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Keglevich A.,Budapest University of Technology and Economics | Hegedus L.,Budapest University of Technology and Economics | Peter L.,Budapest University of Technology and Economics | Gyenese J.,Budapest University of Technology and Economics | And 11 more authors.
Current Organic Chemistry | Year: 2016

Halogenation reactions of vindoline and 14,15-dihydrovindoline and its hydrochloric salt were investigated and the anomalous reductions were discussed. Performing the hydrogenation in the presence of chlorine-containing solvent, e.g. dichloromethane, hydrogenolysation reaction of chlorine also took place. In this case unexpected chlorinated product could be observed. Performing the hydrogenation reaction only in the presence of methanol, the expected reduced derivative was obtained. Upon bromination of vindoline with excess NBS, oxidation products with ring contraction and developing an oxygen bridge were isolated. The fluorination reactions of vinblastine using Selectfluor® and xenon difluoride as the fluorination reagents were unsuccessful because of the decomposition of the starting material. Reactions of vindoline with Selectfluor® a mixture of products were obtained. Using xenon difluoride as fluorination agent resulted in a pure quinoidal product containing the fluorine atom in the bridgehead carbon atom of the indole ring. The fluorination of catharanthine gave an anomalous indolenine type product. © 2016 Bentham Science Publishers.


Szekely G.,Budapest University of Technology and Economics | Csordas B.,Eötvös Loránd University | Farkas V.,Eötvös Loránd University | Kupai J.,Budapest University of Technology and Economics | And 9 more authors.
European Journal of Organic Chemistry | Year: 2012

New enantiopure crown ethers containing either an ethyl diarylphosphinate moiety [(S,S)-4 to (S,S)-7] or a proton-ionizable diarylphosphinic acid unit [(S,S)-8 to (S,S)-11] have been synthesized. Electronic circular dichroism (ECD) studies on the complexation of these new enantiopure crown ethers with the enantiomers of α-(1-naphthyl)ethylammonium perchlorate (1-NEA) and with α-(2-naphthyl)ethylammonium perchlorate (2-NEA) were also carried out. These studies showed appreciable enantiomeric recognition with heterochiral [(S,S)-crown ether plus either (R)-1- or (R)-2-NEA] preference. Theoretical calculations found three significant intermolecular hydrogen bonds in the complexes of (S,S)-9. Furthermore, preference for heterochiral complexes was also observed, in good agreement with ECD results. Complex formation constants were determined by NMR titration for four selected crown ether/NEA pairs. Enantiopure crown ethers containing either an ethyl phosphinate [(S,S)-4 to (S,S)-7] or a phosphinic acid moiety [(S,S)-8 to (S,S)-11] were synthesized and complexation with the enantiomers of 1- and 2-NEA was studied. Calculations showed three important hydrogen bonds between (S,S)-9 and each enantiomer of 1-NEA and 2-NEA. Appreciable enantiomeric recognition and heterochiral preference were found. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Keglevich P.,Budapest University of Technology and Economics | Abranyi-Balogh P.,Hungarian Academy of Sciences | Szigetvari A.,Spectroscopic Research Division | Szantay C.,Spectroscopic Research Division | And 2 more authors.
Tetrahedron Letters | Year: 2016

A quaternization reaction was observed at the tertiary nitrogen atom of the catharanthine part of vinblastine instead of the expected cyclopropanation in the Simmons-Smith reaction utilizing diiodomethane and diethylzinc. Investigating the energetic relations, thermodynamic stabilities and the interactions between the molecular orbitals by quantum chemical calculations elucidated the unexpected methylation and confirmed the reaction mechanism. Although the history of the Simmons-Smith reaction goes back more than half a century this represents the first time that the reaction and its possible side-reaction has been studied by DFT level calculations in a complex system. © 2016 Elsevier Ltd.


Keglevich P.,Budapest University of Technology and Economics | Kovacs P.,Hungarian Academy of Sciences | Hazai L.,Hungarian Academy of Sciences | Santa Z.,Spectroscopic Research Division | And 6 more authors.
Heterocycles | Year: 2012

In the course of the reaction between galanthamine and diazomethane in the presence of a catalyst, such as palladium(II) acetate or copper(I) bromide, methylene insertion into the aromatic ring was observed instead of the expected cyclopropanation of the carbon-carbon double bond. © 2012 The Japan Institute of Heterocyclic Chemistry.


Herke K.,Budapest University of Technology and Economics | Hazai L.,Hungarian Academy of Sciences | Dubrovay Z.,Spectroscopic Research Division | Hada V.,Spectroscopic Research Division | And 5 more authors.
Heterocycles | Year: 2011

Demethoxy-lycoraminone (8) was prepared in several steps starting from the appropriate benzo[c]azepine dione derivative (9). Ketone (9) was protected as a ketal group followed by methylation on the azepine nitrogen atom. After reduction of the imide carbonyl groups, deprotection, demethylation and ring closure were carried out as a one-pot reaction in methanesulfonic acid in the presence of racemic methionine. © The Japan Institute of Heterocyclic Chemistry.


Szantay C.,Budapest University of Technology and Economics | Keglevich P.,Budapest University of Technology and Economics | Hazai L.,Budapest University of Technology and Economics | Gorka-Kereskenyi A.,Budapest University of Technology and Economics | And 9 more authors.
Heterocycles | Year: 2013

10-Bromovindoline and its 14,15-dihydro- and 14,15-cyclopropano derivatives were coupled in the position 16 with (L)- and (D)-tryptophan methyl esters. The tryptophan derivatives of vindoline were synthesized starting from the 16-carboxylic acid hydrazides via the corresponding azides which were allowed to react with the amino acid esters. The new compounds showed antitumor activity against human leukemia (HL-60) cells in vitro. © 2013 The Japan Institute of Heterocyclic Chemistry.


Herke K.,Budapest University of Technology and Economics | Hazai L.,Hungarian Academy of Sciences | Santa Z.,Spectroscopic Research Division | Dubrovay Z.,Spectroscopic Research Division | And 5 more authors.
Tetrahedron Letters | Year: 2010

Attempted cyclisation of N-methylated spiro benzazepine-cyclohexenone (5) into the corresponding Nmethyl tetracyclic unit of galanthamine-type alkaloids (6) instead gave an unexpected rearrangement to yield a cyclopentanoisoquinolinone derivative (7). Methylation of the tetrahydrobenzofurobenzazepine tetracycle resulted in the expected N-methyl derivative 6, and the anomalous product 8, with structure similar to that of 7. © 2010 Elsevier Ltd. All rights reserved.


Ilkei V.,Budapest University of Technology and Economics | Bana P.,Budapest University of Technology and Economics | Toth F.,XiMo Hungary Ltd. | Pallo A.,Hungarian Academy of Sciences | And 9 more authors.
Tetrahedron | Year: 2015

Bannucine is an Aspidosperma alkaloid isolated from the dried leaves of Catharanthus roseus. The molecule is a derivative of vindoline bearing a C10 substituent, a pattern common to the antineoplastic dimeric indole alkaloids of C. roseus. In bannucine, a 2-pyrrolidone moiety is attached at C5′ to the aromatic ring of the vindoline core at C10. In the present work we report the synthesis of bannucine and its 5′-epimer from natural (-)-vindoline using a cyclic N-acyliminium ion intermediate whose N-acylaminocarbinol precursor is synthesized by the partial reduction of succinimide. We also describe the separation and the structural analysis of the two epimers, using among others, single crystal X-ray diffraction methods, in order to clarify the orientation of the proton attached to the C5′ carbon. The in vitro antineoplastic activity of the pure epimers was also investigated, but none of the two substances showed significant activity on the examined tumour cell lines. © 2015 Published by Elsevier Ltd.


Keglevich P.,Budapest University of Technology and Economics | Hazai L.,Budapest University of Technology and Economics | Dubrovay Z.,Spectroscopic Research Division | Santa Z.,Spectroscopic Research Division | And 4 more authors.
Heterocycles | Year: 2015

Vinorelbine condensed with a cyclopropane ring in the position 14 and 15 of the vindoline monomer part was synthesized and was found to have excellent antitumor activity. Further derivatives of cyclopropano-vinorelbine were prepared, the vincristine-like derivative, the N1-formyl-cyclopropano-vinorelbine, and the hydrated vinorelbine analogue, i.e. 5'-desmethylene-cyclopropanovinblastine. © 2015 The Japan Institute of Heterocyclic Chemistry.


Keglevich P.,Budapest University of Technology and Economics | Hazai L.,Budapest University of Technology and Economics | Dubrovay Z.,Spectroscopic Research Division | Dekany M.,Spectroscopic Research Division | And 3 more authors.
Heterocycles | Year: 2014

A new type of vinblastine and vincristine derivatives was synthesized. The carbon carbon double bond in position 14 and 15 of the vindoline ring was cyclopropanated. In the course of the synthetic work 14,15-cyclopropanovindoline was coupled with catharanthine, resulting in the cyclopropanated anhydrovinblastine as a key intermediate to 14,15-cyclopropano-vinblastine and - vincristine. © 2014 The Japan Institute of Heterocyclic Chemistry.

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