EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007
Sumon Nag
Abstract Reaction of five N -(4- R -phenyl)picolinamides (R = OCH3, CH3, H, Cl, and NO2) with [Ru(PPh3)2(CO)2Cl2] in refluxing 2-methoxyethanol in the presence of a base (NEt3) affords two geometrical isomers of a group of complexes (1-R and 2-R), each of which contains an amide ligand coordinated to the metal center as a monoanionic bidentate N,N donor along with two triphenylphosphanes, a carbonyl, and a hydride. Similar reaction of N -(naphthyl)picolinamide with [Ru(PPh3)2(CO)2Cl2] affords an organometallic complex, 3, in which the amide ligand is coordinated to the metal center, by C,H activation of the naphthyl ring at the 8-position, as a dianionic tridentate N,N,C donor along with two triphenylphosphanes and one carbonyl. Structures of the 1-OCH3, 2-CH3, and 3 complexes have been determined by X-ray crystallography. In all the complexes the two triphenylphosphanes are trans. In the 1-R complexes the hydride is trans to the pyridine nitrogen and in the 2-R complexes it is trans to the amide-nitrogen. All the complexes are diamagnetic, and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a RuII,RuIII oxidation within 0.71,0.93 V versus SCE. An oxidation and a reduction of the coordinated amide ligand are also observed within 1.29,1.69 V versus SCE and ,1.02 to ,1.21 V versus SCE respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Contribution to the Reactivity of N,N, -Diaryl-1,4-diazabutadienes Aryl,N=CH,CH=N,Aryl (Aryl = 2,6-Dimethylphenyl; 2,4,6-Trimethylphenyl) Towards Boron Trichloride

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2006
Lothar Weber
Abstract The reaction of Aryl,N=CH,CH=N,Aryl (3a: Aryl = 2,6-Me2C6H3; 3b: Aryl = 2,4,6-Me3C6H2) with 2 equiv. BCl3 in a toluene/hexane mixture at ,50 °C led to an inseparable mixture of borolium salts [Aryl,Na=CH,CH=N(Aryl)BCl2(Na,B)]+BCl4, (4a: Aryl = 2,6-Me2C6H3; 9a: Aryl = 2,4,6-Me3C6H2) and [Aryl,Na=CH,C(Cl)=N(Aryl)BCl2(Na,B)]+BCl4, (4b: Aryl = 2,6-Me2C6H3; 9b: Aryl = 2,4,6-Me3C6H2) and the bicyclic species [HCa=N(Aryl)BCl2N(Aryl),Cb=(Ca,Cb)]2 (5: Aryl = 2,6-Me2C6H3; 10: Aryl = 2,4,6-Me3C6H2). Sodium amalgam reduction of borolium salts 4a,b and 9a,b afforded inseparable mixtures of the diazaboroles 2,6-Me2C6H3NaCH=CR,Nb(2,6-Me2C6H3)BCl(Na,B) (1: R = H; 6: R = Cl) and 2,4,6-Me3C6H2NaCH=CR,Nb(2,4,6-Me3C6H2)BCl(Na,B) (2: R = H; 11: R = Cl). In order to obtain pure 1 and 2, diazabutadienes 3a and 3b were slowly combined with 2 equiv. BCl3 in the same solvents at ,78 °C. The acyclic adducts Cl3BN(Aryl)=CH,CH=N(Aryl)BCl3 (7a: Aryl = 2,6-Me2C6H3; 7b: Aryl = 2,4,6-Me3C6H2) were reduced with sodium amalgam to furnish the aminoboranes Cl2BN(Aryl)CH=CH,N(Aryl)BCl2 (8: Aryl = 2,6-Me2C6H3; 12: Aryl = 2,4,6-Me3C6H2). Stirring solutions of 8 and 12 in the presence of CaH2 cleanly gave the diazaboroles 1 and 2, respectively. The novel compounds were characterized by elemental analyses and 1H-, 11B-, 13C NMR and mass spectra. The molecular structures of 1, 4a, 5 and 8 were elucidated by single X-ray diffraction analyses. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

The Use of a Bifunctional Copper Catalyst in the Cross-Coupling Reactions of Aryl and Heteroaryl Halides with Terminal Alkynes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2008
Minyan Wu
Abstract Copper-catalyzed cross-coupling reactions of aryl halides and heteroaryl halides with terminal alkynes were carried out in DMF at 110,130 °C to provide the corresponding coupling products in satisfactory-to-good yields by using inexpensive 8-hydoxyquinoline as the ligand. Noteworthy is that the bifunctional copper catalyst was successfully applied in this alkynylation reaction for the first time.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

An Efficient N -Arylation of Heterocycles with Aryl-, Heteroaryl-, and Vinylboronic Acids Catalyzed by Copper Fluorapatite

HELVETICA CHIMICA ACTA, Issue 5 2010
Lakshmi Kantam, Mannepalli
Abstract N -Arylation of N-containing heterocycles, such as pyrazoles, imidazoles, and benzimidazoles with aryl-, heteroaryl-, and vinylboronic acids was efficiently carried out by copper fluorapatite (CuFAP) catalyst in MeOH at room temperature under base-free conditions. The N- arylated heterocycles were isolated in good-to-excellent yields. [source]

Are Oxazolidinones Really Unproductive, Parasitic Species in Proline Catalysis?

HELVETICA CHIMICA ACTA, Issue 3 2007
Experiments Pointing to an Alternative View, Thoughts
Abstract The N,O-acetal and N,O-ketal derivatives (oxazolidinones) formed from proline, and aldehydes or ketones are well-known today, and they are detectable in reaction mixtures involving proline catalysis, where they have been considered ,parasitic dead ends'. We disclose results of experiments performed in the early 1970's, and we describe more recent findings about the isolation, characterization, and reactions of the oxazolidinone derived from proline and cyclohexanone. This oxazolidinone reacts (THF, room temperature) with the electrophiles , -nitrostyrene and chloral (=trichloroacetaldehyde), to give the Michael and aldol adduct, respectively, after aqueous workup (Scheme,5). The reactions occur even at ,75° when catalyzed with bases such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or EtN(i-Pr)2 (DIPEA) (10%; Table,1). It is shown by NMR (Figs.,1 and 3) and IR analysis (Figs.,2 and 4) that the primarily detectable product (before hydrolysis) of the reaction with the nitro-olefin is again an oxazolidinone. When dissolved in hydroxylic solvents such as MeOH, ,hexafluoroisopropanol' ((CF3)2CHOH; HFIP), AcOH, CF3COOH, or in LiBr-saturated THF, the ring of the oxazolidinone from cyclohexanone and proline opens up to the corresponding iminium ion (Tables,2,4), and when treated with strong bases such as DBU (in (D8)THF) the enamino-carboxylate derived from proline and cyclohexanone is formed (Scheme,8). Thus, the two hitherto putative participants (iminium ion and enamine) of the catalytic cycle (Scheme,9) have been characterized for the first time. The commonly accepted mechanism of the stereoselective C,C- or C,X-bond-forming step (i.e., A,D) of this cycle is discussed and challenged by thoughts about an alternative model with a pivotal role of oxazolidinones in the regio- and diastereoselective formation of the intermediate enamino acid (by elimination) and in the subsequent reaction with an electrophile (by trans -addition with lactonization; Schemes,11,14). The stereochemical bias between endo - and exo -space of the bicyclo[3.3.0]octane-type oxazolidinone structure (Figs.,5 and 6) is considered to possibly be decisive for the stereochemical course of events. Finally, the remarkable consistency, with which the diastereotopic Re -face of the double bond of pyrrolidino-enamines (derived from proline) is attacked by electrophiles (Schemes,1 and 15), and the likewise consistent reversal to the Si -face with bulky (Aryl)2C-substituents on the pyrrolidine ring (Scheme,16) are discussed by invoking stereoelectronic assistance from the lone pair of pyramidalized enamine N-atoms. [source]

New Synthesis of Aryl and Heteroaryl N- Acylureas via Microwave-Assisted Palladium-Catalysed Carbonylation

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
David Liptrot
Abstract A new, practical synthesis of aryl and heteroaryl N- acylureas has been developed via palladium-catalysed carbonylation of aryl or heteroaryl halides in the presence of urea nucleophiles. A range of reactions illustrating the wide scope of this reaction was carried out under microwave irradiation, using either carbon monoxide gas in a vessel equipped with a gas inlet adapter, or molybdenum hexacarbonyl as the carbon monoxide source in standard microwave vials. The reactions proceeded in good to excellent yields. To illustrate the usefulness of this method a one-step synthesis of the important insecticide diflubenzuron is reported. [source]

Cyclopalladated Ferrocenylimine as Efficient Catalyst for the Syntheses of Arylboronate Esters

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
Lianhui Wang
Abstract The cyclopalladated ferrocenylimine I and its phosphine adducts IIa,f were prepared and evaluated in the borylation of aryl halides. The tricyclohexylphosphine adduct IIb exhibited highly catalytic activity for the coupling of aryl and heteroaryl bromides containing various functional groups with low catalyst loading (2,mol%). Aryl and heteroaryl chlorides were smoothly converted into the corresponding boronates in the presence of the monophosphinobiaryl ligand (XPhos) adduct IIf. It was proposed that palladacycle was only a reservoir of the catalytically active species from the investigation on the reaction mechanism. [source]

Synthesis of Sulfoximines and Sulfilimines with Aryl and Pyrazolylmethyl Substituents

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Olga García Mancheño
Abstract Sulfoximines bearing pyrazolylmethyl and aryl substituents, which are relevant to the crop protection industry, and their corresponding sulfilimine intermediates, have been prepared from sulfide precursors by either iron-catalyzed nitrogen transfer reactions or metal-free imination procedures. Whereas the former approach leads to N -nosyl-substituted products, the latter affords N -cyano derivatives. [source]

Palladium-Catalyzed Decarboxylative sp - sp2 Cross-Coupling Reactions of Aryl and Vinyl Halides and Triflates with ,,,-Ynoic Acids using Silver Oxide

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009
Hyunseok Kim
Abstract Palladium-catalyzed decarboxylative sp-sp2 cross-coupling reactions of aryl and vinyl halides and triflates with ,,,-ynoic acids using silver oxide have been developed. A variety of ,,,-ynoic acids were readily decarboxylated in the presence of silver oxide and then, generated in situ, silver acetylides were coupled with electrophiles in the presence of a palladium(0) catalyst under neutral conditions, producing either symmetrical or unsymmetrical diarylacetylenes, arylalkylacetylenes and arylvinylacetylenes in good to excellent yields. [source]

Expanded Heterogeneous Suzuki,Miyaura Coupling Reactions of Aryl and Heteroaryl Chlorides under Mild Conditions

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009
Dong-Hwan Lee
Abstract A mesoporous LTA zeolite (MP-LTA)-supported palladium catalyst was developed for the highly efficient Suzuki,Miyaura reaction of aryl and heteroaryl chlorides. The couplings of various aryl chlorides with arylboronic acids in aqueous ethanol were efficiently achieved in the presence of 1.0,mol% of the catalyst. Furthermore, the scope of this catalyst was extended to the coupling of heteroaryl chlorides. Regardless of the substituents, all of the coupling reactions were very clean and highly efficient under mild heating. It shows that our catalyst is one of the most powerful heterogeneous catalysts for the coupling of a wide range of aryl and heteroaryl chlorides. The catalyst could be repetitively used at least 10 times without a significant loss of its catalytic activity. Compared to mesoporous SBA-15 and MCM-41 materials, the MP-LTA support proved to be very stable and robust to prevent degradation upon reuse. [source]

Homobenzotetramisole-Catalyzed Kinetic Resolution of ,-Aryl-, ,-Aryloxy-, and ,-Arylthioalkanoic Acids

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
Xing Yang
Abstract Effective kinetic resolutions of ,-aryl-, ,-aryloxy-, and ,-arylthioalkanoic acids have been achieved via in situ generation of their symmetrical anhydrides and enantioselective alcoholysis in the presence of homobenzotetramisole (HBTM) 3. [source]

Iodobenzene diacetate on alumina: Efficient synthesis of 1,3,4-oxadiazolyl-1,8-naphthyridines in solventless system using microwaves

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2006
K. Mogilaiah
1-(5-Aryl-[1,3,4]oxadiazol-2-ylmethyl)-3-(p -methoxyphenyl)-1H -[1,8]naphthyridin-2-ones (5) were synthesized by the oxidative cyclization of [2-oxo-3-(p -methoxyphenyl)-2H -[1,8]naphthyridin-1-yl]acetic acid arylidene-hydrazides (4) with alumina-supported iodobenzene diacetate (IBD) in solvent-free conditions under microwave irradiation. The products are obtained in good yields and in a state of high purity. [source]

Enantiodifferentiating endo -Selective Oxylactonization of ortho -Alk-1-enylbenzoate with a Lactate-Derived Aryl-,3 -Iodane,

ANGEWANDTE CHEMIE, Issue 39 2010
Prof.
Erfolg mit Lactat: Die asymmetrische Synthese von 3-Alkyl-4-oxyisochroman-1-on gelingt durch die Titelreaktion mit einer Serie optisch aktiver hypervalenter Iod(III)-Reagentien, die aus Lactat oder Valin als chiraler Quelle präpariert wurden. Die Oxylactonisierung ist hoch regio-, diastereo- und enantioselektiv. [source]

Palladium-Catalyzed ,-Arylation of ,,,-Unsaturated Esters from Silyl Ketene Acetals,

ANGEWANDTE CHEMIE, Issue 33 2010
David
Smarter Katalysator: Eine Methode für die Palladium-katalysierte ,-Arylierung von ,,,-ungesättigten Estern wurde entwickelt, die über Silylketenacetale verläuft und ohne Fluorid-Aktivatoren auskommt. Die Kupplung gelingt mit elektronenreichen und elektronenarmen Aryl- und Vinylbromiden in hohen Ausbeuten, und andere funktionelle Gruppen werden gut toleriert. [source]

Palladium-Catalyzed Coupling Reactions: Carbonylative Heck Reactions To Give Chalcones,

ANGEWANDTE CHEMIE, Issue 31 2010
Xiao-Feng Wu
Chalkone leicht gemacht: Carbonylierende Heck-Reaktionen von Aryl- oder Alkenyltriflaten mit Kohlenmonoxid und aromatischen Olefinen gelingen in Gegenwart von Palladiumkatalysatoren (siehe Schema; dppp=1,3-Bis(diphenylphosphino)propan, Tf=Triflat; R=Aryl, Vinyl). Dieses Verfahren schließt eine Lücke zwischen carbonylierenden Suzuki- und Sonogashira-Reaktionen. [source]

Carben-Übergangsmetallkomplexe durch zweifache C-H-Bindungsaktivierung

ANGEWANDTE CHEMIE, Issue 28 2010
Helmut Werner Prof.
Abstract Die Aktivierung einer einzelnen sp3 -C-H-Bindung von Alkanen und ihren Derivativen durch elektronenreiche Übergangsmetallkomplexe wurde seit den 1982 erschienenen bahnbrechenden Arbeiten von Bergman und Graham zu einem viel bearbeiteten Forschungsprojekt. Zehn Jahre später wurde gezeigt, dass Verbindungen der 5d-Elemente, z.,B. von Osmium und Iridium, auch zu einer zweifachen ,-C-H-Bindungsaktivierung von Alkan- oder Cycloalkanderivaten fähig sind, sofern diese eine funktionelle Gruppe wie OR oder NR2 besitzen. Damit war ein neuer Zugang zu Carbenkomplexen der Übergangsmetalle vom Fischer-Typ eröffnet. Nachfolgende Arbeiten konzentrierten sich zuerst auf die Umwandlung von Alkyl(methyl)- und Aryl(methyl)ethern in Oxocarben- und von Dimethylaminen in Aminocarbenliganden. Kürzlich wurde gezeigt, dass so hergestellte quadratisch-planare Oxocarbeniridium(I)-Komplexe zu einem ungewöhnlichen Reaktivitätstyp befähigt sind. Sie reagieren mit CO2,, CS2,, COS, PhNCO und PhNCS gemäß einer Atom- oder Gruppentransfermetathese, für die es bisher kein Beispiel gibt. Organoazide RN3 und N2O verhalten sich ähnlich. Jüngste Ergebnisse weisen darauf hin, dass solche Metathesereaktionen auch katalytisch durchgeführt werden können, wodurch sich eine neue Möglichkeit zur Funktionalisierung von C-H-Bindungen bietet. [source]

Palladium-Catalyzed Arylative Ring-Opening Reactions of Norbornenols: Entry to Highly Substituted Cyclohexenes, Quinolines, and Tetrahydroquinolines,

ANGEWANDTE CHEMIE, Issue 26 2010
Michael Waibel Dr.
Retro-Design: Palladium-katalysierte Retro-Allylierungen ausgehend von tertiären Norbornenolen ermöglichen deren Kupplung mit Aryl- oder Vinylhalogeniden unter Bildung tetrasubstituierter Cyclohexene mit hervorragender Regio- und Diastereoselektivität (siehe Schema). Dominovarianten dieser Reaktion eröffnen den Zugang zu hoch funktionalisierten Chinolinen und Tetrahydrochinolinen. [source]

Convenient Electrophilic Fluorination of Functionalized Aryl and Heteroaryl Magnesium Reagents,

ANGEWANDTE CHEMIE, Issue 12 2010
Shigeyuki Yamada Dr.
Ganz einfach: Die elektrophile Fluorierung einer Vielzahl aromatischer und heteroaromatischer Grignard-Reagentien gelingt glatt mit (PhSO2)2NF als Fluorierungsmittel in einer 4:1-Mischung aus CH2Cl2 und Perfluordecalin (siehe Schema). In diesem Lösungsmittelsystem sind die meisten Nebenreaktionen zurückgedrängt. [source]

Efficient Synthesis of Aryl Fluorides,

ANGEWANDTE CHEMIE, Issue 12 2010
Pazhamalai Anbarasan Dr.
Bildung von C-F-Bindungen: Eine neuartige elektrophile Fluorierung von Aryl- und Heteroaryl-Grignard-Reagentien wurde entdeckt und zur effizienten Synthese verschiedener Arylfluoride eingesetzt (siehe Bild; THF=Tetrahydrofuran). [source]

Iminium,Allenamine Cascade Catalysis: One-Pot Access to Chiral 4H -Chromenes by a Highly Enantioselective Michael,Michael Sequence,

ANGEWANDTE CHEMIE, Issue 8 2010
Xinshuai Zhang
Doppelter Michael: Eine Michael-Michael-Reaktionskaskade von Aryl- oder Alkylalkinalen, die eine neuartige Iminium-Allenamin-Sequenz umfasst, wird effizient durch einen chiralen Diphenylprolinol-TBDMS-Ether katalysiert. Auf diesem Weg sind funktionalisierte 4H -Chromene in hohen Ausbeuten zugänglich. TBDMS=tert -Butyldimethylsilyl. [source]

Highly Selective Oxidation of Organosilanes to Silanols with Hydrogen Peroxide Catalyzed by a Lacunary Polyoxotungstate,

ANGEWANDTE CHEMIE, Issue 47 2009
Ryo Ishimoto
Silanolsynthese: Das lakunare Polyoxowolframat (nBu4N+)4[,-SiW10O34(H2O)2] (I) mit zwei Leerstellen ist ein effizienter Homogenkatalysator für die hoch selektive Oxidation von Organosilanen zu Silanolen mit 30,60,% H2O2. Silane 1 mit Aryl-, Alkyl-, Alkenyl-, Alkinyl- und Alkoxygruppen werden in hohen Ausbeuten chemoselektiv zu den jeweiligen Silanolen 2 umgesetzt, wobei nur ein Äquivalent an wässrigem H2O2 in Bezug auf das Substrat benötigt wird. [source]

Facile Generation of a Strained Cyclic Vinyl Cation by Thermal Solvolysis of Cyclopent-1-enyl-,3 -bromanes,

ANGEWANDTE CHEMIE, Issue 47 2009
Kazunori Miyamoto Prof.
Bromhaltige Abgangsgruppe: Die einfache Solvolyse von Cyclopent-1-enyl-,3 -bromanen bei Raumtemperatur liefert das stark gespannte Cyclopent-1-enyl-Kation (siehe Schema). Diese außergewöhnliche unimolekulare Dissoziation beruht auf der Wirkung der Aryl-,3 -bromanyl-Gruppen als gute Abgangsgruppen. [source]

Effiziente enantioselektive Synthese von optisch aktiven Diolen durch asymmetrische Hydrierung mittels modular aufgebauter chiraler Metallkatalysatoren,

ANGEWANDTE CHEMIE, Issue 41 2009
Renat Kadyrov Dr.
Wertvolle vicinale 1,2-Diole werden mit hohen Enantiomerenüberschüssen in der asymmetrischen Ruthenium-katalysierten Hydrierung von Aryl- und , als besonders anspruchsvollen Substraten , Alkyl-substituierten ,-Hydroxyketonen erhalten (siehe Schema). Die Liganden zeichnen sich durch ihren modularen Aufbau aus und verfügen über hervorragende seitendifferenzierende Eigenschaften. [source]

The Newman,Kwart Rearrangement of O -Aryl Thiocarbamates: Substantial Reduction in Reaction Temperatures through Palladium Catalysis,

ANGEWANDTE CHEMIE, Issue 41 2009
Jeremy
Viel ,cooler": Dank der Entwicklung eines Katalysators für die Newman-Kwart-Umlagerung lassen sich die harschen thermischen Bedingungen der unkatalysierten Reaktion nun vermeiden (siehe Schema). Ersten mechanistischen Studien zufolge (Isotopenmarkierung (2H, 18O, 34S), kinetische Messungen und DFT-Rechnungen) verläuft die Reaktion über eine oxidative Fünf-Zentren-Addition zu einem Pd-S-Komplex mit intermolekularem Austausch von Aryl- und Thiocarbamat-Gruppen durch Dimerisierung des Ruhekomplexes. [source]

Synthesis of Aziridines by Palladium-Catalyzed Reactions of Allylamines with Aryl and Alkenyl Halides: Evidence of a syn -Carboamination Pathway,

ANGEWANDTE CHEMIE, Issue 39 2009
Sayuri Hayashi
Selektiv zum Aziridin: Die palladiumkatalysierten Umsetzungen eines N -Arylallylamins mit einem Aryl- oder Alkenylhalogenid (siehe Schema; dba=Dibenzylidenaceton, SPhos=2-Dicyclohexylphosphanyl-2,,6,-dimethoxybiphenyl) führten durch eine intramolekulare Cyclisierung unter C-C-Bindungsbildung zu den Arylmethyl-substituierten Aziridinen. Experimente zur Aufklärung des Mechanismus werden beschrieben. [source]

Katalytische C-C-, C-N- und C-O-Ullmann-Kupplungen

ANGEWANDTE CHEMIE, Issue 38 2009
Florian Monnier Dr.
Abstract Kupferkatalysierte Ullmann-Kondensationen sind Schlüsselreaktionen in der organischen Synthese zur Bildung von Kohlenstoff- Heteroatom- und Kohlenstoff-Kohlenstoff-Bindungen. Die mit diesen Methoden erhältlichen Strukturmotive sind in biologisch aktiven Molekülen und vielen Materialvorstufen weit verbreitet. Dementsprechend waren intermolekulare Ullmann-Reaktionen zur Kupplung von Aryl- und Vinylhalogeniden mit N-, O- und C-Nucleophilen Gegenstand zahlreicher Studien, und dieser Kurzaufsatz beleuchtet die aktuellsten und wichtigsten Entwicklungen auf diesem Gebiet seit 2004. [source]

pH-Regulated Asymmetric Transfer Hydrogenation of Quinolines in Water,

ANGEWANDTE CHEMIE, Issue 35 2009
Chao Wang
In gepuffertem Wasser wurde ein breites Spektrum von Chinolinen durch asymmetrische Transferhydrierung an der Luft mit dem Rhodiumkatalysator 1 und Natriumformiat als Wasserstoffquelle mit ausgezeichneten Enantioselektivitäten zu den präparativ nützlichen 1,2,3,4-Tetrahydrochinolinen umgesetzt (siehe Schema; R=H, Me, F, Cl, Br, OMe; R,=Alkyl, Aryl). [source]

Eisen-katalysierte Carbonylierungen: selektive und effiziente Synthese von Succinimiden,

ANGEWANDTE CHEMIE, Issue 33 2009
Katrin Marie Driller
Eine einstufige Synthese mit [Fe(CO)5] oder [Fe3(CO)12] als Katalysator führt ausgehend von kommerziell erhältlichen Aminen oder Ammoniak und Alkinen zu unterschiedlich substituierten Succinimiden. Die Umsetzungen sind äußerst selektiv und liefern ein breites Spektrum an Produkten (siehe Schema; R,=H, Alkyl, Aryl; R,,, R,,,=Alkyl, Aryl). [source]

Design and Synthesis of a Focused Library of Novel Aryl- and Heteroaryl-Ketopiperazides

ARCHIV DER PHARMAZIE, Issue 12 2004
Matthias Gerlach
Abstract 1-Phenyl-4-piperazinyl-carbonyl-substituted nitrogen-containing heterocycles were discovered at Zentaris as a new class of potent, synthetic, small molecule tubulin inhibitors with strong antiproliferative activity. The lead structure of this class, D-24203, proved to be a potent inhibitor of in vivo tumor growth in different xenograft models including mammary and renal cancers. As part of our efforts in the lead optimization process to expand structural diversity as well as to optimize bioavailability parameters such as solubility and metabolic stability for these compounds, we produced and evaluated a focused library containing 320 compounds. Five new heterocyclic compound classes with comparable activity properties in the cytotoxicity and tubulin polymerization assay could be identi fied. In silico calculated bioavailability parameters for selected library members provides new compound classes with improved solubility properties. Library design, development of adequate solution phase methodology, and synthesis will be presented, as well as results of lead optimization. [source]

ChemInform Abstract: Rational Exploration of N-Heterocyclic Carbene (NHC) Palladacycle Diversity: A Highly Active and Versatile Precatalyst for Suzuki,Miyaura Coupling Reactions of Deactivated Aryl and Alkyl Substrates.

CHEMINFORM, Issue 39 2010
Guang-Rong Peh
Abstract A small library of NHC-palladacycles is prepared by heating readily available palladacycle acetates with imidazolium salts. [source]