scholarly journals Highly Functional Group Tolerant, (E)-Selective Transfer Semihydrogenation of Alkynes Catalysed by Iridium Complex Bearing Unsymmetrical Ferrocene-Based Phosphine Ligand

2021 ◽  
Author(s):  
Rafał Kusy ◽  
Marcin Lindner ◽  
Jakub Wagner ◽  
Karol Grela
Keyword(s):  
Catalytic Activity ◽  
Steric Hindrance ◽  
Functional Group ◽  
Phosphine Ligand ◽  
Iridium Complex ◽  
Selective Transfer ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
The Common

Herein, we present (E)-selective transfer semihydrogenation of alkynes based on in situ generated iridium complex from [Ir(COD)Cl]2 and unsymmetrical ferrocene-based phosphine ligand in the presence of formic acid as a hydrogen donor. The catalytic system is distinguished by unprecedented chemoselectivity and exceptional stereoselectivity substantiated by the broad scope of test-ed substrates, including natural products derivatives. The uniform reaction conditions may be applied to various alkynes, owing to a lack of over-reduction. The intriguing difference in catalytic activity between unsymmetrical and symmetrical ferrocene-based ligands was attributed to diver-gent coordination and steric hindrance. The presented methodology constitutes a solution to the common limitations of the published catalytic systems.

scholarly journals Highly Functional Group Tolerant, (E)-Selective Transfer Semihydrogenation of Alkynes Catalysed by Iridium Complex Bearing Unsymmetrical Ferrocene-Based Phosphine Ligand

2021 ◽  
Author(s):  
Rafał Kusy ◽  
Marcin Lindner ◽  
Jakub Wagner ◽  
Karol Grela
Keyword(s):  
Catalytic Activity ◽  
Steric Hindrance ◽  
Functional Group ◽  
Phosphine Ligand ◽  
Iridium Complex ◽  
Selective Transfer ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
The Common

Herein, we present (E)-selective transfer semihydrogenation of alkynes based on in situ generated iridium complex from [Ir(COD)Cl]2 and unsymmetrical ferrocene-based phosphine ligand in the presence of formic acid as a hydrogen donor. The catalytic system is distinguished by unprecedented chemoselectivity and exceptional stereoselectivity substantiated by the broad scope of test-ed substrates, including natural products derivatives. The uniform reaction conditions may be applied to various alkynes, owing to a lack of over-reduction. The intriguing difference in catalytic activity between unsymmetrical and symmetrical ferrocene-based ligands was attributed to diver-gent coordination and steric hindrance. The presented methodology constitutes a solution to the common limitations of the published catalytic systems.

Phosphorus Promoted HZSM-5 Zeolites for the Coupling Transformation of Methanol with 1-Butene to Propylene

2020 ◽  
Author(s):  
Xiao-hua Tang ◽  
Rui-qiang Liu ◽  
Hai-feng Tian ◽  
Hui Li ◽  
fei zha ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Space Velocity ◽  
In Situ Synthesis ◽  
Synthetic Methods ◽  
Incipient Wetness Impregnation ◽  
Large Specific Surface Area ◽  
Reaction Conditions ◽  
Coupling Transformation ◽  
Incipient Wetness

Phosphorus promoted HZSM-5 zeolites (P-HZSM-5) were prepared by synthetic methods of incipient wetness impregnation and in-situ synthesis, respectively. It was characterized by the means of XRD, SEM, BET, TG and NH3-TPD. The P-HZSM-5 zeolite prepared by incipient wetness impregnation has a large specific surface area and pore size, and the weak acidity is remarkably increased. The catalytic activity of P-HZSM-5 for the coupling transformation of methanol with 1-butene to propylene was investigated. Under the reaction conditions of temperature at 550 ℃, pressure at 0.4 MPa, space velocity at 1800 mL/(gcath) and mole ratio of CH3OH/C4H8 to 1:1, the conversion of C4H8 can reach to 75.8%, and the selectivity and yield of propylene are 42.2% and 31.9%, respectively.

Radical Metal-Free Borylation of Aryl Iodides

Synthesis ◽  
2017 ◽  
Vol 49 (21) ◽  
pp. 4759-4768 ◽  
Author(s):  
Sandra Pinet ◽  
Mathieu Pucheault ◽  
Virginie Liautard ◽  
Mégane Debiais
Keyword(s):  
Steric Hindrance ◽  
Radical Mechanism ◽  
Electronic Effects ◽  
Simple Metal ◽  
Reaction Conditions ◽  
Metal Free ◽  
Aryl Iodides ◽  
Reaction Proceeds ◽  
Electronic Effects Of Substituents

A simple metal-free borylation of aryl iodides mediated by a fluoride sp2–sp3 diboron adduct is described. The reaction conditions are compatible with various functional groups. Electronic effects of substituents do not affect the borylation while steric hindrance does. The reaction proceeds via a radical mechanism in which pyridine serves to stabilize the boryl radicals, generated in situ.

scholarly journals Palladium Catalyzed α,β-Homodiarylation of Vinyl Esters in Aqueous Medium

2021 ◽  
Author(s):  
Ryszard Ostaszewski ◽  
Damian Trzepizur ◽  
Anna Brodzka ◽  
Dominik Koszelewski ◽  
Monika Wilk
Keyword(s):  
Catalytic Activity ◽  
Functional Group ◽  
Reaction Medium ◽  
Environmentally Benign ◽  
Vinyl Esters ◽  
Arylboronic Acid ◽  
Reaction Conditions ◽  
Mild Conditions ◽  
Palladium Catalyzed ◽  
One Step

Abstract A palladium catalyzed 1,2-diarylation of vinyl esters with sustainable arylbornic acids in water has been developed. This newly elaborated protocol features good functional group tolerance and provides a one-step access to 1,2-diaryletahol derivatives under mild reaction conditions. The presented reaction can be carried out in water smoothly without the addition of any ligands at ambient temperature what makes this procedure environmentally benign. The transformation occurs within a single catalytic cycle and is feasible due to the modification of transition metal catalytic activity through the influence of π-acceptor olefin (benzoquinone) as well as the polar protic reaction medium (water in particular). Moreover, the protocol allows to generate entire compounds libraries (highly profitable in medicinal chemistry) and utilizes sustainable arylboronic acid as coupling partners under mild conditions.

scholarly journals Copolymerization of Ethylene and 1-Hexene Catalyzed by the Zirconocene/Al(i-Bu)3/B(C6F5)3 Catalytic System

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Puyu Zhang ◽  
Yonghong Li ◽  
Yun Chai
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Catalytic System ◽  
Catalytic Systems ◽  
Catalytic Activities

AbstractCopolymerizations of ethylene/1-hexene were conducted using different zirconocene/AlR3/B(C6F5)3 catalytic systems at 50°C. When AlEt3 was used as alkylate agent, very low copolymerization activity was observed with both bridged catalyst Et[Ind]2ZrCl2 and unbridged zirconocene Cp2ZrCl2 in-situ activated with B(C6F5)3. In appropriate Al/Zr mole ratio using Al(i-Bu)3, the catalytic activities of both zirconocene catalytic systems were similar to those of sophisticated zirconocene/methylaluminoxane(MAO) catalytic system. The catalytic activities, comonomer incorporation and molecular weight of the copolymer synthesized with Et[Ind]2ZrCl2/Al(i-Bu)3/B(C6F5)3 were higher than those obtained with Cp2ZrCl2/Al(i- Bu)3/B(C6F5)3. The effect of the concentration of 1-hexene on catalytic activity, copolymer molecular weight, and comonomer incorporation was investigated. The complicated “co-monomer effect”, together with an increase in comonomer incorporation, a decrease in the copolymer molecular weight, was found when the comonomer concentration was increased.

Carbon Monoxide-Driven Osmium Catalyzed Reductive Amination Harvesting WGSR Power

2021 ◽  
Author(s):  
Klim O. Biriukov ◽  
Mikhail M. Vinogradov ◽  
Oleg I Afanasyev ◽  
Dmitry Vasilyev ◽  
Alexey Tsygankov ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Aqueous Solutions ◽  
Reductive Amination ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
Shift Reaction ◽  
Water Gas

Herein, we present the first example of Os-catalyzed efficient reductive amination under water-gas shift reaction conditions. The developed catalytic systems are formed in situ in aqueous solutions, employ as small...

In Situ Temperature-Programmed Diffuse Reflectance Infrared Fourier Transform Spectroscopy (TPDRIFTS) of V2O5/TiO2 Catalysts

1997 ◽  
Vol 51 (3) ◽  
pp. 416-422 ◽  
Author(s):  
M. A. Centeno ◽  
J. J. Benítez ◽  
P. Malet ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Fourier Transform ◽  
Diffuse Reflectance ◽  
Stage Iv ◽  
Fourier Transform Spectroscopy ◽  
Reaction Conditions ◽  
Water Desorption ◽  
Catalytic Systems ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

Temperature-programmed diffuse reflectance infrared Fourier transform spectroscopy (TPDRIFTS) is proposed to follow in situ temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) experiments of catalytic systems, as a method for observing relationships between the surface structure and the reducibility of the catalyst under the actual reaction conditions. TPDRIFTS studies of desorption and reduction of a conventional V2O5/TiO2 catalyst have been carried out, showing the presence in both processes of four stages. Both desorption and reduction experiments result in similar DRIFTS spectra for temperatures below 400 °C, accounting for two processes: (1) water desorption and (2) condensation of highly dispersed vanadium species in between V2O5 islands on the anatase surface. V2O5 reduction by H2 takes place between 400 and 680 °C, being characterized by elimination of the first-overtone bands of V= O groups. DRIFTS is shown to be a very powerful tool to characterize both hydrogen-consuming and nonconsuming processes such as O= migration above 725 °C (stage IV). Relationships between the area of V = O overtones bands obtained by TPDRIFTS and the oxidation state of vanadium are proposed as a method to estimate this parameter under actual reaction conditions.

In situ generation of functionality in a reactive binicotinic-acid-based ligand for the design of multi-functional copper(ii) complexes: syntheses, structures and properties

CrystEngComm ◽  
2015 ◽  
Vol 17 (8) ◽  
pp. 1871-1880 ◽  
Author(s):  
Dongsheng Deng ◽  
Hui Guo ◽  
Guohui Kang ◽  
Lufang Ma ◽  
Xu He ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Conditions ◽  
Strecker Reaction ◽  
Structures And Properties ◽  
In Situ Generation

Five copper binicotinic complexes have been synthesized depending on the reaction conditions. Complexes 1 and 2 display excellent catalytic activity for Strecker reaction of imines.

scholarly journals High-Performance Chlorine-Doped Cu2O Catalysts for the Ethynylation of Formaldehyde

Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 198
Author(s):  
Jie Gao ◽  
Guofeng Yang ◽  
Haitao Li ◽  
Mei Dong ◽  
Zhipeng Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Bond Strength ◽  
Reaction Temperature ◽  
Active Sites ◽  
High Performance ◽  
Lattice Structure ◽  
Reaction Conditions ◽  
Simple Strategy ◽  
Co Precipitation

The in situ formed Cu+ species serve as active sites in the ethynylation of formaldehyde. The key problem that needs to be solved in this process is how to avoid excessive reduction of Cu2+ to inactive metallic Cu, which tends to decrease the catalytic activity. In this work, Cl−-modified Cu2O catalysts with different Cl content were prepared by co-precipitation. The characterization results demonstrated that Cl− remained in the lattice structure of Cu2O, inducing the expansion of the Cu2O lattice and the enhancement of the Cu–O bond strength. Consequently, the reduction of Cu+ to Cu0 was effectively prevented in reductive media. Moreover, the activity and stability of Cu2O were significantly improved. The Cl− modification increased the yield of 1,4-butynediol (BD) from 73% to 94% at a reaction temperature of 90 °C. More importantly, the BD yield of Cl− modified Cu2O was still as high as 86% during the ten-cycle experiment, whereas the BD yield of Cu2O in the absence of Cl− decreased sharply to 17% at the same reaction conditions. This work provides a simple strategy to stabilize Cu+ in reductive media.

Formamide Catalysis Facilitates the Transformation of Aldehydes into Geminal Dichlorides

Synthesis ◽  
2019 ◽  
Vol 51 (12) ◽  
pp. 2474-2483 ◽  
Author(s):  
Peter Helmut Huy
Keyword(s):  
Nucleophilic Substitution ◽  
Substitution Reaction ◽  
Functional Group ◽  
Lewis Base ◽  
Base Catalyst ◽  
Reaction Conditions ◽  
Novel Method ◽  
In Situ Formation ◽  
Type Intermediate

Herein, a novel method for the transformation of aldehydes into geminal dichlorides based on phthaloyl chloride as reagent and N-formylpyrrolidine as Lewis base catalyst is disclosed. Given the mild reaction conditions, the current protocol is distinguished by high levels of functional group compatibility and scalability and is operationally simple. The in situ formation of a Vilsmeier Haack reagent type intermediate is likely to be essential for this organocatalytic nucleophilic substitution reaction.

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