Novel dioxolene nickel complexes with sterically hindered diazabutadienes. Coupling of aza-ligands coordinated to nickel

2019 ◽  
Vol 48 (28) ◽  
pp. 10516-10525 ◽  
Author(s):  
Michael P. Bubnov ◽  
Vladimir K. Cherkasov ◽  
Irina A. Teplova ◽  
Nickolay O. Druzhkov ◽  
Ivan D. Grishin ◽  
...  
Keyword(s):  
Nickel Complexes ◽  
Methyl Group ◽  
Sterically Hindered

Coupling of nickel complexes containing N,N′-disubstituted-2,3-dimethyl-1,4-diazabutadiene-1,3 occurs through the methyl group of the latter in nonpolar media in the presence of free o-quinone.

Ligand-centred oxidative chemistry in sterically hindered salen complexes: an interesting case with nickel

2016 ◽  
Vol 45 (27) ◽  
pp. 10866-10877 ◽  
Author(s):  
F. Thomas
Keyword(s):  
Nickel Complexes ◽  
Redox Chemistry ◽  
Interesting Case ◽  
Salen Complexes ◽  
Sterically Hindered ◽  
Salen Ligands

Salen ligands are ubiquitous chelators, whose nickel complexes readily undergo a ligand-centred redox chemistry in non-coordinating solvents.

scholarly journals Less hindered ligands give improved catalysts for the nickel catalysed Grignard cross-coupling of aromatic ethers

2018 ◽  
Vol 8 (1) ◽  
pp. 328-334 ◽  
Author(s):  
Gavin J. Harkness ◽  
Matthew L. Clarke
Keyword(s):  
Nickel Complexes ◽  
Cross Coupling ◽  
Grignard Reagents ◽  
Sterically Hindered

The challenging reaction of unactivated ortho-substituted aromatic ethers with Grignard reagents has been found to be most effectively catalysed using nickel complexes of less sterically hindered ligands.

Use of [13C-methyl]Tropinone to follow the fate of the methyl group during calystegine formation in root cultures of Solanum dulcamara (Solanaceae)

Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
TA Bartholomeusz ◽  
R Molinié ◽  
A Roscher ◽  
AC Freydank ◽  
B Dräger ◽  
...  
Keyword(s):  
Root Cultures ◽  
Solanum Dulcamara ◽  
Methyl Group

STEROIDSTRUKTUR UND LEBERTOXIZITÄT

1967 ◽  
Vol 54 (1) ◽  
pp. 73-84 ◽  
Author(s):  
H. L. Krüskemper ◽  
G. Noell
Keyword(s):  
Alkaline Phosphatase ◽  
Liver Function ◽  
Blood Coagulation ◽  
Electrophoretic Pattern ◽  
Coagulation Factors ◽  
Blood Coagulation Factors ◽  
Methyl Group ◽  
Liver Functions ◽  
Male Subjects ◽  
Androstane Derivatives

ABSTRACT In male subjects investigations have been carried out regarding the effect of C1- and C17-methylated androstane derivatives (20 mg per day, orally, two weeks) on liver functions (parameters: activities of GPT, GOT, alkaline phosphatase and cholinesterase in serum; electrophoretic pattern; blood coagulation factors V, VII, X and prothrombin; BSP-retention). In addition to the well known hepatotropic action of 17α-alkylated C-19-steroids a quasi-axial 1α-methyl configuration (in 1α-methylandrost-2-en-17β-ol) definitely increased BSP-retention and several coagulation factors. These steroid effects decreased gradually when a methyl group was introduced in C1 equatorially (1-methylandrost-1-en-17β-ol-3-one) or quasi-equatorially (1β-methylandrost-2-en-17β-ol), the latter compound completely lacking from any influence on parameters of liver function under investigation.

Spatiotemporal Control of Amide Radicals During Photocatalysis

2020 ◽  
Author(s):  
Shogo Mori ◽  
Takahiro Aoki ◽  
Kaliyamoorthy Selvam ◽  
Shunichi Fukuzumi ◽  
Jieun Jung ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Nickel Complex ◽  
Nickel Complexes ◽  
Semiconductor Material ◽  
Radical Reactions ◽  
Substitution Reactions ◽  
Carbon Neutrality ◽  
Spatiotemporal Control ◽  
Scalable Production ◽  
Salt Waste

Despite the continuing popularity of radical reactions in organic synthesis, much remains to be explored in this area. Herein, we describe how spatiotemporal control can be exerted over the formation and reactivity of divergent exchangeable formamide radicals using nickel complexes with a semiconductor material (TiO<sub>2</sub>) under irradiation from near-UV–Vis light. Depending on the bipyridine ligand used and the quantity of the nickel complex that is hybridized on or nonhydridized over the TiO<sub>2</sub> surface, these radicals selectively undergo substitution reactions at the carbon center of carbon–bromine bonds that proceed via three different pathways. As the scalable production of formamides from CO<sub>2</sub> does not produce salt waste, these methods could add a new dimension to the search for carbon neutrality through the indirect incorporation of CO<sub>2</sub> into organic frameworks.

Nickel-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Hydrazones

2019 ◽  
Author(s):  
Leiyang Lv ◽  
Dianhu Zhu ◽  
Zihang Qiu ◽  
Jianbin Li ◽  
Chao-Jun Li
Keyword(s):  
Catalytic Method ◽  
Unsaturated Hydrocarbons ◽  
Carbon Nucleophiles ◽  
Aryl Aldehydes ◽  
Aldehydes And Ketones ◽  
Sterically Hindered

Hydroalkylation of unsaturated hydrocarbons with unstablized carbon nucleophiles is difficult and remains a major challenge. The disclosed examples so far mainly focused on the involvement of heteroatom and/or stabilized carbon nucleophiles as efficient reaction partners. Reported here is an unprecedented regioselective nickel-catalyzed hydroalkylation of 1,3-dienes with hydrazones, generated in situ from abundant aryl aldehydes and ketones and acted as both the sources of unstabilized carbanions and hydride. With this strategy, both terminal and sterically hindered internal dienes are hydroalkylated efficiently in a highly selective manner, thus providing a novel and reliable catalytic method to construct challenging C(sp3)-C(sp3) bonds.

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

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