Results 91 to 100 of about 56,768 (286)

Light‐Gated Control of Brownian Rotation by a Molecular Motor

Angewandte Chemie, EarlyView.
A light‐driven molecular motor acts as a reversible steric gate for a nearby Brownian rotor. Photoisomerization switches the rotor between fast and hindered rotational regimes by modulating steric congestion around the rotational axis. The motor–rotor architecture enables a five‐order‐of‐magnitude difference in the rotational barrier, demonstrating ...
Lukáš Severa, Kateřina Bezděková, Katarina Majerová Varga, Guillaume Bastien, Miroslav Stroka, Ivana Císařová, Martin Dračínský, Jiří Kaleta   +7 more
wiley   +2 more sources

Stereoselectivity of In Vivo Processes and Bioactivity of Farrerol Enantiomers

Molecules
Farrerol, a bioactive compound found in Folium Rhododendri daurici, demonstrates various biological and pharmacological effects. Nevertheless, the stereoselectivity of in vivo processes and bioactivity between its enantiomers have not been thoroughly ...
Lirong Chen, Tang Yan, Dongting Huang, Wei Xu, Yongjing Liu, Xiaoying Wang, Hua Li   +6 more
doaj   +1 more source

One-Dimensional 13C NMR Is a Simple and Highly Quantitative Method for Enantiodiscrimination

Molecules, 2018
The discrimination of enantiomers of mandelonitrile by means of 1D 13C NMR and with the aid of the chiral solvating agent (S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol (TFAE) is presented.
Peter P. Lankhorst, Jozef H. J. van Rijn, Alexander L. L. Duchateau   +2 more
doaj   +1 more source

Sequence‐Controlled Helical Ladder Polymers: Impact of Stereochemical Sequence on Helical Geometry and Chiral Recognition

Angewandte Chemie, EarlyView.
Nature programs distinct secondary structures and functions through subtle stereochemical differences, as exemplified by amylose and cellulose. Translating this principle into synthetic ladder polymers, stereochemical sequence control gives rise to diastereomeric coil‐ and ribbon‐type helices with complementary chiral recognition, demonstrating ...
Tomoyuki Ikai, Kanta Wakabayashi, Masaya Yoshida, Kosuke Oki, Eiji Yashima   +4 more
wiley   +2 more sources

Z‐Retentive Enantioselective Rh‐Catalyzed Hydroarylation of E,Z‐Dienes

Angewandte Chemie, EarlyView.
The Rh‐catalyzed hydroarylation of conjugated E,Z‐dienoates is found to proceed with high selectivity for addition to the E‐alkene unit. Mechanistic analysis of this Z‐retentive process points towards preferred binding of the E‐alkene unit to a Rh‐aryl species to give rise to the observed selectivity and that Rh‐enolate protonolysis to be turnover ...
Wesley McNutt, Hima Kozhummal, Abdullah Al‐Mashqbeh, Alex Brown, Rylan J. Lundgren   +4 more
wiley   +2 more sources

Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates

Czech Journal of Food Sciences, 2002
Protein hydrolysates produced by hydrochloric acid hydrolysis were analysed for 3-chloropropane-1,2-diol and its enantiomers. It was found that (R)-3-chloropropane-1,2-diol and (S)-3-chloropropane-1,2-diol were present in the hydrolysates in equimolar ...
J. Velíšek, M. Doležal, C. Crews, T. Dvořák   +3 more
doaj   +1 more source

Chiroptical Switching by Stereoselective Photochemical Sigmatropic Rearrangements: Experimental Realization of Calderoselectivity

Angewandte Chemie, EarlyView.
Calderoselectivity is established as a stereochemical principle for sigmatropic rearrangements. A homoannulene‐based chiroptical photoswitch undergoes a photochemical [1,11] sigmatropic rearrangement with control of the acyl movement on top of the cyclic π system.
Anne Krenkel, Frederike Beyer, Malte Feßner, Trung Tran Ngoc, Tobias Rüffer, Dominik Hornig, Martin Breugst, Christian Merten, Johannes F. Teichert   +8 more
wiley   +2 more sources

β‐C(sp3)—H Arylierung Aliphatischer Sulfonamide

Angewandte Chemie, EarlyView.
Das erste Protokoll zur β‐C(sp3)—H‐Aktivierung/Funktionalisierung aliphatischer Sulfonamide wird beschrieben. Die Arylierung solcher Substrate wird durch den Einsatz von N‐Acetylthioether‐Liganden ermöglicht und zeichnet sich durch ein breites Substratspektrum sowohl hinsichtlich des Sulfonamid‐Substrats als auch des Arylierungsreagenzes aus.
Friedrich Jurk, Isaac G. Sonsona, Manuel van Gemmeren   +2 more
wiley   +1 more source

Enantioselective Separation of 4,8-DHT and Phytotoxicity of the Enantiomers on Various Plant Species

Molecules, 2016
As a candidate for bioherbicide, 4,8-dihydroxy-1-tetralone (4,8-DHT) was isolated from Caryospora callicarpa epicarp and its two enantiomers, S-(+)-isosclerone and R-(−)-regiolone, were separated by chiral high-performance liquid chromatography (HPLC) on
Li Yang, Xiao-Yan Ma, Xiao Ruan, De-An Jiang, Cun-De Pan, Qiang Wang   +5 more
doaj   +1 more source

The effect of amino acid enantiomers on activity of selected enzymes in soil

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2011
This work was aimed to test the effect of selected amino acid enantiomers on activity of casein-protease and acid phosphomonoesterase in soil. Casein-protease was selected due to its key role in nitrogen mineralization and acid phosphomonoesterase due to
Peter Dundek, Ladislav Holík, Valerie Vranová, Klement Rejšek, Pavel Formánek   +4 more
doaj   +1 more source