Absolute chirality of the γ-polymorph of glycine: correlation of the absolute structure with the optical rotation

2012 ◽  
Vol 48 (48) ◽  
pp. 6031 ◽  
Author(s):  
Kazuhiko Ishikawa ◽  
Masahito Tanaka ◽  
Toshiya Suzuki ◽  
Akiko Sekine ◽  
Tsuneomi Kawasaki ◽  
...  
Keyword(s):  
Optical Rotation ◽  
The Absolute ◽  
Absolute Chirality ◽  
Absolute Structure

Total synthesis and absolute structure of N55, a positive modulator of GLP-1 signaling

2020 ◽  
Vol 18 (43) ◽  
pp. 8899-8907
Author(s):  
Nai-Pin Lin ◽  
Rong-Jie Chein
Keyword(s):  
Total Synthesis ◽  
Positive Modulator ◽  
Glucagon Like Peptide ◽  
The Absolute ◽  
Glucagon Like Peptide 1 ◽  
Absolute Structure

The absolute structure of N55, a positive modulator of Glucagon-like peptide-1 (GLP-1) signaling, was determined by a 7-step total synthesis with 29% overall yield.

scholarly journals Absolute structure determination of compounds with axial and planar chirality using the crystalline sponge method

2015 ◽  
Vol 6 (7) ◽  
pp. 3765-3768 ◽  
Author(s):  
Shota Yoshioka ◽  
Yasuhide Inokuma ◽  
Manabu Hoshino ◽  
Takashi Sato ◽  
Makoto Fujita
Keyword(s):  
Structure Determination ◽  
Asymmetric Syntheses ◽  
Planar Chirality ◽  
The Absolute ◽  
Absolute Structure

The absolute structure determination of compounds with axial and planar chirality obtained by recently developed asymmetric syntheses was achieved using the crystalline sponge method without using any reference compounds or synthetic modifications.

scholarly journals The absolute structure and synthesis of wenjine isolated from Curcuma wenyujin.

1991 ◽  
Vol 39 (4) ◽  
pp. 854-856 ◽  
Author(s):  
Ji-Fu GAO ◽  
Ji-Hong XIE ◽  
Kenzo HARIMAYA ◽  
Takeshi KAWAMATA ◽  
Yoichi IITAKA ◽  
...  
Keyword(s):  
The Absolute ◽  
Absolute Structure

Chiral Crystalline Sponges for the Absolute Structure Determination of Chiral Guests

2017 ◽  
Vol 139 (33) ◽  
pp. 11341-11344 ◽  
Author(s):  
KaKing Yan ◽  
Ritesh Dubey ◽  
Tatsuhiko Arai ◽  
Yasuhide Inokuma ◽  
Makoto Fujita
Keyword(s):  
Structure Determination ◽  
The Absolute ◽  
Absolute Structure

scholarly journals Absolute Configuration Sensing of Chiral Aryl- and Aryloxy-Propionic Acids by Biphenyl Chiroptical Probes

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 154
Author(s):  
Stefania Vergura ◽  
Stefano Orlando ◽  
Patrizia Scafato ◽  
Sandra Belviso ◽  
Stefano Superchi
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Environmental Pollutants ◽  
Red Shift ◽  
Electronic Circular Dichroism ◽  
Configuration Assignment ◽  
Clear Sign ◽  
The Absolute ◽  
Circular Dichroïsm

The absolute configuration of chiral 2-aryl and 2-aryloxy propionic acids, which are among the most common chiral environmental pollutants, has been readily and reliably established by either electronic circular dichroism spectroscopy or optical rotation measurements employing suitably designed 4,4′-disubstituted biphenyl probes. In fact, the 4,4′-biphenyl substitution gives rise to a red shift of the diagnostic electronic circular dichroism signal of the biphenyl A band employed for the configuration assignment, removing its overlap with other interfering dichroic bands and allowing its clear sign identification. The largest A band red shift, and thus the most reliable results, are obtained by employing as a probe the 4,4′-dinitro substituted biphenylazepine 3c. The method was applied to the absolute configuration assignment of 2-arylpropionic acids ibuprofen (1a), naproxen (1b), ketoprofen (1c) and flurbiprofen (1d), as well as to the 2-aryloxypropionic acids 2-phenoxypropionic acid (2a) and 2-naphthoxypropionic acid (2b). This approach, allowing us to reveal the sample’s absolute configuration by simple optical rotation measurements, is potentially applicable to online analyses of both the enantiomeric composition and absolute configuration of these chiral pollutants.

Enzymatic Synthesis of Four Stereoisomers of 7-0xo-biopterin and Determination of the Absolute Structure of Ichthyopterin

Pteridines ◽  
1990 ◽  
Vol 2 (3) ◽  
pp. 151-156 ◽  
Author(s):  
Shin Ichiro Takikawa ◽  
Sadao Matsuura
Keyword(s):  
Enzymatic Synthesis ◽  
Side Chain ◽  
Side Chains ◽  
Enzymatic Conversion ◽  
Cd Spectra ◽  
The Absolute ◽  
Chiral Centers ◽  
Absolute Structure

Summary Enzymatic conversion of stereoisomers of biopterin (3a-d) to the 7-oxo-biopterin isomers (4a-d) was performed with a new pterin 7-oxidase extracted from carp skin. The chiral centers of the 6-side chains of biopterin isomers were preserved during the conversion, and the four possible stereoisomers of 7-oxo-biopterin (4a-d) were obtained from the corresponding biopterin isomers (3a-d). HPLC and CD spectra studies showed that natural ichthyopterin is 2-amino-6-(L-erythro-1',2' -dihydroxypropyl)-4, 7(3H,8H)-pteridinedione (4a) which has the same L-erythro structure at the side chain as natural biopterin (3a). This fact suggests that ichthyopterin is biologically derived from biopterin in these fishes.

scholarly journals Chiral Resolution and Absolute Configuration of 3α,6β-Dicinnamoyloxytropane and 3α,6β-Di(1-ethyl-1H-pyrrol-2-ylcarbonyloxy)tropane, Constituents of Erythroxylum Species

2014 ◽  
Vol 9 (1) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Marcelo A. Muñoz ◽  
Solange Arriagada ◽  
Pedro Joseph-Nathan
Keyword(s):  
Stationary Phase ◽  
Natural Product ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Normal Phase ◽  
Vibrational Circular Dichroism ◽  
Chiral Resolution ◽  
Case Characteristic ◽  
The Absolute

Chiral resolution of (±)-3α,6β-dicinnamoyloxytropane (1) and (±)-3α,6β-di(1-methyl-1 H-pyrrol-2-ylcarbonyloxy)tropane (2), prepared by esterification of (±)-3α,6β-tropanediol (3), was achieved using an amylose-derived HPLC stationary phase and normal phase conditions. The corresponding vibrational circular dichroism (VCD) spectra provided the absolute configuration of the enantiomers as (-)-(3 R,6 R)-1, (+)-(3S,6S)- 1, (-)-(3 R,6 R)-2 and (+)-(3S,6S)- 2. In each case, characteristic VCD bands for the absolute configuration determination of the 3α,6β-tropandiol esters were observed. While the absolute configuration of natural 1, previously isolated from Erythroxylum hypericifolium, could not be established due to the lack of literature optical rotation values, that of catuabine E, previously isolated from E. vacciniifolium, is now assigned as (-)-(3 R,6 R)-2 by comparison with the optical rotation values of the prepared samples and the reported rotation of the natural product.

scholarly journals Structure of Equilenin at 100 K: an estrone-related steroid

2017 ◽  
Vol 73 (8) ◽  
pp. 1223-1226
Author(s):  
Christopher S. Frampton ◽  
David D. MacNicol
Keyword(s):  
Hydrogen Bonds ◽  
Resonant Scattering ◽  
Methyl Group ◽  
Axis Direction ◽  
Envelope Conformation ◽  
The Absolute ◽  
Absolute Structure

The structure of the estrone-related steroid, Equilenin, C18H18O2 (systematic name 3-hydroxy-13-methyl-11,12,13,14,15,16-hexahydrocyclopenta[a]phenanthren-17-one), has been determined at 100 K. The crystals are orthorhombic, P212121, and the absolute structure of the molecule in the crystal has been determined by resonant scattering [Flack parameter = −0.05 (4)]. The C atoms of the A and B rings are almost coplanar, with an r.m.s. deviation from planarity of 0.0104 Å. The C ring has a sofa conformation, while the D ring has an envelope conformation with the methine C atom as the flap. The keto O atom and the methyl group are translated 0.78 and 0.79 Å, respectively, from the equivalent positions on 17β-estrone. In the crystal, molecules are linked by O—H...O hydrogen bonds, forming chains parallel to the c-axis direction.

(3aS,5aR,6R,8aR)-3a-Hydroxy-5a-methyl-6-[(1R,2E,4R)-1,4,5-trimethyl-2-hexen-1-yl]-3a,4,5,5a,6,7,8,8a-octahydro-2H-cyclopenta[e]benzofuran-2-one

2007 ◽  
Vol 63 (11) ◽  
pp. o4196-o4196
Author(s):  
Wen-liang Wang ◽  
Hong-wen Tao ◽  
Wei Sun ◽  
Qian-Qun Gu ◽  
Wei-Ming Zhu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Absolute Configuration ◽  
Title Compound ◽  
Optical Rotation ◽  
Side Chain ◽  
Compound C ◽  
Extended Chain ◽  
Halotolerant Fungus ◽  
The Absolute

The title compound, C21H32O3, also known as dimethylincisterol A3, was isolated from halotolerant fungus THW-18. It is composed of three fused rings and a side chain. In the crystal structure, the molecules interact with each other via O—H...O hydrogen bonds, resulting in an extended chain along the b axis. The absolute configuration was assigned from the measured optical rotation and reference to the literature.

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