Results 81 to 90 of about 2,257 (201)

Remote Conformational Control of a Chloride‐Binding Site

ChemistryEurope
Peptide foldamers, each with a stereogenic C‐terminal bis(squaramide) separated from an N‐terminal amino acid “controller” by an α‐aminoisobutyric acid (Aib) tetramer, have been shown to bind chloride.
Rhodri Ll. Evans, Luis Martínez‐Crespo, Benedicte Doerner, Rosa M. Gomila, George F. S. Whitehead, Antonio Frontera, Simon J. Webb   +6 more
doaj   +1 more source

Asymmetric Mannich Reaction: Synthesis of Novel Chiral 5-(substituted aryl)-1,3,4-Thiadiazole Derivatives with Anti-Plant-Virus Potency

Heterocyclic Communications, 2019
A series of novel chiral 5-(substituted aryl)-1,3,4-thiadiazole derivatives was synthesized in an enantioselective three-component Mannich reaction using cinchona alkaloid squaramide catalyst with excellent enantioselectivities (up to >99% enantiomeric ...
Bai Song, Zhu Yunying, Wu Qin
doaj   +1 more source

On the Role of Hydrogen Bond Strength and Charge Transfer in an On‐Water Diels–Alder Reaction: Semiempirical and Free Energy Calculations

Journal of Computational Chemistry, Volume 47, Issue 20, July 30, 2026.
Matched Diels‐Alder dienophiles at a water interface reveal that on‐water catalysis depends on hydrogen‐bond quality rather than hydrogen‐bond count. Oxygen preserves charge‐transfer coupling and lowers the free‐energy barrier, whereas sulfur disrupts this coupling and promotes an asynchronous pathway.
Andrés Henao, Yomna Gohar, René Wilhelm, Thomas D. Kühne   +3 more
wiley   +1 more source

A theoretical study of aromaticity in squaramide complexes with anions

[eng] A systematic estimation of aromaticity in squaramide complexes with anions has been studied using structural and magnetic criteria. Results based on Nucleus Independent Chemical Shift (NICS) predict that squaramide is less aromatic than its ...
Frontera, A., Costa, A., Garau, C., Quiñonero, D., Prohens, R., Ballester, P., Deyà, P.M.   +6 more
core   +1 more source

Asymmetric Synthesis of Hydrophenanthrenones Bearing Multiple Stereogenic Centers via Squaramide-Catalyzed Domino 1,4-/1,4-Addition Desymmetrization Sequence

, 2023
An unprecedented stereoselective route for procuring tetrahydrophenanthren-2(1H)-ones bearing up to five contiguous stereogenic centers has been accomplished. A bifunctional squaramide enables a domino 1,4-/1,4-addition desymmetrization reaction sequence
Pankaj Chauhan, Manisha Sharma, Tamanna (12431111), Pankaj Chauhan (559259), Manisha Sharma (1751905), Tamanna   +5 more
core   +1 more source

One-Pot Synthesis of Novel Chiral β-Amino Acid Derivatives by Enantioselective Mannich Reactions Catalyzed by Squaramide Cinchona Alkaloids

Molecules, 2013
An efficient one-pot synthesis of novel β-amino acid derivatives containing a thiadiazole moiety was developed using a chiral squaramide cinchona alkaloid as organocatalyst.
Kankan Zhang, Xueping Liang, Ming He, Jian Wu, Yuping Zhang, Wei Xue, Linhong Jin, Song Yang, Deyu Hu   +8 more
doaj   +1 more source

Synthesis of Benzopyran Atropisomers via Electrophilic Halogenation

European Journal of Organic Chemistry, Volume 29, Issue 27, 17 July 2026.
We report a halogenation‐based method for the synthesis of axially chiral benzopyrans, tolerating diverse substituents and halogens (Br, Cl, and I). A double bromination gives bisbenzopyrans with two stereogenic axes. Preliminary enantioselective conditions yield benzopyran atropisomer with up to 56% ee.
Alix Bourhis, Expédite Yen‐Pon, Jean Rodriguez, Damien Bonne   +3 more
wiley   +1 more source

Squaramide Calix[4]pyrroles for Anion Transport [PDF]

In this paper we demonstrate the transmembrane chloride transport properties of a series of calix[4]pyrroles appended with squaramide moieties for the first time.
Fares, Mohamed, Du, Jonathan, Hibbs, David E., Wang, Patrick, Gale, Philip A.   +4 more
core   +1 more source

Enantioselective Michael Addition of Cyclic β-Diones to α,β-Unsaturated Enones Catalyzed by Quinine-Based Organocatalysts

Molecules, 2017
An enantioselective (52–98% ee) Michael addition between cyclic β-diones and α,β-unsaturated enones was established in the presence of quinine-based primary amine or squaramide.
Qingqing Wang, Wei Wang, Ling Ye, Xuejun Yang, Xinying Li, Zhigang Zhao, Xuefeng Li   +6 more
doaj   +1 more source

Mechanochemistry Meets Catalysis: Metal Complexes for Greener Organic Transformations

Angewandte Chemie, Volume 138, Issue 29, 13 July 2026.
Mechanochemistry is redefining metal catalysis by controlling catalyst formulation, speciation, and deployment. This Review shows how milling, LAG, RAM, and TSE enable rapid metal‐complex assembly, distinctive catalytic manifolds, and scalable synthesis beyond solution chemistry.
Sourav Behera, Francesco Basoccu, Andrea Porcheddu   +2 more
wiley   +1 more source