Chemo

Distribution by Scientific Domains
Distribution within Chemistry


Selected Abstracts


1-Alkoxyamino-2-nitroalkanes as Key Building Blocks for a Chemo- and Diastereoselective Synthesis of a New Type of Polyfunctionalized N -Alkoxypiperidine

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2010
M. Ángeles López-García
Abstract A highly efficient conversion of ,-nitrostyrenes into a new kind of functionalized N -alkoxy-2-hydroxypiperidine in two steps was developed, giving excellent yields and diastereoselectivity. The prepared compounds are the first examples of N -alkoxy-2-hydroxypiperidines. The synthetic approach involved the conjugate addition of alkoxyamines to ,-nitrostyrenes, followed by Michael addition of the isolated nitroalkoxyamines to ,,,-unsaturated carbonyl compounds, and intramolecular addition of the alkoxyamino group to the carbonyl functionality of the (non-isolated) adducts. Although three stereogenic centers are formed, only one diastereoisomer was detected. This unprecedented sequence of reactions can also be performed in a one-pot fashion. [source]


Convenient Synthesis of Tetrahydro-,-carbolines and Tetrahydroquinolines through a Chemo- and Regioselectivity Switch by a Brønsted Acid Catalyzed, One-Pot, Multicomponent Reaction

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2010
Hong-Gang Cheng
Abstract An efficient, one-pot, multicomponent reaction of aldehydes 1, p -methoxyaniline (2a), and 2-vinylindoles 3 was developed. This approach provides a practical approach to synthetically and biologically significant tetrahydro-,-carboline and tetrahydroquinoline derivatives in good yields through a chemo- and regioselectivity switch, which can be tuned by simply changing the substituent on the indole component under identical reaction conditions. [source]


Chemo-, Regio- and Stereospecific Synthesis of Unnatural, Fluorescent Amino Acids by Condensation of L -Lysine and 1-Vinylpyrrole-2-carbaldehydes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2010
Andrey V. Ivanov
Abstract A new family of unnatural, optically active amino acids containing the pyrrole moiety have been synthesized by condensation of 1-vinylpyrrole-2-carbaldehydes with L -lysine under mild conditions (EtOH, room temp., 2.5,3 h, 0.5 wt.-% of CF3CO2H) in up to 90,% yields. Unlike non-vinylated analogues, 1-vinylpyrrole-2-carbaldehydes react chemo-, regio- and stereospecifically with an ,-amino group only to afford products of exclusively (E) configuration. The amino acids synthesized containing aromatic or condensed aromatic substitutents in the pyrrole ring fluoresce in the UV/Vis region (,max = 350,382 nm, Stokes shifts 6150,7800 cm,1). [source]


The RuO4 -Catalyzed Ketohydroxylation, Part II:A Regio-, Chemo- and Stereoselectivity Study

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2005
Bernd Plietker
Abstract The direct RuO4 -catalyzed ketohydroxylation of olefins is a new and convenient method for the preparation of a wide range of symmetrical and unsymmetrical ,-hydroxy ketones. Since reactions in which two different functional groups are introduced in one step always involve regio-, chemo- and stereoselectivity issues, this paper gives a full account of investigations of various selectivity aspects in the ketohydroxylation. Stereoselectivity issues were examined in the final part of the present report. The Kishi rules, known from OsO4 -catalyzed dihydroxylations, are found to be valid for the RuO4 -catalyzed ketohydroxylation and lead to moderate to good diastereomeric ratios in the oxidation of olefins possessing an allylic center of chirality. Furthermore, competition experiments between different substituted olefins led to a reactivity profile applicable to the prediction of which is the most reactive of different C=C double bonds present in a molecule. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]


Chemo- and Enzyme-Catalyzed Reactions Revealing a Common Temperature-Dependent Dynamic Solvent Effect on Enantioselectivity

HELVETICA CHIMICA ACTA, Issue 11 2003
Gianfranco Cainelli
The enantiomeric ratio E of enzyme-catalyzed (Candida antarctica lipase and lipase PS) and chemo-catalyzed (L -proline-based diamines) acylation reactions of 1-(naphthalen-2-yl)ethanol, 2-phenylpropanol, and 2-benzylpropane-1,3-diol is dependent on solvent and temperature. Plots of ln,E vs. 1/T showed the presence of inversion temperatures (Tinv). The Tinv values for the bio-catalyzed and the chemo-catalyzed reactions are fairly in agreement, and correspond as well to the TNMR values obtained by variable-temperature 13C-NMR experiments on the substrates in the same solvent of the resolution. This result demonstrates that clustering effects in the substrate solvation manage the chemical and the enzymatic enantioselectivity, and, moreover, that the solutesolvent cluster is always the real reacting species in solution for chemical as well as for enzymatic reactions. [source]


Highly Chemo- and Regioselective Reduction of Aromatic Nitro Compounds Catalyzed by Recyclable Copper(II) as well as Cobalt(II) Phthalocyanines

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
Upendra Sharma
Abstract Copper/cobalt phthalocyanines were established for the first time as catalysts for the very efficient chemo- and regioselective reduction of aromatic nitro compounds to generate the corresponding amines. The selective reduction of nitro compounds was observed in the presence of a large range of functional groups such as aldehyde, keto, acid, amide, ester, halogen, lactone, nitrile and heterocyclic functional groups. Furthermore, the present method was found to be highly regioselective towards the reduction of aromatic dinitro compounds in a short time with high yields. In most of the cases the conversion and selectivity were >99% as monitored by GC-MS. The reduction mechanism was elucidated by UV-vis and electrospray ionization quadrupole time-of-flight tandem mass spectrometry. [source]


Chemo- and Stereodivergent Preparation of Terminal Epoxides and Bromohydrins through One-Pot Biocatalysed Reactions: Access to Enantiopure Five- and Six-Membered N-Heterocycles

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010
Fabricio
Abstract Different enantiopure terminal epoxides or bromohydrins have chemoselectively been synthesised in one-pot starting from the corresponding ,-bromo ketones through alcohol dehydrogenase (ADH)-catalysed processes adding an organic co-solvent and tuning appropriately the medium pH and the temperature. Thus, at neutral pH enantiopure bromohydrins were obtained while using basic conditions (pH,9.5,10) epoxides were isolated as the main product. Furthermore, by simple selection of the biocatalyst, chemo- and stereodivergent transformations were achieved to obtain, e.g., enantiopure prolinol or piperidin-3-ol. [source]


Gold- and Silver-Catalyzed Intramolecular Hydroamination of Terminal Alkynes: Water-Triggered Chemo- and Regioselective Synthesis of Fused Tricyclic Xanthines

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009
Deju Ye
Abstract A simple, convenient and green synthetic approach to diverse fused tricyclic xanthines has been developed via gold(I) complex-catalyzed intramolecular hydroamination or silver(I)-catalyzed isomerization-hydroamination of terminal alkynes under microwave irradiation in water. The first synthesis of N9-annelated xanthines has also been reported. [source]


Unprecedent Chemo- and Stereoselective Palladium-Catalysed Methoxycarbonylation of Norbornene

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009
Carolina Blanco
Abstract Catalytic systems able to control chemo- and stereoselectivity have been tested in the palladium-catalysed methoxycarbonylation of norbornene. An enantioselectivity of up to 40% was obtained. [source]


Acid-Catalyzed Intramolecular [2+2] Cycloaddition of Ene-allenones: Facile Access to Bicyclo[n.2.0] Frameworks,

ANGEWANDTE CHEMIE, Issue 39 2009
Jun-Feng Zhao
Zwei plus zwei macht zwei Ringe: Eine hoch effiziente säurekatalysierte intramolekulare [2+2]-Cycloaddition von Enallenonen (siehe Schema; Tf: Trifluormethansulfonyl) ergibt unter milden Bedingungen gespannte Bicyclo[n.2.0]-Gerüste mit benachbarten quartären und tertiären Stereozentren in ausgezeichneten Ausbeuten und Chemo-, Regio- und Diastereoselektivitäten. [source]


Die Anwendung von Viren in Chemo- und Biosensoren

ANGEWANDTE CHEMIE, Issue 37 2009
Chuanbin Mao Prof.
Abstract Viren haben sich in jüngster Zeit als einzigartige Hilfsmittel für den empfindlichen und selektiven Nachweis von Analyten wie Explosivstoffen, Proteinen, Bakterien, Viren, Sporen und Toxinen erwiesen. Auf Bakterien spezialisierte Viren, die Bakteriophagen , oder kurz Phagen ,, wurden dabei am intensivsten untersucht: Zielspezifische nichtlysierende Phagen (sowie von diesen präsentierte Peptide und Proteine) können mithilfe hoch entwickelter Phagendisplaytechniken identifiziert werden, und lysierende Phagen können gezielt Bakterien aufbrechen und spezifische Zellmarker wie Enzyme ausschütten, die analysiert werden können. Darüber hinaus sind Phagen chemisch wie thermisch hinreichend stabil, und sie lassen sich mit Molekülen kuppeln und mit Nanomaterialien kombinieren und auf der Oberfläche eines Signalwandlers in einem Analysesystems verankern. Im Mittelpunkt dieses Aufsatzes stehen Fortschritte bei der Verwendung von Phagen in Chemo- und Biosensoren durch Kombination mit etablierten analytischen Techniken. Überdies werden aktuelle Entwicklungen bei der Verwendung von Virus-Nanomaterial-Kompositen und anderen Viren in Sensoranwendungen vorgestellt. [source]


Nickel-Catalyzed Three-Component [2+2+2] Cycloaddition Reaction of Arynes, Alkenes, and Alkynes,

ANGEWANDTE CHEMIE, Issue 31 2009
Zaozao Qiu
Drei in einem: Nickelkatalysierte Dreikomponenten-Cycloadditionen von leicht zugänglichen Arinen, aktivierten Alkenen und Alkinen ermöglichen den Zugang zu einer Serie von substituierten 1,2-Dihydronaphthalinen in mittleren bis sehr guten Ausbeuten und mit ausgezeichneten Chemo- und Regioselektivitäten (siehe Schema; TMS=Trimethylsilyl, cod=1,5-Cyclooctadien). [source]


ChemInform Abstract: Rhodium-Catalyzed Chemo- and Stereoselective Arylative and Alkenylative Cyclization Reactions of Unsymmetric Diynes Containing a Terminal Alkyne Moiety with Organoboronic Acids.

CHEMINFORM, Issue 38 2010
Levent Artok
Abstract A variety of 1,6-diynes containing a terminal alkyne, e.g. (I) or (IV), reacts with aryl- (II) or alkenylboronic acids (VI) with excellent chemo- and stereoselectivity in the presence of a Rh2(cod)2(O-Me)2 complex to give the 5-exo cyclization products, exclusively. [source]


ChemInform Abstract: Highly Efficient Chemo- and Regioselective Silylation of -OH Groups and Cyanosilylation of Aldehydes Promoted by TiCl2(OTf),SiO2 as a New Recyclable Catalyst.

CHEMINFORM, Issue 10 2010
Habib Firouzabadi
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: One-Pot Synthesis of 2-Pyridones via Chemo- and Regioselective Tandem Blaise Reaction of Nitriles with Propiolates.

CHEMINFORM, Issue 7 2010
Yu Sung Chun
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: Generation of Hafnium Hydride and Its Application to Chemo- and Diastereoselective Reactions.

CHEMINFORM, Issue 43 2009
Ikuya Shibata
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: Chemo-/Regioselective Synthesis of 6-Unsubstituted Dihydropyrimidinones, 1,3-Thiazines and Chromones via Novel Variants of Biginelli Reaction.

CHEMINFORM, Issue 37 2009
Jie-Ping Wan
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: A Multicomponent Reaction of Arynes, Isocyanides, and Terminal Alkynes: Highly Chemo- and Regioselective Synthesis of Polysubstituted Pyridines and Isoquinolines.

CHEMINFORM, Issue 35 2009
Feng Sha
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: Highly Chemo- and Enantioselective Hydrogenation of Linear ,,,-Unsaturated Ketones.

CHEMINFORM, Issue 1 2009
Sheng-Mei Lu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: Highly Chemo- and Diastereoselective Synthesis of Substituted Tetrahydropyran-4-ones via Organocatalytic oxa-Diels,Alder Reactions of Acyclic ,,,-Unsaturated Ketones with Aldehydes.

CHEMINFORM, Issue 25 2008
Liang-Qiu Lu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: Chemo- and Enantioselective Sulfoxidation of Bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) into Chiral BEDT-TTF-Sulfoxide.

CHEMINFORM, Issue 19 2008
Marcos Chas
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


Chemo- and Stereoselectivity of the Reaction of Aromatic Aldehydes with Triphenylphosphine and Trichloroacetic Acid Derivatives.

CHEMINFORM, Issue 40 2006
E. D. Matveeva
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


Highly Regio-, Chemo- and Diastereoselective Synthesis of Oxa-Bridged Spirocycles: A Novel Observation of Reverse Selectivity.

CHEMINFORM, Issue 50 2005
Sengodagounder Muthusamy
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


Chemo- and Stereoselectivity in Titanium-Mediated Regioselective Ring-Opening Reaction of Epoxides at the More Substituted Carbon.

CHEMINFORM, Issue 44 2005
Tetsuaki Tanaka
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


Totally Chemo- and Regioselective Cobalt(I)-Mediated Formal Intermolecular Cyclotrimerization of Alkynes.

CHEMINFORM, Issue 37 2004
Gaelle Chouraqui
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


Chemo- and Stereoselective Palladium-Catalyzed Allylic Alkylations Controlled by Silicon.

CHEMINFORM, Issue 48 2003
Claude Commandeur
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


One-Pot Palladium-Catalyzed Highly Chemo-, Regio-, and Stereoselective Synthesis of trans-Stilbene Derivatives.

CHEMINFORM, Issue 13 2003
A Concise, Convenient Synthesis of Resveratrol (XII).
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


ChemInform Abstract: Innovative Synthesis of 4-Carbaldehydepyrrolin-2-ones by Zwitterionic Rhodium Catalyzed Chemo- and Regioselective Tandem Cyclohydrocarbonylation/CO Insertion of ,-Imino Alkynes.

CHEMINFORM, Issue 6 2002
Bernard G. Van den Hoven
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: An Efficient Chemo- and Regioselective Oxidative Nuclear Bromination of Activated Aromatic Compounds Using Lithium Bromide and Ceric Ammonium Nitrate.

CHEMINFORM, Issue 52 2001
Subhas Chandra Roy
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


ChemInform Abstract: Chemo-, Regio- and Stereoselective Conversion of P-Chirogenic Phosphorus Borane Complexes into Their P=O or P=S Derivatives.

CHEMINFORM, Issue 50 2001
Jacques Uziel
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]