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Diastereo
Kinds of Diastereo Selected AbstractsHighly Diastereo- and Enantioselective Catalytic Domino Thia-Michael/Aldol Reactions: Synthesis of Benzothiopyrans with Three Contiguous StereocentersADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2 2008Gui-Ling Zhao Abstract Highly enantioselective organocatalytic domino thia-Michael/aldol reactions between 2-mercaptoacetophenone and ,,,-unsaturated aldehydes are presented. The reactions proceed with excellent chemo-, diastereo- and enantioselectivity to give the corresponding benzothiopyran derivatives in high yields with up to >15:1 dr and 96 to >99,% ee. [source] Diastereo- and Enantioselective Gold(I)-Catalyzed Intermolecular Tandem Cyclization/[3+3]Cycloadditions of 2-(1-Alkynyl)-2-alken-1-ones with Nitrones,ANGEWANDTE CHEMIE, Issue 37 2010Feng Liu Gold mit verschiedenen Begleitern: Eine asymmetrische formale [3+3]-Cycloaddition von 2-(1-Alkinyl)-2-alken-1-onen mit Nitronen wurde entwickelt. Neben der etablierten Kombination mit 1 erwies sich auch die mit 2 als effektiver und zuverlässiger chiraler Goldkatalysator für diese Reaktion. [source] Catalytic Asymmetric Reductive Amination of ,-Branched Ketones,ANGEWANDTE CHEMIE, Issue 27 2010Vijay Maßgebliche Substituenten: Die Titelreaktion nutzt die dynamische kinetische Racematspaltung und liefert so cis -2-substituierte Cyclohexylamine mit hohen Diastereo- und Enantioselektivitäten. [source] Asymmetric Three-Component Inverse Electron-Demand Aza-Diels,Alder Reaction: Efficient Synthesis of Ring-Fused Tetrahydroquinolines,ANGEWANDTE CHEMIE, Issue 22 2010Mingsheng Xie Drei sind nicht einer zu viel: Die Titelreaktion zwischen Aldehyden, Anilinen und Cyclopentadien liefert in Gegenwart von 0.5,5,Mol-% eines N,N, -Dioxid-Scandium-Komplexes in einem Eintopfprozess in guter Ausbeute und mit ausgezeichneter Diastereo- und Enantioselektivität ringanellierte Tetrahydrochinoline mit drei benachbarten Stereozentren. [source] Diastereo- and Enantioselective Catalytic Tandem Michael Addition/Mannich Reaction: Access to Chiral Isoindolinones and Azetidines with Multiple Stereocenters,ANGEWANDTE CHEMIE, Issue 15 2010Shengmei Guo Michael und Mannich arbeiten zusammen: Ein schneller und verlässlicher Zugang zu hochfunktionalisierten chiralen Isoindolindon- und Azetidinderivaten mit mehreren benachbarten Stereozentren wird vorgestellt (siehe Schema). [source] Phosphoramidite: privilegierte Liganden in der asymmetrischen KatalyseANGEWANDTE CHEMIE, Issue 14 2010Johannes Abstract Die asymmetrische Katalyse mit Übergangsmetallkomplexen ist die Grundlage unzähliger stereoselektiver Umwandlungen und hat damit das Bild der modernen Synthesechemie gewandelt. Der Schlüssel zum Erfolg war die Entwicklung chiraler Liganden zur Kontrolle der Regio-, Diastereo- und Enantioselektivität. Dabei haben sich Phosphoramidite als eine äußerst vielseitige und leicht zugängliche Klasse von chiralen Liganden erwiesen. Ihre modulare Struktur ermöglicht die Herstellung von Ligandenbibliotheken und erleichtert die Feinabstimmung für eine bestimmte katalytische Reaktion. Phosphoramidite bewirken oft außerordentlich hohe Stereoselektivitäten, und ihre einzähnige Natur ist in der kombinatorischen Katalyse, die gemischte Liganden verwendet, unverzichtbar. In diesem Aufsatz werden neue Entwicklungen in der asymmetrischen Katalyse mit Phosphoramiditen diskutiert, wobei der Schwerpunkt auf der Bildung von Kohlenstoff- Kohlenstoff- und Kohlenstoff-Heteroatom-Bindungen liegt. [source] Catalytic Asymmetric Conjugate Addition of Nitroalkanes to 4-Nitro-5-styrylisoxazoles,ANGEWANDTE CHEMIE, Issue 49 2009Andrea Baschieri Zweimal Nitro: 4-Nitro-5-styrylisoxazole dienten als maskierte ,,,-ungesättigte Carbonsäuren in der katalytischen asymmetrischen Titelreaktion. Der 4-Nitroisoxazolkern aktiviert das konjugierte Alken und eine latente Carboxylatfunktion. Die Reaktion läuft mit 5,Mol-% eines einfach zugänglichen Phasentransferkatalysators bei Raumtemperatur mit bemerkenswerter Diastereo- und Enantioselektivität ab (siehe Schema). [source] Enantioselective One-Pot Organocatalytic Michael Addition/Gold-Catalyzed Tandem Acetalization/Cyclization,ANGEWANDTE CHEMIE, Issue 47 2009Sébastien Belot (An)organokatalytische Reaktion: Eine Sequenz aus einer Michael-Addition an ein Nitroenin und einer Acetalisierung/Cyclisierung (siehe Schema; TMS=Trimethylsilyl) liefert nitrosubstituierte Tetrahydrofuranylether mit hoher Diastereo- und Enantioselektivität. Organokatalyse und Goldkatalyse sind bei diesem Eintopfprozess kompatibel und komplementär. [source] Stereocontrolled Synthesis of Carbon Chains Bearing Contiguous Methyl Groups by Iterative Boronic Ester Homologations: Application to the Total Synthesis of (+)-Faranal,ANGEWANDTE CHEMIE, Issue 34 2009Guillaume Dutheuil Dr. ,Ketten"-Reaktionen: Durch vierfache Homologisierung eines Boronsäureesters lässt sich ein einfaches Vinyliodid mit hoher Diastereo- und Enantioselektivität in eine komplexe Faranalvorstufe umwandeln. Auf diesem Weg kann (+)-Faranal in nur sechs Stufen und mit einer Gesamtausbeute von 18,% aus Propin hergestellt werden. [source] Enantioselective Organocatalytic Domino Oxa-Michael/Aldol/Hemiacetalization: Synthesis of Polysubstituted Furofuranes Containing Four Stereocenters,ANGEWANDTE CHEMIE, Issue 31 2009Efraím Reyes Prof. Drei auf einmal: Die Titelverbindungen sind in einem einzigen Schritt ausgehend von ,,,-ungesättigten Aldehyden und dem Dihydroxyacetondimer mithilfe eines chiralen sekundären Amins als Katalysator zugänglich (siehe Schema, TMS=Trimethylsilyl). Die ablaufende Reaktionsfolge erzeugt vier stereogene Zentren und liefert die bicyclischen Verbindungen in guten Ausbeuten und mit ausgezeichneten Diastereo- und Enantioselektivitäten. [source] Copper-Catalyzed Diastereo- and Enantioselective Sequential Reactions of Propargylic Acetates with (E)-2,4-PentadienylamineCHEMCATCHEM, Issue 2 2010Gaku Hattori Natural selection: The copper-catalyzed diastereo- and enantioselective sequential reactions of propargylic acetates with (E)-2,4-pentadienylamine give the corresponding 1,2-disubstituted tetrahydroisoindoles in high yields with high diastereo- and enantioselectivities, in which only a single copper works as a catalyst to promote both steps: the propargylic amination and intramolecular [4+2] cycloaddition. [source] ChemInform Abstract: Efficient Diastereo- and Enantioselective Synthesis of ,,,-Disubstituted ,-Phosphono SulfonatesCHEMINFORM, Issue 20 2010Dieter Enders 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: Diastereo- and Enantioselective Direct Henry Reaction of Pyruvates Mediated by Chiral P-Spiro Tetraaminophosphonium Salts.CHEMINFORM, Issue 15 2010Daisuke Uraguchi 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: Highly Diastereo- and Enantioselective Pd-Catalyzed Cyclopropanation of Acyclic Amides with Substituted Allyl Carbonates.CHEMINFORM, Issue 48 2009Wei Liu 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: Diastereo- and Enantioselective Synthesis of ,-Hydroxy-,-Amino Acids: Application to the Synthesis of a Key Intermediate for Lactacystin.CHEMINFORM, Issue 27 2009Qiong Li 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 Regio-, Diastereo-, and Enantioselective [2 + 2 + 2] Cycloaddition of 1,6-Enynes with Electron-Deficient Ketones Catalyzed by a Cationic Rh(I)/H8 -binap Complex.CHEMINFORM, Issue 24 2008Ken Tanaka 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] Diastereo- and Enantioselective Synthesis of ,,,-Epoxyketones Using Aqueous NaOCl in Conjunction with Dihydrocinchonidine Derived Phase-Transfer Catalysis at Room Temperature.CHEMINFORM, Issue 47 2007Limitations., Scope 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 Diastereo- and Enantioselective Direct Aldol Reactions of Cycloketones with Aldehydes Catalyzed by a trans-4-tert-Butyldimethylsiloxy-L-proline Amide.CHEMINFORM, Issue 27 2007Long He 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] Combined Proline,Surfactant Organocatalyst for the Highly Diastereo- and Enantioselective Aqueous Direct Cross-Aldol Reaction of Aldehydes.CHEMINFORM, Issue 50 2006Yujiro Hayashi 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 Diastereo- and Enantioselective Copper-Catalyzed Domino Reduction/Aldol Reaction of Ketones with Methyl Acrylate.CHEMINFORM, Issue 24 2006Julia Deschamp 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] Bifunctional-Thiourea-Catalyzed Diastereo- and Enantioselective aza-Henry Reaction.CHEMINFORM, Issue 20 2006Xuenong Xu 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] Development of a New Dimeric Cyclophane Ligand: Application to Enhanced Diastereo- and Enantioselectivity in the Catalytic Synthesis of ,-Lactams.CHEMINFORM, Issue 42 2004Harald Wack Abstract For Abstract see ChemInform Abstract in Full Text. [source] Diastereo- and Enantioselective Synthesis of 1,-C-Branched N,O-NucleosidesCHEMINFORM, Issue 4 2004M. G. Saita Abstract For Abstract see ChemInform Abstract in Full Text. [source] Diastereo- and Enantioselective Intramolecular [2+2],Photocycloaddition Reactions of 3-(,,-Alkenyl)- and 3-(,,-Alkenyloxy)-Substituted 5,6-Dihydro-1H -pyridin-2-onesCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2010Dominik Albrecht Dr. Abstract 3-(,,-Alkenyl)-substituted 5,6-dihydro-1H -pyridin-2-ones 2,4 were prepared as photocycloaddition precursors either by cross-coupling from 3-iodo-5,6-dihydro-1H -pyridin-2-one (8) or,more favorably,from the corresponding ,-(,,-alkenyl)-substituted ,-valerolactams 9,11 by a selenylation/elimination sequence (56,62,% overall yield). 3-(,,-Alkenyloxy)-substituted 5,6-dihydro-1H -pyridin-2-ones 5 and 6 were accessible in 43 and 37,% overall yield from 3-diazopiperidin-2-one (15) by an ,,,-chloroselenylation reaction at the 3-position followed by nucleophilic displacement of a chloride ion with an ,-alkenolate and oxidative elimination of selenoxide. Upon irradiation at ,=254,nm, the precursor compounds underwent a clean intramolecular [2+2] photocycloaddition reaction. Substrates 2 and 5, tethered by a two-atom chain, exclusively delivered the respective crossed products 19 and 20, and substrates 3, 5, and 6, tethered by longer chains, gave the straight products 21,23. The completely regio- and diastereoselective photocycloaddition reactions proceeded in 63,83,% yield. Irradiation in the presence of the chiral templates (,)- 1 and (+)- 31 at ,75,°C in toluene rendered the reactions enantioselective with selectivities varying between 40 and 85,%,ee. Truncated template rac - 31 was prepared as a noranalogue of the well-established template 1 in eight steps and 56,% yield from the Kemp triacid (24). Subsequent resolution delivered the enantiomerically pure templates (,)- 31 and (+)- 31. The outcome of the reactions is compared to the results achieved with 4-substituted 5,6-dihydro-1H -pyridin-2-ones and quinolones. [source] Solvent-Enhanced Diastereo- and Regioselectivity in the PdII -Catalyzed Synthesis of Six- and Eight-Membered Heterocycles via cis -AminopalladationCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2009Árpád Balázs Abstract The PdII -catalyzed intramolecular oxidative cyclization of tosyl-protected cis- and trans - N -allyl-2-aminocyclohexanecarboxamides was examined, and efficient syntheses of cyclohexane-fused pyrimidin-4-ones and 1,5-diazocin-6-ones were developed. In the course of the research, a marked solvent effect was observed on both the regio- and diastereoselectivity. Additionally, a novel PdII -mediated domino oxidation, oxidative amination reaction was discovered. Our experimental and theoretical findings suggest that the reactions proceed via a cis -aminopalladation mechanism. [source] Bifunctional-Thiourea-Catalyzed Diastereo- and Enantioselective Aza-Henry ReactionCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2006Xuenong Xu Dr. Abstract Bifunctional thiourea 1,a catalyzes aza-Henry reaction of nitroalkanes with N -Boc-imines to give syn -,-nitroamines with good to high diastereo- and enantioselectivity. Apart from the catalyst, the reaction requires no additional reagents such as a Lewis acid or a Lewis base. The N-protecting groups of the imines have a determining effect on the chirality of the products, that is, the reaction of N -Boc-imines gives R adducts as major products, whereas the same reaction of N -phosphonoylimines furnishes the corresponding S adducts. Various types of nitroalkanes bearing aryl, alcohol, ether, and ester groups can be used as nucleophiles, providing access to a wide range of useful chiral building blocks in good yield and high enantiomeric excess. Synthetic versatility of the addition products is demonstrated by the transformation to chiral piperidine derivatives such as CP-99,994. [source] Diastereo- and Enantioselective Reductive Aldol Reaction with Trichlorosilane Using Chiral Lewis Bases as OrganocatalystsCHEMISTRY - AN ASIAN JOURNAL, Issue 3 2010Masaharu Sugiura Prof. Chiral Lewis base organocatalysts activate trichlorosilane to promote the tandem conjugate reduction/aldol reaction of ,,,-unsaturated ketones with aldehydes to give optically active ,-hydroxy ketones with good to high syn diastereo- and enantioselectivities. The reaction tolerates ,,,-unsaturated aldehydes owing to the chemoselective conjugate reduction of enones in the presence of enals. [source] Asymmetric Synthesis of ,,,-Substituted ,-Sultones via Allylation of Chiral Lithiated SulfonatesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2003Dieter Enders Abstract The first auxiliary controlled asymmetric synthesis of enantiopure ,,,-substituted ,-sultones via ,-allylation of lithiated sulfonates by using 1,2:5,6-di- O -isopropylidene-,- D -allofuranose as chiral auxiliary is described. The high asymmetric inductions of the ,-allylations were reached in good to excellent yields. Successive epimerization-free cleavage of the auxiliary and diastereoselective ring closure of the sulfonic acid intermediates in a one-pot procedure led to the title compounds in good to excellent yields and diastereo- and enantiomeric excesses (de, ee , 98%). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Simple Chiral Diaminobinaphthyl Dilithium Salts for Intramolecular Catalytic Asymmetric Hydroamination of Amino-1,3-dienesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Julia Deschamp Abstract Simple and easily accessible chiral lithium amide salts are reported as efficient (pre)catalysts for the diastereo- [up to (E:Z)=92:8] and enantioselective [up to 72% ee (E)] hydroamination/cyclisation of conjugated primary aminodienes. These chiral lithium salts are straightforwardly prepared by in situ combination of an N -substituted (R)-(+)-1,1,-binaphthyl-2,2,-diamine ligand and a commercial methyllithium solution. Information on the solid-state structure of these salts was obtained by X-ray analysis of a single crystal. [source] Catalytic, Asymmetric Vinylogous Mukaiyama Aldol Reactions of Pyrrole- and Furan-Based Dienoxy Silanes: How the Diene Heteroatom Impacts StereocontrolADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Claudio Curti Abstract Denmark's chiral bisphosphoramide/silicon tetrachloride system performs as an excellent Lewis base-Lewis acid catalyst for the vinylogous Mukaiyama aldol reaction of pyrrole- and furan-based dienoxy silanes with aromatic and heteroaromatic aldehydes. This asymmetric methodology provides a powerful synthetic entry to a variety of ,-hydroxylated ,-butenolide-type frameworks with high efficiency and valuable margins of regio-, diastereo-, and enantioselectivity. Notably, the nature of the heteroatom within the vinylogous dienoxy silane donor heavily impacts the diastereocontrol, with syn -configured aldol adducts emerging from pyrroles bearing electron-withdrawing N -protecting groups (Boc, Ts, and Cbz) and anti -configured adducts prevailing when furan- or N -alkyl/alkenylpyrrole donors are involved. [source] | ||||||||||||||||||||||