scholarly journals Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O)”s: functionalization, rotational barriers and non-covalent interactions

2016 ◽  
Vol 12 ◽  
pp. 1453-1458 ◽  
Author(s):  
Golo Storch ◽  
Sebastian Pallmann ◽  
Frank Rominger ◽  
Oliver Trapp
Keyword(s):  
Adduct Formation ◽  
Enantioselective Catalysis ◽  
Cellulose Derivatives ◽  
Diphosphine Ligands ◽  
Rotational Barriers ◽  
Covalent Adduct ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Stereodynamic ligands offer intriguing possibilities in enantioselective catalysis. “NU-BIPHEPs” are a class of stereodynamic diphosphine ligands which are easily accessible via rhodium-catalyzed double [2 + 2 + 2] cycloadditions. This study explores the preparation of differently functionalized “NU-BIPHEP(O)” compounds, the characterization of non-covalent adduct formation and the quantification of enantiomerization barriers. In order to explore the possibilities of functionalization, we studied modifications of the ligand backbone, e.g., with 3,5-dichlorobenzoyl chloride. Diastereomeric adducts with Okamoto-type cellulose derivatives and on-column deracemization were realized on the basis of non-covalent interactions. Enantioselective dynamic HPLC (DHPLC) allowed for the determination of rotational barriers of ΔG ‡ 298K = 92.2 ± 0.3 kJ mol−1 and 99.5 ± 0.1 kJ mol−1 underlining the stereodynamic properties of “NU-BIPHEPs” and “NU-BIPHEP(O)s”, respectively. These results make the preparation of tailor-made functionalized stereodynamic ligands possible and give an outline for possible applications in enantioselective catalysis.

scholarly journals Tunable aziridinium ylide reactivity: non-covalent interactions enable divergent product outcomes

2021 ◽  
Author(s):  
Kate Nicastri ◽  
Soren Zappia ◽  
Jared Pratt ◽  
Julia Duncan ◽  
Ilia Guzei ◽  
...  
Keyword(s):  
Chemical Space ◽  
Steric Effects ◽  
Computational Studies ◽  
Rapid Preparation ◽  
Rotational Barriers ◽  
Wide Range ◽  
Non Covalent Interactions ◽  
Further Development ◽  
Covalent Interactions

Methods for rapid preparation of densely functionalized and stereochemically complex N-heterocyclic scaffolds are in demand for exploring potential new bioactive chemical space. This work describes experimental and computational studies to better understand the features of aziridinium ylides as intermediates for the synthesis of highly substituted dehydromorpholines. The development of this chemistry has enabled the extension of aziridinium ylide chemistry to the concomitant formation of both a C–N and a C–O bond in a manner that preserves the stereochemical information embedded in the substrate. The chemistry is tolerant of a wide range of functionalities that can be employed for DNA-encoded library (DEL) synthesis to prepare diverse libraries of heterocycles with potential bioactivity. In addition, we have uncovered several key insights that describe the importance of steric effects, rotational barriers around the C–N bond of the aziridinium ylide, and non-covalent interactions (NCIs) on the ultimate reaction outcome. These critical insights will assist in the further development of this chemistry to generate novel and complex N-heterocycles that will further expand complex amine chemical space.

scholarly journals Characterization of N⋯O non-covalent interactions involving σ-holes: “electrostatics” or “dispersion”

2016 ◽  
Vol 18 (43) ◽  
pp. 29946-29954 ◽  
Author(s):  
Rahul Shukla ◽  
Deepak Chopra
Keyword(s):  
Non Covalent Interactions ◽  
Pnicogen Bonds ◽  
Covalent Interactions ◽  
Oxygen Atoms

Exploring the possibility of formation of pnicogen bonds or chalcogen bonds by utilizing the σ-holes present on nitrogen and oxygen atoms in per-halo substituted complexes.

Bioactivation of Phenytoin by Human Cytochrome P450:  Characterization of the Mechanism and Targets of Covalent Adduct Formation

1997 ◽  
Vol 10 (9) ◽  
pp. 1049-1058 ◽  
Author(s):  
Andrew J. Munns ◽  
James J. De Voss ◽  
Wayne D. Hooper ◽  
Ronald G. Dickinson ◽  
Elizabeth M. J. Gillam
Keyword(s):  
Cytochrome P450 ◽  
Adduct Formation ◽  
Human Cytochrome ◽  
Covalent Adduct

scholarly journals The isolation and characterization of the high-molecular-weight glycoprotein from pig colonic mucus

1978 ◽  
Vol 173 (2) ◽  
pp. 569-578 ◽  
Author(s):  
T Marshall ◽  
A Allen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Quaternary Structure ◽  
Water Soluble ◽  
Isolation And Characterization ◽  
Nuclease Digestion ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
Equilibrium Centrifugation

1. A high-molecular-weight glycoprotein constitutes over 80% by weight of the total glycoprotein from water-soluble pig colonic mucus. 2. It was isolated from from nucleic acid and non-covalently bound protein by nuclease digestion followed by equilibrium centrifugation in a CsCl gradient. 3. The glycoprotein has the following composition by weight: fucose 10.4%; glucosamine 23.9%; galactosamine 8.3%; sialic acid 9.9%; galactose 20.8%; sulphate 3.0%; protein 13.3%; moisture about 10%. 4. The native glycoprotein has the high mol.wt. of 15×10(6). 5. Reduction of the native glycoprotein with 2-mercaptoethanol results in a glycoprotein of mol.wt. 6×10(6). 6. Pronase digestion removes 29% of the protein (3% of the glycoprotein) but none of the carbohydrate. 7. The molecular weight of the Pronase-digested glycoprotein is 1.5×10(6), which is halved to 0.76×10(6) on reduction with 2-mercaptoethanol. 8. The contribution of non-covalent interactions, disulphide bridges and the non-glycosylated peptide core to the quaternary structure of the glycoprotein are discussed and compared with the known structure of pig gastric glycoportein.

scholarly journals Manifold Dynamic Non-Covalent Interactions for Steering Molecular Assembly and Cyclization

2021 ◽  
Author(s):  
Shaotang Song ◽  
Jie Su ◽  
Lulu Wang ◽  
Zhen Xu ◽  
Chia-Hsiu Hsu ◽  
...  
Keyword(s):  
Real Space ◽  
Molecular Assembly ◽  
Biological Processes ◽  
Chemical Transformations ◽  
Molecular Assemblies ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
Space Characterization

Deciphering rich non-covalent interactions that govern many chemical and biological processes is crucial for the design of drugs and controlling molecular assemblies and their chemical transformations. However, real-space characterization of...

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