MTA PTE Research Group for Selective Chemical Syntheses

Pécs, Hungary

MTA PTE Research Group for Selective Chemical Syntheses

Pécs, Hungary
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Pongracz P.,University of Pécs | Kollar L.,University of Pécs | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses
Journal of Heterocyclic Chemistry | Year: 2017

A chiral cyclic carbonate, 4-vinyl-1,3-dioxolan-2-one was used as racemic substrate in asymmetric hydroformylation. The catalysts were formed in situ from “pre-formed” PtCl2(diphosphine) and tin(II) chloride. (2S,4S)-2,4-Bis(diphenylphosphinopentane ((S,S)-BDPP)), (S,S)-2,3-O-izopropylidine-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane ((S,S)-DIOP)), and (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl ((R)-BINAP)) were used as optically active diphosphine ligands. The platinum-containing catalytic systems provided surprisingly high activity. The hydroformylation selectivities of up to 97% were accompanied by perfect regioselectivity towards the dioxolane-based linear aldehyde. The enantiomeric composition of all components in the reaction mixture was determined and followed throughout the reaction. The unreacted 4-vinyl-1,3-dioxolan-2-one was recovered in optically active form. The kinetic resolution was rationalized using the enantiomeric composition of the substrate and the products. © 2016 Wiley Periodicals, Inc.

Kiss M.,University of Pécs | Palinkas N.,University of Pécs | Takacs A.,University of Pécs | Maho S.,Gedeon Richter Pharmaceutical Works | And 2 more authors.
Steroids | Year: 2013

3,17-Dicarboxamido-androst-3,5,16-triene derivatives possessing various amine moieties were synthesized under mild conditions using palladium-catalyzed homogeneous aminocarbonylation as key reaction. Compounds containing the corresponding iodoalkene functionalities, i.e., 17-iodo-16-ene and 3-iodo-3,5-diene structural motifs, were used in the aminocarbonylation and the N-nucleophiles were varied systematically. Three amines, such as tert-butylamine, piperidine and methyl alaninate were used as N-nucleophiles in the aminocarbonylation. All variations of 3,17-dicarboxamides were synthesized using this methodology. Androst-4-ene-3,17-dione was used as starting material. The synthetic strategy of the multistep synthesis was based on the systematic variation and consecutive use of three different reactions: (i) the protection/deprotection of one of the keto functionalities (3-one or 17-one) as ethylene ketals, (ii) the transformation of the other keto group to iodoalkene functionality via its hydrazone, and (iii) palladium-catalyzed aminocarbonylation of the iodoalkene functionality. © 2013 Elsevier Ltd. All rights reserved.

Pongracz P.,University of Pécs | Kostas I.D.,National Hellenic Research Foundation | Kollar L.,University of Pécs | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses
Journal of Organometallic Chemistry | Year: 2013

Neutral complexes of the formula PtCl2(L) (where L = ortho-diphenylphosphino-N-(2-hydroxyethyl)-N-methylaniline (1), ortho-diphenylphosphino-N-2-(diphenylphoshinoxy)-ethyl)-N-methylaniline (2) and N,N-bis(2-(diphenylphoshinoxy)ethyl)aniline (3)) were prepared. Various binding modes, such as P,N- and P,P-bidentate and monodentate coordinations were observed with these hemilabile ligands in the parent complexes and in the triphenylphosphine-added systems. 31P NMR studies on the 'in situ' systems revealed the hemilabile character of the ligands. The platinum complexes proved to be precursors to catalysts of low activity for the hydroformylation of styrene in platinum-ligand (1, 2 or 3)-tin(II) chloride system. High chemoselectivities (up to 82%) were obtained, while the two aldehyde regioisomers were formed in almost equimolar ratio with the slight preference of the branched aldehyde, 2-phenylpropanal. Remarkable increase in regioselectivity was observed in the presence of para-toluenesulfonic acid additive using platinum-ligand (1) systems. © 2012 Elsevier B.V. All rights reserved.

Papp T.,University of Pécs | Papp T.,Janos Szentagothai Research Center | Kollar L.,University of Pécs | Kollar L.,Janos Szentagothai Research Center | And 4 more authors.
Chemical Physics Letters | Year: 2013

The Hammett para constant (σ of the acetoxy group has been estimated by applying widely available quantum chemical descriptors, such as NPA charges, Wiberg bond indices, electron densities at bond critical points, as well as electrostatic potential at nuclei. The revised σvalue is predicted to be in the range of [-0.08,-0.02]. Direct evaluation of proton transfer free energies between the substituted benzoic acids and the benzoate anion by employing the SMD solvation model resulted in a reasonable linear correlation with the Hammett constants with a prediction of σ= -0.02 for the OAc group. © 2013 Elsevier B.V. All rights reserved.

Mikle G.,University of Pécs | Boros B.,University of Pécs | Kollar L.,University of Pécs | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses
Tetrahedron Asymmetry | Year: 2016

Palladium-catalysed aminocarbonylation of a terpenoic iodoalkene (2-iodo-bornene) model compound with both enantiomerically pure and racemic 2,2'-diamino-1,1'-binaphthalene (BINAM) as the N-nucleophile was carried out. All of the diastereoisomers of the monocarboxamide (N-bornenyl carboxamide) and dicarboxamide (N,. N'-dinorbornenylcarboxamide) derivatives were synthesised. The diastereoselectivities of the aminocarbonylation were investigated in both cases: either racemic BINAM was used as the N-nucleophile in the aminocarbonylation of enantiomerically pure 2-iodobornene or racemic iodobornene was aminocarbonylated with enantiomerically pure BINAM with moderate diastereoselectivities. In this way, all possible diastereoisomers of binaphthalene-bornene conjugates were synthesised in moderate to high yields by asymmetric (diastereoselective) aminocarbonylation. © 2016 Elsevier Ltd.

Carrilho R.M.B.,University of Coimbra | Carrilho R.M.B.,University of Pécs | Pereira M.M.,University of Coimbra | Moreno M.J.S.M.,University of Coimbra | And 4 more authors.
Tetrahedron Letters | Year: 2013

A set of new steroid dimers linked through ring D-ring D were synthesized via catalytic diaminocarbonylation of 17-iodo-5α-androst-16-ene, in the presence of palladium-phosphine in situ catalysts and aliphatic or aromatic diamines as N-nucleophiles. The dimeric steroidal compounds containing 17,17′-dicarboxamide spacers were obtained through highly chemoselective reactions in good isolated yields and completely characterized by spectroscopic techniques. © 2013 Elsevier Ltd.All rights reserved.

Nagymihaly Z.,University of Pécs | Kollar L.,University of Pécs | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses
Tetrahedron | Year: 2015

Conventional high-yielding reactions (such as etherification, condensation reactions) and palladium-catalysed aminocarbonylation served as highly efficient synthetic tools for the synthesis of novel cavitands bearing Schiff-base and carboxamide/2-ketocarboxamide functionalities, respectively. In this way, two families of deepened cavitands with related structures possessing 2-, 3- and 4-picolylamine moieties on the upper rim have been synthesised. Unexpectedly high chemoselectivities towards tetracarboxamides and tetrakis(2-ketocarboxamides) have been observed. The aminocarbonylation of tetraiodocavitand as an iodoaromatic substrate proved to be highly selective in two aspects: (i) no substantial formation of either the mono-, di- or trifunctionalized products was observed and (ii) no 'mixed' products possessing both carboxamide and 2-ketocarboxamide fragments, due to selective simple and double carbon monoxide insertion, were detected. © 2015 Elsevier Ltd. All rights reserved.

Pongracz P.,MTA PTE Research Group for Selective Chemical Syntheses | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses | Kollar L.,University of Pécs
Journal of Organometallic Chemistry | Year: 2016

Two sets of styrenes possessing various substituents either in ortho or para position were hydroformylated in the presence of ‘in situ’ catalyst formed from PtCl2[(R)-BINAP] and tin(II) chloride. The reversal of the absolute configuration of the preferred enantiomers was observed using both sets of substrates by the variation of the reaction temperature in the range of 40–100 °C. In case of the 4-substituted styrenes, the reversal temperature of the enantioselectivity shows correlation with the Hammett substituent constants, i.e., with the electron donor or electron acceptor properties of the para-substituents. This phenomenon was explained by the reversible formation of the Pt-branched alkyl intermediates, leading to the corresponding (R)- and (S)-enantiomers of 2-arylpropanals. Strong substituent effect on the regioselectivity was observed in the hydroformylation of 2-substituted styrenes: the presence of substituents characterised by larger steric parameter resulted in the highly favoured formation of the linear aldehyde. For instance, regioselectivities of 45%, 22% and 7% towards branched aldehyde were obtained with styrene, 2-fluoro- and 2-bromostyrene, respectively, at 80 °C reaction temperature. In addition to the characteristic change of regioselectivity, the reversal of absolute configuration as a function of reaction temperature was also observed. © 2016

Gergely M.,University of Pécs | Farkas R.,University of Pécs | Takacs A.,MTA PTE Research Group for Selective Chemical Syntheses | Petz A.,University of Pécs | And 2 more authors.
Tetrahedron | Year: 2014

A systematic investigation of the palladium-catalysed aminocarbonylation of iodobenzene, 1-iodocyclohexene and 1′-iodostyrene in the presence of N-nucleophiles containing pyridyl moieties (2-, 3- and 4-picolylamine, N-ethyl-4-picolylamine, di-(2-picolyl)amine) was carried out. The two types of iodo substrates differ substantially regarding the selectivity towards carbonylation: while the aminocarbonylation of iodobenzene resulted in the formation of carboxamide and ketocarboxamide mixtures under various conditions, with the predominant formation of ketocarboxamide even at low carbon monoxide pressure, the aminocarbonylation of iodoalkenes under same conditions gave the corresponding unsaturated carboxamide exclusively. Most of the carboxamides and phenylglyoxylamides, obtained via single and double carbon monoxide insertion, respectively, were isolated in yields of synthetic interest (up to 86%). Low reaction rates and unexpected chemoselectivity towards carboxamide formation have been observed with di-(2-picolyl)amine as N-nucleophile in the aminocarbonylation of iodobenzene. © 2013 Elsevier Ltd. All rights reserved.

Farkas R.,University of Pécs | Petz A.,University of Pécs | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses
Monatshefte fur Chemie | Year: 2015

6-(1-Iodovinyl)-1,4-dioxaspiro[4.5]decane, an iodoalkene obtained from 2-acetylcyclohexanone via ethylene ketal formation, hydrazone formation and iodination, was aminocarbonylated in the presence of a palladium-phosphine precatalyst. Systematic investigations revealed that 2-(1,4-dioxaspiro[4.5]decan-6-yl)acrylamides can be obtained in high yields via palladium-catalysed aminocarbonylation. The influence of the amine nucleophiles and of the reaction conditions on the isolated yields was investigated. Graphical abstract: (Chemical Equation Presented). © 2015 Springer-Verlag.

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