scholarly journals The effects of introducing sterically demanding aryl substituents in [Cu(N^N)(P^P)]+ complexes

2017 ◽  
Vol 46 (19) ◽  
pp. 6379-6391 ◽  
Author(s):  
Fabian Brunner ◽  
Stefan Graber ◽  
Yann Baumgartner ◽  
Daniel Häussinger ◽  
Alessandro Prescimone ◽  
...  
Keyword(s):  
Aryl Substituent ◽  
Sterically Demanding ◽  
Sterically Hindered

[Cu(6-Arbpy)(POP)][PF6] and [Cu(6-Arbpy)(xantphos)][PF6] compounds in which Ar is a sterically hindered aryl substituent are described; structural and solution dynamical consequences of the bulky groups are investigated.

Effects of a Sterically Demanding P–Aryl Substituent in Phosphole and 7–Phosphanorbornene Chemistry

1996 ◽  
Vol 109 (1-4) ◽  
pp. 433-436 ◽  
Author(s):  
Louis D. Quin ◽  
Alexey S. Ionkin ◽  
Rajdeep Kalgutkar ◽  
György Keglevich
Keyword(s):  
Aryl Substituent ◽  
Sterically Demanding

Hydroaminoalkylation of sterically hindered alkenes with N,N-dimethyl anilines using a scandium catalyst

2019 ◽  
Vol 17 (7) ◽  
pp. 2013-2019 ◽  
Author(s):  
Jianhong Su ◽  
Yiqun Zhou ◽  
Xin Xu
Keyword(s):  
Bond Formation ◽  
Sterically Demanding ◽  
Sterically Hindered

Atom-economical and regioselective C(sp3)–C(sp3) bond formation has been achieved by C(sp3)–H alkylation of N,N-dimethyl anilines with sterically demanding alkenes by scandium catalysis.

Sterically demanding zinc(ii) phthalocyanines: synthesis, optical, electrochemical, nonlinear optical, excited state dynamics studies

2014 ◽  
Vol 2 (9) ◽  
pp. 1711-1722 ◽  
Author(s):  
Debasis Swain ◽  
Radhakant Singh ◽  
Varun Kumar Singh ◽  
Narra Vamsi Krishna ◽  
Lingamallu Giribabu ◽  
...  
Keyword(s):  
Excited State ◽  
Nonlinear Optical ◽  
Excited State Dynamics ◽  
Sterically Demanding ◽  
Sterically Hindered

Sterically hindered molecules like the title compounds, combined with their strong NLO coefficients make them potential candidates for photonic applications.

ChemInform Abstract: Effects of a Sterically Demanding-P-aryl Substituent in Phosphole and 7-Phosphanorbornene Chemistry

ChemInform ◽  
2010 ◽  
Vol 28 (11) ◽  
pp. no-no
Author(s):  
L. D. QUIN ◽  
A. S. IONKIN ◽  
R. KALGUTKAR ◽  
G. KEGLEVICH
Keyword(s):  
Aryl Substituent ◽  
Sterically Demanding

Regioselective Gas-Phase n-Butane Transfer Dehydrogenation via Silica-Supported Pincer-Iridium Complexes

2020 ◽  
Author(s):  
Boris Sheludko ◽  
Cristina Castro ◽  
Chaitanya Khalap ◽  
Thomas Emge ◽  
Alan Goldman ◽  
...  
Keyword(s):  
Gas Phase ◽  
Active Site ◽  
Lower Cost ◽  
Open Systems ◽  
Iridium Complexes ◽  
Terminal Olefin ◽  
Molecular Precursors ◽  
Sterically Demanding ◽  
Olefin Production ◽  
Steam Cracking

<b>Abstract:</b> The production of olefins via on-purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica-supported pincer-iridium complexes of the form [(≡SiO-<sup>R4</sup>POCOP)Ir(CO)] (<sup>R4</sup>POCOP = κ<sup>3</sup>-C<sub>6</sub>H<sub>3</sub>-2,6-(OPR<sub>2</sub>)<sub>2</sub>) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution-phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes <a>[(≡SiO-<i><sup>t</sup></i><sup>Bu4</sup>POCOP)Ir(CO)] </a>(<b>1</b>) and [(≡SiO-<i><sup>i</sup></i><sup>Pr4</sup>PCP)Ir(CO)] (<b>2</b>) were synthesized via immobilization of molecular precursors. These complexes were used for gas-phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77%. The results indicate that the active site is conserved upon immobilization.

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>

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands

2019 ◽  
Vol 38 (24) ◽  
pp. 4615-4624 ◽  
Author(s):  
Alexander N. Selikhov ◽  
Andrey S. Shavyrin ◽  
Anton V. Cherkasov ◽  
Georgy K. Fukin ◽  
Alexander A. Trifonov
Keyword(s):  
Thermally Stable ◽  
Sterically Demanding ◽  
Half Sandwich
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