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11.
György Keglevich Andrea Kerényi Helga Szelke Timea Imre 《Transition Metal Chemistry》2006,31(3):306-309
Reaction of a series of P-amino and P-cycloalkoxy dibenzo[c.e][1,2]oxaphosphorines (1), (3) and (5) with cis-bis(benzonitrile)dichloroplatinum(II) afforded the title bis(dibenzooxaphosphorino) complexes (2), (4) and (6), respectively. In the case of chiral P-substituents, the complexes (4) and (6) were obtained in homo and heterochiral forms. Stereospecific 1J(195Pt–P) couplings found in the 31P-n.m.r. spectra of the products (2), (4) and (6) suggested the cis orientation of the identical substituents. 相似文献
12.
Attila Makó Zsolt Rapi György Keglevich Áron Szöllősy László Drahos László Hegedűs Péter Bakó 《Tetrahedron: Asymmetry》2010,21(8):919-925
The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfer catalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetric induction. It was found that the position of the substituents in the aromatic ring of the chalcone had an influence both on the chemical yields and enantiomeric excesses. The lowest enantioselectivities (62–83% ee) were found in the case of ortho-substituted model compounds. The highest ee values (ee of 83–97%) were obtained in the case of para-substituted models. From among the chalcone analogues, the maximum ee (90–92%) was detected for the model compound having α-tert-butyl- and β-aryl groups. Using glucose-based crown ether 1, formation of the (?)-enantiomer was preferred, while applying mannose-based 2 as the catalyst, the (+)-enantiomer was in excess. 相似文献
13.
György Keglevich Alajos Grün Erika Bálint Nóra Zsuzsa Kiss Péter Bagi László Tőke 《Structural chemistry》2017,28(2):431-443
Application of the microwave (MW) technique offers many advantages in organophosphorus syntheses. Reluctant reactions may take place on MW irradiation. In most cases, MWs make the reactions more efficient in respect of rate, selectivity and yield. The benefits are shown via representative examples. MW irradiation may replace a catalyst, or simplify catalytic systems. The synthesis of catalysts incorporating heterocyclic P-ligands is also discussed. Where it was relevant, structural chemical details were also provided. 相似文献
14.
Irina Odinets Tamás Kégl Oleg Artyushin Galina Molchanova Tatyana Mastryukova György Keglevich 《Journal of organometallic chemistry》2005,690(14):3456-3464
Asymmetrical cyclic phosphite and phosphinite ligands of a novel type bearing either trifluoromethyl or pentafluorophenyl group were synthesized using >PCl or >PN< species and racemic fluorinated alcohols. The P-ligands were converted to complexes of RhIII(L)(Cp∗)Cl2 type (where L = phosphite or phosphinite) and, in two instances, their stereostructures were evaluated by X-ray analysis. These complexes along with in situ systems, formed from Rh(CO)2(acac) precursor and the corresponding ligand, were tested in the hydroformylation of styrene. Both systems provided excellent hydroformylation activities at 100 °C. Using the RhI in situ systems, moderate and high regioselectivities towards the branched aldehyde (2-phenyl-propanal) were obtained at 100 and 40 °C, respectively. 相似文献
15.
It is known that phosphinic acids do not undergo direct esterification under conventional conditions. However, the reaction may take place on microwave irradiation. 1‐Hydroxy‐3‐phospholene 1‐oxides, 1‐hydroxy‐phospholane 1‐oxides, and a 1‐hydroxy‐1,2,3,4,5,6‐hexahydrophosphinine 1‐oxide were esterified with n‐pentanol, i‐pentanol, n‐octanol, and i‐octanol(2‐ethylhexanol). The phosphinates prepared in 50%–94% yield are all new compounds, and a number of them are useful intermediates. 相似文献
16.
The ring enlargement of 1‐benzyl‐2,5‐dihydro‐1H‐phosphole oxide ( 1 ) via the corresponding 2‐phosphabicyclo[3.1.0]hexane 2‐oxide ( 2 ) afforded, depending on the conditions, the double bond isomers ( A and B ) of 1,2‐dihydrophosphinine oxide 4 or that of 3‐substituted 1,2,3,6‐tetrahydrophosphinine oxides 5 and 6 . Dihydrophosphinine oxides ( 4 ) were suitable starting materials for 1,2,3,4,5,6‐hexahydrophosphinine oxide 7 and 1,2,3,6‐tetrahydrophosphinine oxide 8 obtained by reductive approaches and for the double bond isomers ( A and B ) of 2‐phosphabicyclo[2.2.2]octadiene 2‐oxide 9 and phosphabicyclooctene oxide 10 prepared in Diels–Alder cycloaddition. Precursor 9 was utilized in the fragmentation‐related phosphorylation of alcohols. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:28–34, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20363 相似文献
17.
Ádám Pálvölgyi Zsolt Rapi Olivér Ozohanics Gábor Tóth György Keglevich Péter Bakó 《Research on Chemical Intermediates》2018,44(3):1627-1645
Chiral monoaza-15-crown-5-type lariat ethers annelated to alkyl 4,6-O-benzylidene-α- and β-d-glucopyranosides have been synthesized. These macrocycles generated significant asymmetric induction as phase-transfer catalysts in a few two-phase reactions. The catalytic effect of the lariat ethers with methoxy, ethoxy, and i-propoxy substituents on C-1 of the sugar unit in both α and β positions was compared. In liquid–liquid two-phase reactions, the nature and position of the substituents did not have much effect. The α-anomers were somewhat more efficient in terms of enantioselectivity than the β forms. In asymmetric Darzens condensations, in the epoxidation of trans-chalcone, in the Michael addition of β-nitrostyrene and diethyl acetamidomalonate, and in the reaction of 2-benzylidene-1,3-indandione with diethyl bromomalonate, maximum enantioselectivities of 73, 94, 78, and 72%, respectively, were obtained in presence of glucopyranoside-based lariat ethers as catalysts. 相似文献
18.
Gyrgy Keglevich Helga Szelke gnes Blint Tímea Imre Krisztina Ludnyi Zoltn Nagy Mikls Hanusz Klmn Simon Veronika Harmat Lszl Tke 《Heteroatom Chemistry》2003,14(5):443-451
A series of new P‐methylphenyl P‐heterocycles are introduced. The para and ortho substituted 2,5‐dihydro‐1H‐phosphole oxides ( 1a and 1b ) were converted to the double‐bond isomers ( A and B ) of 1,2‐dihydrophosphinine oxides ( 3a and 3b ) via the corresponding phosphabicyclo[3.1.0]hexane oxides ( 2a or 2b ). Isomeric mixture ( A and B ) of the dihydrophosphinine oxides ( 3a and 3b ) gave, in turn, the isomers ( A and B ) of phosphabicyclo[2.2.2]oct‐5‐enes ( 4a and 4b ) or a phosphabicyclo[2.2.2]octa‐5,7‐diene ( 5 ) in Diels‐Alder reaction with dienophiles. The bridged P‐heterocycles ( 4 and 5 ) were useful in the photo‐ or thermoinduced fragmentation‐related phosphinylation of hydroxy compounds and amines. The new precursors ( 4a and 4b ) were applied in mechanistic investigations. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:443–451, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10176 相似文献
19.
Recent results on the selective reduction of cyclic vinylphosphine oxides and vinylphosphinates, as well as their refunctionalization by the use of borane, are summarized. The selective reduction of the phosphorus moiety of unsaturated phosphonates, phosphinates, and phosphine oxides is also discussed. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:161–167, 2001 相似文献
20.
Gyrgy Keglevich Tungalag Chuluunbaatar Beta Dajka Bat‐Amgalan Namkhainyambuu Krisztina Ludnyi Lszl Tke 《Heteroatom Chemistry》2001,12(7):633-635
Four different [4 + 2] cycloadditions were observed to take place in the equimolar mixtures of two different arylphosphole oxides 2a + 2b or 2b + 2c . In addition to the phosphole oxide dimers 3a‐a and 3b‐b , or 3b‐b and 3c‐c , the crossed cycloadducts 3a‐b and 3b‐a , or 3b‐c and 3c‐b were also formed in considerable portions. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:633–635, 2001 相似文献