Rita Kovács
Budapest University of Technology and Economics
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Featured researches published by Rita Kovács.
Phosphorus Sulfur and Silicon and The Related Elements | 2011
György Kglevich; Alajos Grün; Erika Bálint; Nóra Zs. Kiss; Rita Kovács; István Gábor Molnár; Zsófia Blastik; R. Viola Tóth; András Fehérvári; István Csontos
Abstract A variety of reactions including esterifications, alkylations, additions, cycloadditions, fragmentations, and condensations were carried out under microwave MW-assisted and solventless conditions, occasionally in ionic liquids (ILs). In a few cases, MW was synergic with phase transfer catalysis or could substitute it. A variety of P(III) ligands were developed and converted to Pt(II) complexes that can be used as catalysts. Finally, phosphorylations and the Kabachnik–Fields reaction were monitored and optimized by an on-line method, in situ Fourier transform IR spectroscopy.
Phosphorus Sulfur and Silicon and The Related Elements | 2011
György Keglevich; Rita Kovács; László Drahos
Abstract The effect of the use of microwave (MW) and solvents including ionic liquids on the Diels–Alder reaction of 1,2-dihydrophosphinine oxides (1) and fragmentation-related phosphorylation of phenols with 2-phosphabicyclo[2.2.2]octadiene oxides (4) was studied. The MW-assisted Diels–Alder reaction of dihydrophosphinine oxides (1) with N-phenylmaleimide may be advantageous to carry out in [bmim][BF4] due to shorter reaction times, but the dimerization of the double-bond isomers (A and B) of the dihydrophosphinine oxides (1) may be best accomplished under MW in the absence of any solvent. The fragmentation-related phosphorylations may also be carried out under MW, which with the P-phenyl precursor (4a) became more efficient in [bmim][BF4]. GRAPHICAL ABSTRACT
Phosphorus Sulfur and Silicon and The Related Elements | 2009
György Keglevich; Anna Szekrényi; Rita Kovács; Alajos Grün
Application of the microwave technique offers advantages in organophosphorus chemistry, such as in the Kabachnik–Fields reaction, in Diels–Alder cycloadditions, in an inverse Wittig-type reaction, and in fragmentation-related phosphorylations.
Letters in Drug Design & Discovery | 2013
Rita Kovács; Dávid Illés Nagy; Alajos Grün; György T. Balogh; Sándor Garadnay; István Greiner; György Keglevich
The synthesis of Etidronate (as the disodium salt) by the reaction of acetic acid with phosphorus trichloride/ phosphorus acid in methanesulfonic acid was studied and optimized. We showed that it is enough to use 3.2 equivalents of the phosphorus trichloride and there is no need to apply phosphorus acid. In the two-step variation of the synthesis, the acetyl chloride was formed by the reaction of acetic acid with phosphorus trichloride, thionyl chloride or triphosgene, then the intermediate was converted to etidronate by reaction with 2.2 equivalents of phosphorus trichloride. The work-up included in all cases hydrolysis and pH adjustment.
Phosphorus Sulfur and Silicon and The Related Elements | 2013
György Keglevich; Rita Kovács; Alajos Grün; István Greiner
Abstract Recent results obtained by our group on MW-assisted reactions, such as the alkylation of P˭O-functionalized CH-acidic compounds and the addition of dialkyl phosphites to α-ketophosphonates, are summarized together with the rational synthesis of hydroxy-methylene bis(phosphinic acids). GRAPHICAL ABSTRACT
Phosphorus Sulfur and Silicon and The Related Elements | 2015
György Keglevich; Alajos Grün; Rita Kovács; Sándor Garadnay; István Greiner
GRAPHICAL ABSTRACT Abstract Our recent results on the synthesis of dronates/dronic acids have been summarized.
Phosphorus Sulfur and Silicon and The Related Elements | 2012
Rita Kovács; György T. Balogh; Krisztina Ludányi; László Drahos; György Keglevich
Abstract Under the conditions of transfer hydrogenation by ammonium formate, the title compounds (6) were converted to a mixture of the corresponding 1,2,3,6-tetrahyidrophosphinine oxide (7), its dechlorinated derivative (8) and the respective 1,2,3,4,5,6-hexahydrophosphinine oxide (9). In the phenyl-substituted instance, the ratios of the components depended on the mode of heating (traditional heating or microwave irradiation), temperature, and the solvent (toluene or [bmim][BF4]) used. In the ethoxy-substituted series, the dechlorinated 1,2-dihydrophosphinine oxide (10b) was detected as an intermediate. GRAPHICAL ABSTRACT
Green Processing and Synthesis | 2014
Rita Kovács; Alajos Grün; Sándor Garadnay; István Greiner; György Keglevich
Abstract According to literature, the synthesis of dronic acid derivatives from the corresponding carboxylic acids using phosphorus trichloride and phosphorous acid as the P-reactants is controversial, due to the wide range of molar ratios and diverse conditions. In this minireview, we summarize our results on the clarification of these problems. For example, with zoledronic acid and risedronic acid, we found that, using methanesulfonic acid (MSA) as the solvent, 3.2 equivalents of phosphorus trichloride was enough. Generalizing this optimized method, etidronate, fenidronate, ibandronate and alendronate were obtained in yields of 38%–57%, which is reasonable for valuable dronates, and in most cases, with high purities. Mechanistic aspects are also discussed.
Archive | 2011
György Keglevich; Nóra Zsuzsa Kiss; Erika Bálint; Rita Kovács; Erzsebet Jablonkai; Eszter Fazekas; J. Tóth; A. Kaszás; Zsófia Blastik; Alajos Grün
A variety of reactions including esterifications, alkylations, additions, cycloadditions, fragmentations and condensations were carried out under microwave (MW) and solventless conditions, occasionally in IL-s. In a few cases, the reactions could only be accomplished only under MW conditions, but not on traditional heating. In certain instances, MW could substitute phase transfer catalysis, in other cases MW was synergetic with it.
Heteroatom Chemistry | 2014
Rita Kovács; Alajos Grün; Orsolya Németh; Sándor Garadnay; István Greiner; György Keglevich