scholarly journals Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

2021 ◽  
Vol 17 ◽  
pp. 1689-1697
Author(s):  
Susanne M Fischer ◽  
Simon Renner ◽  
A Daniel Boese ◽  
Christian Slugovc
Keyword(s):  
Room Temperature ◽  
Oxidation Stability ◽  
Catalyst Loading ◽  
Strong Impact ◽  
Michael Reactions ◽  
Solvent Free Conditions ◽  
Michael Acceptor ◽  
Test Reactions ◽  
Michael Acceptors ◽  
The Impact

Electron-rich triarylphosphines, namely 4-(methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP), outperform commonly used triphenylphosphine (TPP) in catalyzing oxa-Michael additions. A matrix consisting of three differently strong Michael acceptors and four alcohols of varying acidity was used to assess the activity of the three catalysts. All test reactions were performed with 1 mol % catalyst loading, under solvent-free conditions and at room temperature. The results reveal a decisive superiority of TMTPP for converting poor and intermediate Michael acceptors such as acrylamide and acrylonitrile and for converting less acidic alcohols like isopropanol. With stronger Michael acceptors and more acidic alcohols, the impact of the more electron-rich catalysts is less pronounced. The experimental activity trend was rationalized by calculating the Michael acceptor affinities of all phosphine–Michael acceptor combinations. Besides this parameter, the acidity of the alcohol has a strong impact on the reaction speed. The oxidation stability of the phosphines was also evaluated and the most electron-rich TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar masses of about 1200 g/mol at room temperature are accessible. Polymerizations carried out at 80 °C resulted in macromolecules containing a considerable share of Rauhut–Currier-type repeat units and consequently lower molar masses were obtained.

scholarly journals Electron Rich Triarylphosphines as Nucleophilic Catalysts for Oxa-Michael Reactions

2021 ◽  
Author(s):  
Susanne Fischer ◽  
Simon Renner ◽  
Adrian Daniel Böse ◽  
Christian Slugovc
Keyword(s):  
Room Temperature ◽  
Oxidation Stability ◽  
Strong Impact ◽  
Michael Adduct ◽  
Michael Additions ◽  
Michael Reactions ◽  
Repeat Units ◽  
Michael Acceptor ◽  
Michael Acceptors ◽  
Reaction Speed

Herein, we study the activity of methoxysubstituted arylphosphines (4-methoxy-phenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP) in catalyzing oxa-Michael additions in comparison to commonly used triphenylphosphine (TPP). Acrylonitrile, acryl amide and divinyl sulfone are used as Michael acceptors and propargyl alcohol, allyl alcohol, n-propanol and i-propanol are assessed as Michael donors. In many cases, catalyst loadings of only 1 mol% in respect to the Michael acceptor are sufficient to provide full conversion towards the Michael adduct in 24 h at room temperature. Generally, TMTPP is the most active catalyst in all cases. The experimental activity trend was rationalized by calculating the Michael acceptor affinities of all phosphine – Michael acceptor combinations. Besides this parameter, the acidity of the alcohol has a strong impact on the reaction speed. The oxidation stability of the phosphines was evaluated and electron richest TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar masses of about 1200 g/mol at room temperature are accessible. Polymerizations carried out at 80 °C resulted in macromolecules containing a considerable share of Rauhut-Currier type repeat units and consequently lower molar masses were obtained.

scholarly journals Electron Rich Triarylphosphines as Nucleophilic Catalysts for Oxa-Michael Reactions

2021 ◽  
Author(s):  
Susanne Fischer ◽  
Simon Renner ◽  
Adrian Daniel Böse ◽  
Christian Slugovc
Keyword(s):  
Room Temperature ◽  
Oxidation Stability ◽  
Strong Impact ◽  
Michael Adduct ◽  
Michael Additions ◽  
Michael Reactions ◽  
Repeat Units ◽  
Michael Acceptor ◽  
Michael Acceptors ◽  
Reaction Speed

Herein, we study the activity of methoxysubstituted arylphosphines (4-methoxy-phenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP) in catalyzing oxa-Michael additions in comparison to commonly used triphenylphosphine (TPP). Acrylonitrile, acryl amide and divinyl sulfone are used as Michael acceptors and propargyl alcohol, allyl alcohol, n-propanol and i-propanol are assessed as Michael donors. In many cases, catalyst loadings of only 1 mol% in respect to the Michael acceptor are sufficient to provide full conversion towards the Michael adduct in 24 h at room temperature. Generally, TMTPP is the most active catalyst in all cases. The experimental activity trend was rationalized by calculating the Michael acceptor affinities of all phosphine – Michael acceptor combinations. Besides this parameter, the acidity of the alcohol has a strong impact on the reaction speed. The oxidation stability of the phosphines was evaluated and electron richest TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar masses of about 1200 g/mol at room temperature are accessible. Polymerizations carried out at 80 °C resulted in macromolecules containing a considerable share of Rauhut-Currier type repeat units and consequently lower molar masses were obtained.

Highly Efficient Michael Reactions of Nitroolefins by Grinding Means

2019 ◽  
Vol 16 (3) ◽  
pp. 449-457 ◽  
Author(s):  
Dong-Xiao Cui ◽  
Yue-Dan Li ◽  
Jun-Chao Zhu ◽  
Yan-Yan Jia ◽  
Ai-Dong Wen ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Room Temperature ◽  
Michael Reaction ◽  
Building Blocks ◽  
Solvent Free ◽  
Michael Additions ◽  
Highly Efficient ◽  
Michael Reactions ◽  
Michael Adducts ◽  
Solvent Free Conditions

Aim and Objective: The direct β-functionalization of trans-β-nitroolefins by Michael reaction is regarded as an efficient way to provide precursors for β-functional amines. However, Michael additions by grinding means with solvent-free conditons are rarely reported. We have developed facile access to β-functional nitroalkanes by grinding means under solvent-free conditions. Materials and Methods: From commercially available materials including ethyl 2-nitroacetate, alkyl 2-cyanoacetates and malononitrile, the grinding reactions between these above-mentioned activated methylenecompounds and various trans-β-nitroolefins were performed at room temperature and solvent-free conditions. Results: A highly efficient direct Michael reaction of nitroolefins by simple grinding means has been developed. Various trans-nitrostyrenes were easily converted into corresponding β-functional nitroalkanes in excellent yields within 5~10 min (up to 36 examples). Conclusion: Herein, we have developed a simple and efficient way to β-functional nitroalkanes through Michael reactions by grinding means. The grinding Michael reaction is fast, clean and stable and these Michael adducts could be easily converted into the other amino compounds served as building blocks in organic synthesis.

Determining Michael Acceptor Reactivity from Kinetic, Mechanistic, and Computational Analysis for the Base-catalyzed Thiol-Michael Reaction

2021 ◽  
Author(s):  
Sijia Huang ◽  
Kangmin Kim ◽  
Grant Musgrave ◽  
Marcus Sharp ◽  
Jasmine Sinha ◽  
...  
Keyword(s):  
Computational Analysis ◽  
Michael Reaction ◽  
Computational Study ◽  
Michael Reactions ◽  
Michael Acceptor ◽  
Michael Acceptors

A combined experimental and computational study of the reactivities of seven commonly used Michael acceptors paired with two thiols within the framework of photobase-catalyzed thiol-Michael reactions is reported. The kinetic...

When Do Psychopathic Traits Affect Cooperative Behavior?: An Iterated Prisoner's Dilemma Experimental Study

2020 ◽  
Author(s):  
M Testori ◽  
M Kempf ◽  
RB Hoyle ◽  
Hedwig Eisenbarth
Keyword(s):  
Prisoner's Dilemma ◽  
Cooperative Behavior ◽  
Prisoner’S Dilemma ◽  
Selection Procedure ◽  
Psychopathic Traits ◽  
Strong Impact ◽  
Iterated Prisoner's Dilemma ◽  
Human Decision ◽  
The Impact ◽  
Iterated Prisoner’S Dilemma

© 2019 Hogrefe Publishing. Personality traits have been long recognized to have a strong impact on human decision-making. In this study, a sample of 314 participants took part in an online game to investigate the impact of psychopathic traits on cooperative behavior in an iterated Prisoner's dilemma game. We found that disinhibition decreased the maintenance of cooperation in successive plays, but had no effect on moving toward cooperation after a previous defection or on the overall level of cooperation over rounds. Furthermore, our results underline the crucial importance of a good model selection procedure, showing how a poor choice of statistical model can provide misleading results.

Enantioselective Michael Addition of Malonates to Enones

2020 ◽  
Vol 24 (7) ◽  
pp. 746-773
Author(s):  
Péter Bakó ◽  
Tamás Nemcsok ◽  
Zsolt Rapi ◽  
György Keglevich
Keyword(s):  
Michael Addition ◽  
Activity Relationship ◽  
Chalcone Derivatives ◽  
Michael Additions ◽  
Michael Reactions ◽  
Structure Activity ◽  
Cyclic Enones ◽  
Michael Acceptors ◽  
Relationship Of ◽  
Enantioselective Catalysts

: Many catalysts were tested in asymmetric Michael additions in order to synthesize enantioenriched products. One of the most common reaction types among the Michael reactions is the conjugated addition of malonates to enones making it possible to investigate the structure–activity relationship of the catalysts. The most commonly used Michael acceptors are chalcone, substituted chalcones, chalcone derivatives, cyclic enones, while typical donors may be dimethyl, diethyl, dipropyl, diisopropyl, dibutyl, di-tert-butyl and dibenzyl malonates. This review summarizes the most important enantioselective catalysts applied in these types of reactions.

Preparation and Characterization of a Novel Room Temperature Dicationic Ionic Liquid and its Application in the Synthesis of Xanthenediones Under Solvent-Free Conditions

2018 ◽  
Vol 21 (8) ◽  
pp. 602-608 ◽  
Author(s):  
Zainab Ehsani-Nasab ◽  
Ali Ezabadi
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Reaction Times ◽  
Significant Loss ◽  
Solvent Free ◽  
Acidity Function ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Hammett Acidity Function ◽  
Dicationic Ionic Liquid

Aim and Objective: In the present work, 1, 1’-sulfinyldiethylammonium bis (hydrogen sulfate) as a novel room temperature dicationic ionic liquid was synthesized and used as a catalyst for xanthenediones synthesis. Material and Method: The dicationic ionic liquid has been synthesized using ethylamine and thionyl chloride as precursors. Then, by the reaction of [(EtNH2)2SO]Cl2 with H2SO4, [(EtNH2)2SO][HSO4]2 was prepared and after that, it was characterized by FT-IR, 1H NMR, 13C NMR as well as Hammett acidity function. This dicationic ionic liquid was used as a catalyst for the synthesis of xanthenediones via condensation of structurally diverse aldehydes and dimedone under solvent-free conditions. The progress of the reaction was monitored by thin layer chromatography (ethyl acetate/n-hexane = 3/7). Results: An efficient solvent-free method for the synthesis of xanthenediones has been developed in the presence of [(EtNH2)2SO][HSO4]2 as a powerful catalyst with high to excellent yields, and short reaction times. Additionally, recycling studies have demonstrated that the dicationic ionic liquid can be readily recovered and reused at least four times without significant loss of its catalytic activity. Conclusion: This new dicationic ionic liquid can act as a highly efficient catalyst for xanthenediones synthesis under solvent-free conditions.

Nickel (II) and oxovanadium (IV) complexes supported on MCM-41 mesoporous and their application in catalytic selective sulfide and thiol oxidation

2020 ◽  
Vol 23 ◽  
Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Sol Gel ◽  
Reaction Times ◽  
Significant Loss ◽  
Spectral Studies ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Solvent Free Conditions ◽  
Mcm 41

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.

The Impact of Economic Crisis on Tourism Industry: A Bangladesh Perspective

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Md. Ziaul Haque
Keyword(s):  
Economic Crisis ◽  
Tourism Industry ◽  
Political Crisis ◽  
Strong Impact ◽  
Negative Consequences ◽  
Policy Makers ◽  
Tourism Product ◽  
International Tourist ◽  
Sustained Recovery ◽  
The Impact

The tourism sector is experiencing numerous challenges as a result of the global economic crisis. After a significant contraction in 2009, tourism rebounded strongly  in  2010  and  in  2011  the  international  tourist  arrivals  and  receipts  are projected to increase substantially. The Tourism industry is expected to show a sustained recovery in 2012. The crisis has particularly strong impact and slightly negative consequences in Bangladesh. The country is undergoing a political crisis, as well, and it seems that the forthcoming elections may be the only solution for the restoration of stability and social peace.  In addition, tourism can be the driving force behind Bangladesh economic recovery. However, for its achievement the country’s policy makers should take several measures towards restructuring and improving the sector. These measures include: enhancement of alternative forms of tourism; environmental protection; creation of quality infrastructure; and boost of competitiveness through a tourism product that offers value for money

The Impact Of Economic Crisis On Tourism Industry: A Bangladesh Perspective

2015 ◽  
Vol 1 (1) ◽  
pp. 15
Author(s):  
Md. Ziaul Haque
Keyword(s):  
Economic Crisis ◽  
Tourism Industry ◽  
Political Crisis ◽  
Strong Impact ◽  
Negative Consequences ◽  
Policy Makers ◽  
Tourism Product ◽  
International Tourist ◽  
Sustained Recovery ◽  
The Impact

The tourism sector is experiencing numerous challenges as a result of the global economic crisis. After a significant contraction in 2009, tourism rebounded strongly  in  2010  and  in  2011  the  international  tourist  arrivals  and  receipts  are projected to increase substantially. The Tourism industry is expected to show a sustained recovery in 2012. The crisis has particularly strong impact and slightly negative consequences in Bangladesh. The country is undergoing a political crisis, as well, and it seems that the forthcoming elections may be the only solution for the restoration of stability and social peace.  In addition, tourism can be the driving force behind Bangladesh economic recovery. However, for its achievement the country’s policy makers should take several measures towards restructuring and improving the sector. These measures include: enhancement of alternative forms of tourism; environmental protection; creation of quality infrastructure; and boost of competitiveness through a tourism product that offers value for money

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