scholarly journals Microwaves as “Co-Catalysts” or as Substitute for Catalysts in Organophosphorus Chemistry

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1196
Author(s):  
György Keglevich
Keyword(s):  
Coupling Reaction ◽  
Diels Alder ◽  
Typical Case ◽  
Conventional Heating ◽  
Phosphine Oxides ◽  
Phosphonic Acids ◽  
Co Catalysts ◽  
Mw Irradiation ◽  
Organophosphorus Chemistry ◽  
Hydrolysis Of

The purpose of this review is to summarize the importance of microwave (MW) irradiation as a kind of catalyst in organophosphorus chemistry. Slow or reluctant reactions, such as the Diels-Alder cycloaddition or an inverse-Wittig type reaction, may be performed efficiently under MW irradiation. The direct esterification of phosphinic and phosphonic acids, which is practically impossible on conventional heating, may be realized under MW conditions. Ionic liquid additives may promote further esterifications. The opposite reaction, the hydrolysis of P-esters, has also relevance among the MW-assisted transformations. A typical case is when the catalysts are substituted by MWs, which is exemplified by the reduction of phosphine oxides, and by the Kabachnik–Fields condensation affording α-aminophosphonic derivatives. Finally, the Hirao P–C coupling reaction may serve as an example, when the catalyst may be simplified under MW conditions. All of the examples discussed fulfill the expectations of green chemistry.

Microwave irradiation and catalysis in organophosphorus reactions

2019 ◽  
Vol 91 (1) ◽  
pp. 145-157 ◽  
Author(s):  
György Keglevich ◽  
Nóra Zsuzsa Kiss ◽  
Réka Henyecz ◽  
Zoltán Mucsi
Keyword(s):  
Microwave Irradiation ◽  
Aryl Halides ◽  
Arbuzov Reaction ◽  
Phosphine Oxides ◽  
Direct Esterification ◽  
Phosphinic Acids ◽  
Mw Irradiation ◽  
Organophosphorus Chemistry ◽  
Active Methylene ◽  
The Arbuzov Reaction

AbstractThe usual advantage of microwave (MW) assistance is making organic reactions faster and more efficient. In this article we present reaction types from organophosphorus chemistry, when MW-assisted transformations (e.g. the direct esterification and alkylating esterification of phosphinic acids) may be promoted by suitable catalysts, or vice versa, when a catalytic reaction is enhanced by MW irradiation (e.g. the Arbuzov reaction of aryl halides), and when catalysts may be omitted or simplified under MW irradiation as shown by the alkylation of active methylene containing P=O substrates/the Kabachnik–Fields reaction/deoxygenation of phosphine oxides, and the Hirao reaction, respectively.

Newer Developments in the Synthesis of P-Heterocycles

2019 ◽  
Vol 23 (12) ◽  
pp. 1342-1355 ◽  
Author(s):  
György Keglevich
Keyword(s):  
Phosphine Oxides ◽  
Heterocyclic Chemistry ◽  
Enhancing Effect ◽  
Direct Esterification ◽  
Ring Enlargement ◽  
Special Part ◽  
User Friendly ◽  
Ring Species ◽  
Organophosphorus Chemistry ◽  
Hydrolysis Of

The P-heterocyclic field forms a special part of organophosphorus chemistry, and is a special discipline within heterocyclic chemistry. The relevant results accumulated in the group of the author of this minireview in last 5 years are summarized. After surveying the conformational situation of cyclic phosphinates, their Microwave (MW)-assisted direct esterification and the T3P®-promoted esterification are discussed. The next chapters describe newer results regarding the interpretation and modelling of the rate enhancing effect of MWs, and on an important, but somewhat neglected field, the hydrolysis of phosphinates. New results on the ring enlargement of 5-membered unsaturated P-heterocycles to 6-ring species, as well as on the synthesis of 7-phosphanorbornene derivatives, and their refunctionalization are also included. Novel findings on the preparation of cyclic amides and imides are also explored. Last but not least, the user-friendly deoxygenations of cyclic phosphine oxides elaborated by us are shown. The reader will be able to discover green chemical considerations and accomplishments throughout the series of organophosphorus transformations reviewed.

Polar Diels-Alder Reactions Under Microwave Irradiation Employing Different Heterocyclic Compounds as Electrophiles

2019 ◽  
Vol 16 (6) ◽  
pp. 527-543 ◽  
Author(s):  
Pedro M.E. Mancini ◽  
Carla M. Ormachea ◽  
María N. Kneeteman
Keyword(s):  
Organic Synthesis ◽  
Heterocyclic Compounds ◽  
Ionic Conduction ◽  
Theoretical Calculations ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
The Other ◽  
Conventional Heating ◽  
Protic Ionic Liquids ◽  
Solvent Free Conditions

During the last twenty years, our research group has been working with aromatic nitrosubstituted compounds acting as electrophiles in Polar Diels-Alder (P-DA) reactions with different dienes of diverse nucleophilicity. In this type of reaction, after the cycloaddition reaction, the nitrated compounds obtained as the [4+2] cycloadducts suffer cis-extrusion with the loss of nitrous acid and a subsequent aromatization. In this form, the reaction results are irreversible. On the other hand, the microwave-assisted controlled heating become a powerful tool in organic synthesis as it makes the reaction mixture undergo heating by a combination of thermal effects, dipolar polarization and ionic conduction. As the Diels-Alder (D-A) reaction is one of the most important process in organic synthesis, the microwave (MW) irradiation was applied instead of conventional heating, and this resulted in better yields and shorter reaction times. Several substituted heterocyclic compounds were used as electrophiles and different dienes as nucleophiles. Two experimental situations are involved: one in the presence of Protic Ionic Liquids (PILs) as solvent and the other under solvent-free conditions. The analysis is based on experimental data and theoretical calculations.

scholarly journals MW irradiation and ionic liquids as green tools in hydrolyses and alcoholyses

2020 ◽  
Vol 10 (1) ◽  
pp. 001-010 ◽  
Author(s):  
Nikoletta Harsági ◽  
Betti Szőllősi ◽  
Nóra Zsuzsa Kiss ◽  
György Keglevich
Keyword(s):  
Ionic Liquids ◽  
Alkaline Hydrolysis ◽  
Alkyl Group ◽  
Phosphinic Acid ◽  
Reaction Times ◽  
Alternative Possibility ◽  
First Order ◽  
Pseudo First Order ◽  
Mw Irradiation ◽  
Hydrolysis Of

Abstract The optimized HCl-catalyzed hydrolysis of alkyl diphenylphosphinates is described. The reaction times and pseudo-first-order rate constants suggested the iPr > Me > Et ∼ Pr ∼ Bu order of reactivity in respect of the alkyl group of the phosphinates. The MW-assisted p-toluenesulfonic acid (PTSA)-catalyzed variation means a better alternative possibility due to the shorter reaction times, and the alkaline hydrolysis is another option. The transesterification of alkyl diphenylphosphinates took place only in the presence of suitable ionic liquids, such as butyl-methylimidazolium hexafluorophosphorate ([bmim][PF6]) and butyl-methylimidazolium tetrafluoroborate ([bmim][BF4]). The application of ethyl-methylimidazolium hydrosulfate ([emim][HSO4]) and butyl-methylimidazolium chloride ([bmim][Cl]) was not too efficient, as the formation of the ester was accompanied by the fission of the O–C bond resulting in the formation of Ph2P(O)OH. This surprising transformation may be utilized in the phosphinate → phosphinic acid conversion.

Microwave-assisted hydrolysis of phosphonate diesters: an efficient protocol for the preparation of phosphonic acids

2012 ◽  
Vol 14 (8) ◽  
pp. 2282 ◽  
Author(s):  
Petr Jansa ◽  
Ondřej Baszczyňski ◽  
Eliška Procházková ◽  
Martin Dračínský ◽  
Zlatko Janeba
Keyword(s):  
Phosphonic Acids ◽  
Microwave Assisted ◽  
Hydrolysis Of

A synthesis and some reactions of 7-Oxabicyclo[2.2.1]heptan-2-one

1983 ◽  
Vol 36 (12) ◽  
pp. 2473 ◽  
Author(s):  
J Moursounidis ◽  
D Wege
Keyword(s):  
Thermal Decomposition ◽  
Alder Reaction ◽  
Diels Alder ◽  
Acid Mixture ◽  
Diels Alder Reaction ◽  
Reaction Proceeds ◽  
Atom Migration ◽  
Acyl Azide ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Diels-Alder reaction between furan and α-chloroacrylonitrile gives a mixture of exo-2-chloro-and endo-2-chloro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitrile (4) and (5). Mild hydrolysis affords the corresponding α-chloro acid mixture, from which the endo carboxylic acid may be removed through iodo lactone formation. Catalytic hydrogenation of (4) and (5) followed by hydrolysis, acyl azide formation, Curtius rearrangement, and hydrolysis of the resulting mixture of a-chloro isocyanates yields 7-oxabicyclo[2.2.l]heptan-2-one (1) in preparatively useful amounts. Reduction of (1) gives only endo alcohol, and Baeyer-Villiger reaction proceeds with exclusive bridgehead atom migration. Thermal decomposition of the sodium salt of the p-toluenesulfonylhydrazone of (1) affords 7-oxatricyclo[2.2.1 .02,6]heptane.

Synthesis and Application of Tetrafluoroethylene (CF2CF2)-Containing Acetylene Derivatives

Synthesis ◽  
2020 ◽  
Vol 52 (13) ◽  
pp. 1947-1958
Author(s):  
Tsutomu Konno ◽  
Gen Egashira ◽  
Chihiro Kajimoto ◽  
Takuto Kataoka ◽  
Shigeyuki Yamada
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Alder Reaction ◽  
Diels Alder ◽  
Benzene Derivatives ◽  
Diels Alder Reaction ◽  
Cross Coupling Reaction ◽  
Oxidative Aromatization ◽  
High Yields ◽  
Acetylene Derivatives

On treating 1,3,4-tribromo-1,1,2,2-tetrafluorobutane, readily prepared from commercially available 4-bromo-3,3,4,4-tetrafluorobut-1-ene, with 3.3 equivalents of LHMDS at 0 °C in THF, the corresponding lithium acetylide could be prepared quantitatively. The acetylide reacted well with various aldehydes, ketones, or chlorosilanes to give the corresponding acetylene derivatives in high yields. It was also found that various iodoarenes could participate in the cross-coupling reaction with the zinc acetylide, readily prepared from the lithium acetylide and ZnCl2·TMEDA complex, in the presence of Pd(PPh3)4 to bring about the adducts in high yields. Thus-obtained acetylene derivatives underwent smooth Diels–Alder reaction with various 1,3-dienes to afford the corresponding 1,4- or 1,3-cyclohexadiene derivatives. In addition, it was revealed that the oxidative aromatization of the resulting cyclohexadiene derivatives with DDQ took place very smoothly, providing the multi-substituted benzene derivatives having a tetrafluoro­ethylene group.

Tandem dihetero-Diels–Alder and Huisgen cycloaddition reactions. Synthesis, crystal structure and hydrolysis of the novel cage phosphoranes

2018 ◽  
Vol 5 (21) ◽  
pp. 3113-3128 ◽  
Author(s):  
Nadezhda R. Khasiyatullina ◽  
Tamara A. Baronova ◽  
Ekaterina V. Mironova ◽  
Robert R. Fayzullin ◽  
Igor A. Litvinov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Carbonyl Compounds ◽  
Diels Alder ◽  
Cycloaddition Reactions ◽  
The Novel ◽  
Hydrolysis Of

The reaction of 2-(1-phenylvinyloxy)benzo-1,3,2-dioxaphosphole with activated carbonyl compounds leads to the stereoselective formation of cage phosphoranes.

Synthesis of endo-fused 5-unsubstituted hexahydro-2H-pyrano[3,2- c]quinolines via sequential Sc(OTf)3-catalyzed cationic imino-Diels-Alder Reaction/N-debenzylation using N-benzylanilines, 3,4-dihydro-2H-pyran and paraformaldehyde under MW irradiation

2021 ◽  
Vol 18 ◽  
Author(s):  
Arturo René Mendoza Salgado ◽  
Carlos Eduardo Puerto Galvis ◽  
Vladimir V. Kouznetsov ◽  
Carlos Mario Meléndez
Keyword(s):  
Efficient Method ◽  
Cycloaddition Reaction ◽  
Acid Catalyst ◽  
Alder Reaction ◽  
Diels Alder ◽  
Synthetic Methods ◽  
Diels Alder Reaction ◽  
Catalytic Transfer ◽  
Lewis Acid Catalyst ◽  
Mw Irradiation

Background: Hexahydro-2H-pyrano[3,2-c]quinolines are known to have antibacterial, antifungal, and antitumor properties. Great efforts have been made to develop new synthetic methods that lead to the synthesis of valuable libraries. Extensive methodologies, low yields, excessive amounts of catalyst and expensive reactants are some of the limitations of current methodologies. Aim and Objective: Developing a useful and efficient method to construct diversely substituted hexahydro-2H-pyrano[3,2- c]quinolines into good to excellent yields through a cationic imino-Diels-Alder/N-debenzylation methodology. Method: The cationic imino-Diels-Alder/N-debenzylation methodology was used for the preparation of substituted hexahydro-2H-pyrano[3,2-c]quinolines. It involves the use of Sc(OTf)3 for activation of cationic imino-Diels-Alder cycloaddition reaction of N-benzylanilines, 3,4-dihydro-2H-pyran and paraformaldehyde in MeCN; and microwave irradiation to shorten reaction time to afford new 6-benzyl-hexahydro-2H-pyrano[3,2-c]quinolines whose catalytic transfer debenzylation reactions with HCO2NH4 in the presence of Pd/C (10%) and methanol give the new 5-unsubstituted pyrano[3,2- c]quinolines in excellent yields. Results: We found that optimal conditions for the preparation of hexahydro-2H-pyrano[3,2-c]quinolines were Sc(OTf)3 0,5 % and acetonitrile at 160 ° C for 15 min; and using paraformaldehyde obtained the 6-benzyl-hexahydro-2H-pyrano [3,2- c]quinolines with excellent yields, while the N-debenzylation process using ammonium formate in the presence of Pd/C and methanol resulted in the synthesis of hexahydro-2H-pyrano [3,2-c] quinolines with quantitative yields (95-98%). Conclusion: We describe an efficient method to synthesize hexahydro-2H-pyrano[3,2-c]quinolines via the cationic iminoDiels-Alder/N-debenzylation methodology using Sc(OTf)3 0,5 % as Lewis Acid catalyst. Excellent yields of the products, using of MW irradiation, short times of reactions and an efficient and highly diversified method are some of the main advantages of this new protocol.

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