Metal-dependent selective formation of calix[4]arene assemblies based on dynamic covalent chemistry

2021 ◽  
Author(s):  
Yoko Sakata ◽  
Ryo Tsuyuki ◽  
Shingo Sugimoto ◽  
Shigehisa Akine
Keyword(s):  
Dynamic Covalent Chemistry ◽  
Cone Conformation ◽  
Selective Formation

The reaction of calix[4]arene derivatives 1a,b bearing four salicylaldehyde moieties with 1,3-propanediamine gave macrocyclic trimers 5a,b, which have intramolecular bridges formed via the flattened cone conformation. In contrast, a capsular-shaped...

Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

2020 ◽  
Author(s):  
Shubham Deolka ◽  
Orestes Rivada Wheelaghan ◽  
Sandra Aristizábal ◽  
Robert Fayzullin ◽  
Shrinwantu Pal ◽  
...  
Keyword(s):  
Alkyl Group ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Terminal Alkyne ◽  
Alkyl Aryl ◽  
Metal Metal ◽  
The Stability ◽  
Selective Formation ◽  
Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

Gold Catalyzed Hydroamination of Propargylic Alcohols: Controlling Divergent Reaction Pathways to Access 1,3-Aminoalcohols, 3-Hydroxyketones or 3-Aminoketones

2018 ◽  
Author(s):  
Victor Laserna ◽  
Tom Sheppard
Keyword(s):  
Gold Catalysis ◽  
Reaction Pathways ◽  
High Yield ◽  
Reaction Conditions ◽  
Propargylic Alcohols ◽  
Catalytic Quantity ◽  
Selective Formation ◽  
General Method

A versatile approach to the valorization of propargylic alcohols is reported, enabling controlled access to three different products from the same starting materials. Firstly, a general method for the hydroamination of propargylic alcohols with anilines is described using gold catalysis to give 3-hydroxy imines with complete regioselectivity. These 3-hydroxyimines can be reduced to give 1,3-aminoalcohols with high syn seletivity. Alternatively, by using a catalytic quantity of aniline, 3-hydroxyketones can be obtained in high yield directly from propargylic alcohols. Further manipulation of the reaction conditions enables the selective formation of 3-aminoketones via a rearrangement/hydroamination pathway.<br>

Formation and Trapping of the Thermodynamically Unfavoured Inverted-Hemicucurbit[6]uril

2019 ◽  
Author(s):  
Elena Prigorchenko ◽  
Sandra Kaabel ◽  
Triin Narva ◽  
Anastassia Baškir ◽  
Maria Fomitšenko ◽  
...  
Keyword(s):  
Complex Formation ◽  
Combinatorial Chemistry ◽  
Trifluoroacetic Acid ◽  
Chloride Anion ◽  
Binding Affinities ◽  
Dynamic Covalent Chemistry ◽  
Reaction Selectivity ◽  
Low Concentration ◽  
Dynamic Combinatorial Chemistry ◽  
First Time

Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and <i>cis</i>-<i>N,N'</i>-cyclohexa-1,2-diylurea formation of <i>inverted-cis</i>-cyclohexanohemicucurbit[6]uril (<i>i-cis</i>-cycHC[6]) can be induced at the expense of thermodynamically favoured <i>cis</i>-cyclohexanohemicucurbit[6]uril (<i>cis</i>-cycHC[6]). The formation of <i>i-cis-</i>cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-aided dynamic combinatorial chemistry and continuous removal of the formed cycHC[6] macrocycles from the equilibrating solution by precipitation. Notably, the <i>i-cis</i>-cycHC[6] was isolated with 33% yield. Different binding affinities of three diastereomeric <i>i-cis</i>-, <i>cis</i>-cycHC[6] and their chiral isomer (<i>R,R</i>)-cycHC[6] for trifluoroacetic acid demonstrate the influence of macrocycle geometry on complex formation.

scholarly journals Spontaneous macrocyclization through multiple dynamic cyclic aminal formation

2021 ◽  
Author(s):  
Daniel Carbajo ◽  
Antonio Jesús Ruiz-Sánchez ◽  
Francisco Nájera Albendín ◽  
Ezequiel Perez-Inestrosa ◽  
Ignacio Alfonso
Keyword(s):  
Dynamic Covalent Chemistry

The use of aminals in dynamic covalent chemistry is slightly underexplored, probably due to their inherent instability. Here we report the spontaneous [2+2] macrocyclization of tetrakis(aminals). Their unexpected stability and...

Selective Formation of a Supramolecular Coordination Complex in the Nanometre Scale with a Ferrocene-based Phospholane Ligand

2021 ◽  
Author(s):  
Reinhard Hoy ◽  
Toni Grell ◽  
Peter Lönnecke ◽  
Evamarie Hey-Hawkins
Keyword(s):  
Coordination Complex ◽  
Supramolecular Coordination ◽  
Selective Formation

A straightforward synthesis of the tetradentate phospholane ligand 1 is reported. The 2:1 [M:L] reaction of 1 with [AuCl(tht)] (tht = tetrahydrothiophen) resulted in a 4:2 [M:L] supramolecular coordination complex...

scholarly journals An Iron-Based Dehydration Catalyst for Selective Formation of Styrene

ACS Catalysis ◽  
2021 ◽  
pp. 10885-10891
Author(s):  
Olaf Nachtigall ◽  
Andrew I. VanderWeide ◽  
William W. Brennessel ◽  
William D. Jones
Keyword(s):  
Iron Based ◽  
Selective Formation

scholarly journals Effect of Ni(NO3)2 Pretreatment on the Pyrolysis of Organsolv Lignin Derived from Corncob Residue

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 23
Author(s):  
Wenli Wang ◽  
Yichen Liu ◽  
Yue Wang ◽  
Longfei Liu ◽  
Changwei Hu
Keyword(s):  
Sustainable Development ◽  
Fixed Bed ◽  
Value Added ◽  
Bio Oil ◽  
Fuels And Chemicals ◽  
Gas Products ◽  
Work Samples ◽  
Nickel Species ◽  
The Impact ◽  
Selective Formation

The thermal degradation of lignin for value-added fuels and chemicals is important for environment improvement and sustainable development. The impact of pretreatment and catalysis of Ni(NO3)2 on the pyrolysis behavior of organsolv lignin were studied in the present work. Samples were pyrolyzed at 500 ∘C with an upward fixed bed, and the characteristics of bio-oil were determined. After pretreatment by Ni(NO3)2, the yield of monophenols increased from 23.3 wt.% to 30.2 wt.% in “Ni-washed” and decreased slightly from 23.3 wt.% to 20.3 wt.% in “Ni-unwashed”. Meanwhile, the selective formation of vinyl-monophenols was promoted in “Ni-unwashed”, which indicated that the existence of nickel species promoted the dehydration of C-OH and breakage of C-C in pyrolysis. In comparison with “Water”, HHV of bio-oil derived from “Ni-unwashed” slightly increased from 27.94 mJ/kg to 28.46 mJ/kg, suggesting that the lowering of oxygen content in bio-oil is associated with improved quality. Furthermore, the content of H2 in gas products dramatically increased from 2.0% to 7.6% and 17.1%, respectively.

scholarly journals Effects of Glymes on the Distribution of Mg(B10H10) and Mg(B12H12) from the Thermolysis of Mg(BH4)2

Inorganics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 41
Author(s):  
Ba L. Tran ◽  
Tamara N. Allen ◽  
Mark E. Bowden ◽  
Tom Autrey ◽  
Craig M. Jensen
Keyword(s):  
Nmr Analysis ◽  
Relative Ratio ◽  
11B Nmr ◽  
Selective Formation

We examined the effects of concentrations and identities of various glymes, from monoglyme up to tetraglyme, on H2 release from the thermolysis of Mg(BH4)2 at 160–200 °C for 8 h. 11B NMR analysis shows major products of Mg(B10H10) and Mg(B12H12); however, their relative ratio is highly dependent both on the identity and concentration of the glyme to Mg(BH4)2. Selective formation of Mg(B10H10) was observed with an equivalent of monoglyme and 0.25 equivalent of tetraglyme. However, thermolysis of Mg(BH4)2 in the presence of stoichiometric or greater equivalent of glymes can lead to unselective formation of Mg(B10H10) and Mg(B12H12) products or inhibition of H2 release.

scholarly journals Selective formation of apical oxygen vacancies in La2−xSrxCuO4

2017 ◽  
Vol 1 (5) ◽  
Author(s):  
Gideok Kim ◽  
Georg Christiani ◽  
Gennady Logvenov ◽  
Sungkyun Choi ◽  
Hun-Ho Kim ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Apical Oxygen ◽  
Selective Formation

scholarly journals Catalytic Systems Based on Cp2ZrX2 (X = Cl, H), Organoaluminum Compounds and Perfluorophenylboranes: Role of Zr,Zr- and Zr,Al-Hydride Intermediates in Alkene Dimerization and Oligomerization

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 39
Author(s):  
Lyudmila V. Parfenova ◽  
Pavel V. Kovyazin ◽  
Almira Kh. Bikmeeva ◽  
Eldar R. Palatov
Keyword(s):  
Diffusion Coefficients ◽  
Organoaluminum Compounds ◽  
Zirconium Hydride ◽  
Nmr Studies ◽  
Catalytic Systems ◽  
Selective Formation

The activity and chemoselectivity of the Cp2ZrCl2-XAlBui2 (X = H, Bui) and [Cp2ZrH2]2-ClAlEt2 catalytic systems activated by (Ph3C)[B(C6F5)4] or B(C6F5)3 were studied in reactions with 1-hexene. The activation of the systems by B(C6F5)3 resulted in the selective formation of head-to-tail alkene dimers in up to 93% yields. NMR studies of the reactions of Zr complexes with organoaluminum compounds (OACs) and boron activators showed the formation of Zr,Zr- and Zr,Al-hydride intermediates, for which diffusion coefficients, hydrodynamic radii, and volumes were estimated using the diffusion ordered spectroscopy DOSY. Bis-zirconium hydride clusters of type x[Cp2ZrH2∙Cp2ZrHCl∙ClAlR2]∙yRnAl(C6F5)3−n were found to be the key intermediates of alkene dimerization, whereas cationic Zr,Al-hydrides led to the formation of oligomers.

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