Vanadium-catalyzed, microwave-assisted oxidations with H2O2 in ionic liquids

2009 ◽  
Vol 81 (7) ◽  
pp. 1265-1277 ◽  
Author(s):  
Valeria Conte ◽  
Francesca Fabbianesi ◽  
Barbara Floris ◽  
Pierluca Galloni ◽  
Daniela Sordi ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Functional Groups ◽  
Efficient Procedure ◽  
Microwave Assisted ◽  
Study Results ◽  
Rate Of Reaction ◽  
Vanadium Based Catalysts ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Epoxidation Of Alkenes

The application of vanadium(V) catalysts in selective oxidation with peroxides offers an efficient procedure that is compatible with different functional groups and leads to good yields and selectivities. However, the search for more efficient and sustainable procedures that employ H2O2 as oxidant remains an important topic. In the last few years, striking results have been obtained by applying microwave (MW) activation in metal-catalyzed reactions carried out in ionic liquids (ILs). In the present study, results achieved with vanadium-based catalysts in oxidations of various substrates with H2O2 are presented; in particular, epoxidation of alkenes and sulfoxidation of thioethers have been investigated. Notably, in the latter oxidation, a significant improvement in the rate of reaction and an increase in selectivity have been observed in the case of hydrophobic ILs in combination with MW activation.

Ionic Liquid Promoted Eco-friendly and Efficient Synthesis of Six-membered Npolyheterocycles

2018 ◽  
Vol 15 (8) ◽  
pp. 1124-1146 ◽  
Author(s):  
Navjeet Kaur
Keyword(s):  
Organic Chemistry ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Organic Solvents ◽  
Review Article ◽  
Environmentally Benign ◽  
Wide Range ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Reaction Media

Background: The synthesis of N-polyheterocycles by environmentally benign method is highly attractive but challenging proposition. New strategies have been developed for the preparation of polycyclic heterocycles in the last decades. In this review article, the synthesis of nitrogen containing six-membered polycyclic heterocyclic compounds is presented with the application of ionic liquids. This contribution focuses on the literature related to the total synthesis of six-membered N-polyheterocycles. Objective: Ionic liquids not only acted as environmentally benign reaction media but also as catalysts which afforded the very promising replacements of traditional molecular solvents in organic chemistry due to their stability, non-flammability, non-volatility and ease of recyclability. Ionic liquids are utilized in metal catalyzed reactions in place of organic solvents in the last years. It has attracted considerable attention in recent years. Ionic liquids acted as alternatives of organic solvents and these ILs are environment friendly. Conclusion: In the area of green chemistry ionic liquid assisted synthesis is a very promising technique which afforded a flexible platform for the formation of heterocycles. The influence of ILs on the development of efficient and new synthetic protocols over the last decade for the construction of N-polyheterocycles is featured in this review article. These synthetic strategies will continue to attract more attention and will find a wide range of applications in organic synthesis. In conclusion, ionic liquids assisted syntheses have become an efficient and powerful tool in organic chemistry quickly.

scholarly journals Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction

2019 ◽  
Vol 15 ◽  
pp. 679-684 ◽  
Author(s):  
Vaida Milišiūnaitė ◽  
Rūta Paulavičiūtė ◽  
Eglė Arbačiauskienė ◽  
Vytas Martynaitis ◽  
Wolfgang Holzer ◽  
...  
Keyword(s):  
Pyrazole Ring ◽  
Ring System ◽  
Ring Closure ◽  
X Ray Diffraction ◽  
Efficient Procedure ◽  
Ring Systems ◽  
X Ray ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Derivatives Of

Fused pyrazole ring systems are common structural motifs of numerous pharmaceutically important compounds. Nevertheless, access to derivatives of the aromatic 2H-furo[2,3-c]pyrazole ring system is still quite limited, and their chemistry and functional properties remain largely underexplored. The current study investigates routes to construct this system from easily accessible starting materials using metal-catalyzed reactions. A simple and efficient procedure to access the 2H-furo[2,3-c]pyrazole ring system was developed by employing the silver(I) ion-mediated ring-closure reaction of 4-alkynyl-3-hydroxy-1-phenyl-1H-pyrazoles as a key step. The required intermediate hydroxyalkynyl substrates for this reaction were prepared by a Pd-catalyzed coupling of 4-iodo-1-phenyl-1H-pyrazol-3-ol with ethyne derivatives. The structures of the obtained target compounds were unequivocally confirmed by detailed 1H, 13C and 15N NMR spectroscopic experiments, HRMS and a single-crystal X-ray diffraction analyses. This silver(I)-mediated 5-endo-dig cyclization of readily available 4-alkynyl-3-hydroxy-1H-pyrazoles can be used as an efficient method to access many novel 2,5-disubstituted 2H-furo[2,3-c]pyrazoles.

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.

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

2021 ◽  
Vol 17 ◽  
Author(s):  
Austin Pounder ◽  
Angel Ho ◽  
Matthew Macleod ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Substituent Effects ◽  
Face Selectivity ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

scholarly journals Transition metal-catalyzed reactions of N-sulfinyl imines

2021 ◽  
pp. 153104
Author(s):  
Francisco Foubelo ◽  
Carmen Nájera ◽  
José M. Sansano ◽  
Miguel Yus
Keyword(s):  
Transition Metal ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

scholarly journals Cycloaddition of Thiourea- and Guanidine-Substituted Furans to Dienophiles: A Comparison of the Environmentally-Friendly Methods

2020 ◽  
Vol 3 (1) ◽  
pp. 57
Author(s):  
Luka Barešić ◽  
Davor Margetić ◽  
Zoran Glasovac
Keyword(s):  
High Pressure ◽  
Functional Groups ◽  
Organic Synthesis ◽  
High Speed ◽  
Environmentally Friendly ◽  
Microwave Assisted ◽  
Pressure Synthesis ◽  
Ultrasound Assisted ◽  
Substituted Furans ◽  
Guanidine Moiety

The cycloaddition strategy was employed in order to obtain a 7-oxanorbornene framework substituted with a guanidine moiety or its precursor functional groups: protected amine or thiourea. In order to optimize the conditions for the cycloaddition, several environmentally-friendly methods—microwave assisted organic synthesis, high pressure synthesis, high speed vibrational milling, and ultrasound assisted synthesis—were employed. The outcomes of the cycloaddition reactions were interpreted in terms of endo/exo selectivity, the conversion of the reactants to the product, and the isolated yields. In general, our results indicated the HP and HSVM approaches as the methods of choice to give good yields and conversions.

scholarly journals Chiral Aziridine Sulfide N(sp3),S-Ligands for Metal-Catalyzed Asymmetric Reactions

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 502
Author(s):  
Agata J. Pacuła-Miszewska ◽  
Anna Laskowska ◽  
Anna Kmieciak ◽  
Mariola Zielińska-Błajet ◽  
Marek P. Krzemiński ◽  
...  
Keyword(s):  
Metal Binding ◽  
Electronic Effect ◽  
Asymmetric Reactions ◽  
Addition Reactions ◽  
Phenyl Sulfide ◽  
Enantiomeric Ratio ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Sulfide Group

A series of new bidentate N,S-ligands—aziridines containing a para-substituted phenyl sulfide group—was synthesized and evaluated in the Pd-catalyzed Tsuji–Trost reaction and addition of diethylzinc and phenylethynylzinc to benzaldehyde. A high enantiomeric ratio for the addition reactions (up to 94.2:5.8) was obtained using the aziridine ligand bearing a p-nitro phenyl sulfide group. Collected results reveal a specific electronic effect that, by the presence of particular electron-donating or electron-withdrawing groups in the PhS- moiety, influences the σ-donor–metal binding and the enantioselectivity of the catalyzed reactions.

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