scholarly journals σ or π? Bonding interactions in a series of rhenium metallotetrylenes

2021 ◽  
Vol 50 (6) ◽  
pp. 2083-2092
Author(s):  
Erik T. Ouellette ◽  
Ambre Carpentier ◽  
I. Joseph Brackbill ◽  
Trevor D. Lohrey ◽  
Iskander Douair ◽  
...  
Keyword(s):  
Multiple Bonding ◽  
Metathesis Reactions ◽  
Low Valent

Salt metathesis reactions between a low-valent rhenium(i) complex and a series of amidinate-supported tetrylenes led to rhenium metallotetrylenes with varying extents of Re–E multiple bonding.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

Nickel-Catalyzed Inter- and Intramolecular Carbon-Sulfur Bond Metathesis by Reversible Arylation

2019 ◽  
Author(s):  
Tristan Delcaillau ◽  
Alessandro Bismuto ◽  
Zhong Lian ◽  
Bill Morandi
Keyword(s):  
Good Yield ◽  
Functional Group ◽  
Product Formation ◽  
Single Bond ◽  
Ring Closing Metathesis ◽  
Catalytic Systems ◽  
Metathesis Reactions ◽  
New Applications ◽  
Further Development ◽  
Sulfur Bond

A nickel-catalyzed carbon-sulfur bond metathesis has been developed to access high-value thioethers. 1,2-bis(dicyclohexylphosphino)ethane (dcype) is essential to promote this highly functional group tolerant reaction. Further, synthetically challenging macrocycles could be obtained in good yield in an unusual example of ring-closing metathesis which does not involve alkene bonds. In-depth organometallic studies support a reversible Ni(0)-Ni(II) pathway to product formation. Overall, this work does not only disclose a more sustainable and more functional group tolerant alternative to previous catalytic systems based on Pd, but also presents new applications and mechanistic information which are highly relevant to the further development and application of unusual single bond metathesis reactions.

scholarly journals Facile synthesis of novel, known, and low-valent transition metal phosphates via reductive phosphatization

2021 ◽  
Author(s):  
Niklas Stegmann ◽  
Hilke Petersen ◽  
Claudia Weidenthaler ◽  
Wolfgang Schmidt
Keyword(s):  
Transition Metal ◽  
Oxidation States ◽  
Facile Synthesis ◽  
Metal Phosphates ◽  
Low Valent

Novel and known low valent transition metal phosphates (TMPs) are accessible via a novel and facile pathway. The method allows syntheses of TMPs also with reduced oxidation states. The key...

scholarly journals Low-valent dialkoxytitanium(ii): a useful tool for the synthesis of functionalized seven-membered ring compounds

2021 ◽  
Vol 57 (29) ◽  
pp. 3603-3606
Author(s):  
Florent Bodinier ◽  
Youssouf Sanogo ◽  
Janick Ardisson ◽  
Marie-Isabelle Lannou ◽  
Geoffroy Sorin
Keyword(s):  
Grignard Reagent ◽  
Membered Ring ◽  
Ring Compounds ◽  
Low Valent

Herein, we describe unprecedented access to all-carbon or heterocyclic seven-membered ring frameworks from 1,8-ene-ynes promoted by inexpensive low-valent titanium(ii) species, readily available from a combination of Ti(OiPr)4 and Grignard reagent.

scholarly journals Glycan-to-Glycan Binding: Molecular Recognition through Polyvalent Interactions Mediates Specific Cell Adhesion

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 397
Author(s):  
Gradimir Misevic ◽  
Emanuela Garbarino
Keyword(s):  
Cell Adhesion ◽  
Plasma Membranes ◽  
Specific Cell ◽  
Cellular Interactions ◽  
New Paradigm ◽  
Tumor Cell Adhesion ◽  
Self Recognition ◽  
Structural And Functional Properties ◽  
Low Valent

Glycan-to-glycan binding was shown by biochemical and biophysical measurements to mediate xenogeneic self-recognition and adhesion in sponges, stage-specific cell compaction in mice embryos, and in vitro tumor cell adhesion in mammals. This intermolecular recognition process is accepted as the new paradigm accompanying high-affinity and low valent protein-to-protein and protein-to-glycan binding in cellular interactions. Glycan structures in sponges have novel species-specific sequences. Their common features are the large size >100 kD, polyvalency >100 repeats of the specific self-binding oligosaccharide, the presence of fucose, and sulfated and/or pyruvylated hexoses. These structural and functional properties, different from glycosaminoglycans, inspired their classification under the glyconectin name. The molecular mechanism underlying homophilic glyconectin-to-glyconectin binding relies on highly polyvalent, strong, and structure-specific interactions of small oligosaccharide motifs, possessing ultra-weak self-binding strength and affinity. Glyconectin localization at the glycocalyx outermost cell surface layer suggests their role in the initial recognition and adhesion event during the complex and multistep process. In mammals, Lex-to-Lex homophilic binding is structure-specific and has ultra-weak affinity. Cell adhesion is achieved through highly polyvalent interactions, enabled by clustering of small low valent structure in plasma membranes.

{MI(CO)X(CNArDArF2)4} (DArF = 3,5-(CF3)2C6H3; M = Re and Tc; X = Br and Cl) Complexes: Convenient Platforms for the Synthesis of Low-Valent Rhenium and Technetium Compounds

2021 ◽  
Author(s):  
Federico Salsi ◽  
Michael Neville ◽  
Myles Drance ◽  
Adelheid Hagenbach ◽  
Joshua S. Figueroa ◽  
...  
Keyword(s):  
Low Valent

Activation of Nitrogen-Rich Substrates by Low-Valent, Redox-Active Aluminum Species

2021 ◽  
Vol 40 (4) ◽  
pp. 490-499
Author(s):  
Weixing Chen ◽  
Vladimir A. Dodonov ◽  
Vladimir G. Sokolov ◽  
Li Liu ◽  
Evgeny V. Baranov ◽  
...  
Keyword(s):  
Redox Active ◽  
Active Aluminum ◽  
Low Valent

Self-Healable Polyurethane Elastomer Based on Dual Dynamic Covalent Chemistry Using Diels–Alder “Click” and Disulfide Metathesis Reactions

2021 ◽  
Vol 3 (2) ◽  
pp. 847-856
Author(s):  
Prasanta Kumar Behera ◽  
Sagar Kumar Raut ◽  
Prantik Mondal ◽  
Shrabana Sarkar ◽  
Nikhil K. Singha
Keyword(s):  
Diels Alder ◽  
Polyurethane Elastomer ◽  
Dynamic Covalent Chemistry ◽  
Metathesis Reactions
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