Time filter

Source Type

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

A palladium-catalysed aminocarbonylation of a steroidal iodoalkene (17-iodo-5α-androst-16-ene) model compound with 2,2′-diamino-1,1′-binaphthalene as an N-nucleophile was carried out. The combination of a steroidal skeleton possessing central elements of chirality and a binaphthyl moiety with axial chirality was carried out resulting in a novel type of steroidal carboxamides. The binaphthalene - steroid conjugates are potential 5α-reductase inhibitors. Both epimers of the monocarboxamide and those of the dicarboxamide, formed with moderate diastereoselectivity, were isolated and fully characterised. © 2014 Elsevier Ltd. All rights reserved. Source

Kiss M.,University of Pecs | Palinkas N.,University of Pecs | Takacs A.,University of Pecs | Maho S.,Gedeon Richter Pharmaceutical Works | And 2 more authors.

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. Source

Nagymihaly Z.,University of Pecs | Kollar L.,University of Pecs | Kollar L.,MTA PTE Research Group for Selective Chemical Syntheses

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. Source

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

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. Source

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

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. Source

Discover hidden collaborations