
Xingwang Zhang ◽  
Ping-Lin Li ◽  
Guo-Fei Qin ◽  
Shengying Li ◽  
Nicole de Voogd ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Cell Lines ◽  
Optical Rotation ◽  
Human Tumor ◽  
Chiral Hplc ◽  
Pure Compounds ◽  
New Compounds ◽  
First Time ◽  
Optically Pure ◽  
Circular Dichroïsm

Chemical investigation of MeOH extract of a South China Sea sponge Cacospongia sp. yielded 15 terpenoids belonging to three different skeleton-types, including the unusual C17 γ-lactone norditerpenoids (1–3), the rare C21 pyridine meroterpenoid (7), and the notable C25 manoalide-type sesterterpenoids (4–6, 8–10). Compounds 1–5 were initially obtained as enantiomers, and were further separated to be optically pure compounds (1a, 1b, 2a, 2b, 3a-r, 3b-r, 4a, 4b, 5a and 5b) by chiral HPLC, with a LiAlH4 reduction aid for 3. Compounds 3a/3b (a pair of inseparable enantiomers), 4a, 5a, 6, and 7 were identified as new compounds, while 1a/1b and 2a/2b were obtained from a natural source and were determined for their absolute configurations for the first time. This is also the first time to encounter enantiomers of the well-known manoalide-type sesterterpenoids from nature. The structures with absolute configurations of the new compounds were unambiguously determined by comprehensive methods including HR-ESI-MS and NMR data analysis, optical rotation comparison, experimental and calculated electronic circular dichroism (ECD), and Mo2(OAc)4 induced circular dichroism (ICD) methods. The cytotoxicity of the isolates against selected human tumor cell lines was evaluated, however, the tested compounds showed no activity against selected cell lines.

Direct Monitoring of the Asymmetric Induction of Solid-Phase Catalysis Using Circular Dichroism: Diamine–CuI-Catalyzed Asymmetric Henry Reaction

2006 ◽  
Vol 118 (36) ◽  
pp. 6124-6127 ◽  
Author(s):  
Takayoshi Arai ◽  
Masahiko Watanabe ◽  
Akitsugu Fujiwara ◽  
Naota Yokoyama ◽  
Akira Yanagisawa
Keyword(s):  
Circular Dichroism ◽  
Solid Phase ◽  
Asymmetric Induction ◽  
Henry Reaction ◽  
Circular Dichroïsm

Vibrational Circular Dichroism Study of Optically Pure Cryptophane-A

2006 ◽  
Vol 128 (16) ◽  
pp. 5533-5540 ◽  
Author(s):  
Thierry Brotin ◽  
Dominique Cavagnat ◽  
Jean-Pierre Dutasta ◽  
Thierry Buffeteau
Keyword(s):  
Circular Dichroism ◽  
Vibrational Circular Dichroism ◽  
Optically Pure ◽  
Circular Dichroïsm
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