A5018036356- Asymmetric Synthesis and Catalysis
- Synthetic Organic Chemistry Methods
- Chemical Synthesis and Analysis
- Catalytic C–H Functionalization Methods
- Radical Photochemical Reactions
- Cyclopropane Reaction Mechanisms
- Synthesis and Catalytic Reactions
- Chemical synthesis and alkaloids
- Oxidative Organic Chemistry Reactions
- Organometallic Complex Synthesis and Catalysis
- Fluorine in Organic Chemistry
- Chemistry and Chemical Engineering
- Catalytic Alkyne Reactions
- Synthesis and Reactions of Organic Compounds
- Biomedical and Chemical Research
- Sulfur-Based Synthesis Techniques
- Advanced Synthetic Organic Chemistry
- Recycling and Waste Management Techniques
- Organic Chemistry Cycloaddition Reactions
- Alkaloids: synthesis and pharmacology
- Marine Toxins and Detection Methods
- Synthesis of β-Lactam Compounds
- Polyoxometalates: Synthesis and Applications
- Click Chemistry and Applications
- Ferrocene Chemistry and Applications
Environment Agency Austria
2022
Heinrich Heine University Düsseldorf
2015-2020
Forschungszentrum Jülich
2017-2020
Aarhus University
2010-2012
University of Bonn
2006-2010
University of Helsinki
2008
University of Cologne
2008
The mechanisms of the α-, β- and γ-functionalisations aldehydes α,β-unsaturated by secondary amines are presented discussed.
Phosphines go one-pot: The one-pot synthesis of cyclic α-amino esters from azlactones and allenes by a phosphine-catalyzed [3+2]-cycloaddition reaction followed ring opening the azlactone moiety is presented. products are isolated as single regioisomers in good overall yields high enantioselectivities (up to 95 % ee). possibility for easy modifications obtained was demonstrated synthesizing an amino acid α-hydroxy-β-ketoester. Phosphine-catalyzed reactions electron-deficient alkynes with...
A method for the preparation of a variety cyclobutanes via 4-exo cyclization radicals is presented. Radical generation carried out by electron transfer from titanocene(III) chlorides to epoxides. The reaction relies on acceleration through use α,β-unsaturated carbonyl compounds as radical traps and thermodynamic stabilization cyclobutylcarbinyl conjugation. mechanism transformation was investigated combined theoretical experimental study. computational results provide crucial energetic...
Small rings through large templates: A two-point binding of the substrate radicals to cationic titanocene templates is essential for success otherwise impossible 4-exo cyclizations (see scheme; Bn=benzyl). The cyclobutanes are obtained in high stereoselectivity and can be additionally functionalized a straightforward manner. Detailed facts importance specialist readers published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available...
An elegant sequence: efficient method for the formation of octahydroacridines provides high yields and a level stereogenic control, displays great tolerance towards different aldehydes, anilines, nucleophiles (see scheme; TMS=trimethylsilyl; EWG=electron-withdrawing group). The use verifies an endo transition state in which π–π overlap aromatic rings plays important role reactivity selectivity.
The development of highly enantio- and diastereoselective organocatalytic monofluorovinylations is presented. Based on the application α-fluoro-β-keto-benzothiazolesulfones, formal addition a monofluorovinylic anion synthon to range acyclic cyclic enones, as well imines, shown. These procedures give selective access both E- Z-isomers monofluorovinylated products, which are isolated pure diastereoisomers in good excellent yields with up 99% ee. Furthermore, this concept for formation...
Abstract Many biologically active substances are composed of sesquiterpene units linked to aromatic structures, especially substituted phenols. Here, we describe an efficient synthetic approach this class natural product from commercially available in a short sequence. The key transformations involve allylic substitution reactions using palladium or copper catalyst and titanocene‐catalyzed epoxypolyene cyclization via radicals. polycyclic core structures accessed with high chemo‐...
Abstract An asymmetric bio‐ and organocatalytic cascade one‐pot reaction for the α‐arylation of aldehydes is presented. 1,4‐Dihydroxybenzene its derivatives are oxidized to quinones by laccase aerial oxygen. This catalytic process has been efficiently coupled enamine organocatalysis, affording 3‐substituted 2,3‐dihydrobenzofuran‐2,5‐diols in moderate good yield excellent enantioselectivity. magnified image
A modular approach to carbonyl-functionalized titanocenes is described. Through the introduction of highly electrophilic acid chlorides complexes, reactions with nucleophiles can be realized that are incompatible classical methods titanocene synthesis. The first amino functionalized were synthesized. amide- and ketone-functionalized cationic, due complexation carbonyl groups results in formation unstrained rings.
A chiral, ammonium ylide based access to tetrasubstituted 2,3‐dihydrofurans starting from readily available benzylidene dicarbonyls and bromo acetophenones has been developed. The products are obtained in moderate good yields with excellent diasteroselectivity enantioselectivity (up 99:1 e.r.). employed chiral amine can be recovered near quantitative yield. transformation run as a three‐component one‐pot reaction, generating the salt situ. scope of this reaction includes 17 new dihydrofurans...
A new class of titanocene complexes such as depicted displays very high induction apoptosis and hence selectivity against leukemia tumor cells. First in vivo experiments (see graphic) exhibit significant inhibition growth. The correlation biological activity with structural elements suggests the first design principles for cytotoxicity titanocenes. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2111/2008/z800407_s.pdf or from author. Please...
Elegante Sequenz: Eine effiziente Methode für die Bildung von Octahydroacridinen liefert hohe Ausbeuten und Stereoselektivitäten kann auf ein breites Spektrum Aldehyden, Anilinen Nucleophilen angewendet werden (siehe Schema; TMS=Trimethylsilyl; EWG=elektronenziehende Gruppe). Die Anwendung verschiedener Nucleophile offenbart einen endo-Übergangszustand, in dem eine π-π-Überlappung der aromatischen Ringe wichtige Rolle Reaktivität Selektivität spielt. Detailed facts of importance to...
Kleine Ringe durch große Template: Die Zwei-Punkt-Anbindung des Radikals an das kationische Templat ist für den Erfolg einer sonst unmöglichen 4-exo-Cyclisierung entscheidend (siehe Schema; Bn=Benzyl). Es werden mit hoher Stereoselektivität Cyclobutane erhalten, die sich auf einfache Weise weiter funktionalisieren lassen.
Highly stereoselective one-pot syntheses of various optically active N-heterocyclic bicycles have been developed. The protocols are based on an organocatalytic, asymmetric Michael addition followed by a condensation/cycloaddition sequence to furnish aziridine carbonyls, β-lactams, or octahydrobenzo[c]isoxazoles depending the reaction conditions and applied nucleophiles.
A short synthesis of sclareol oxide from epoxyfarnesyl acetone in six steps is described. The strategy features a titanocene-catalyzed epoxypolyene cyclization for the construction carbocyclic core structure. exo olefin formed during termination essential ensuing functional group modification that results preparation dihydropyran.
Abstract An ammonium ylide mediated access towards trans‐β,γ ‐disubstituted, all‐trans ‐ α,β,γ ‐trisubstituted, and α,α,β,γ ‐tetrasubstituted γ ‐butyrolactones bearing a broad variety of functionalities was developed. Starting from widely accessible benzylidene Meldrum's acid derivatives α‐ bromo carbonyl compounds, were obtained in yields between 32–99% with up to excellent diastereoselectivities (>95:5) via DABCO‐mediated [2+1] annulation. Utilization enantiomerically pure cinchona...
A modular approach to bench-stable titanocene enolates is described. The reaction of titanocenes containing pendent acid chlorides with activated methylene compounds in the presence excess base results formation pivotal enolates. In all cases, are coordinated titanocene, which acts as a stabilizing template an intramolecular manner, demonstrated by NMR spectroscopy and X-ray crystallography. Upon protonation strong acids, C−C bond formed during acylation cleaved. Hence, effect can be...
Abstract Depending on catalyst and reducing agent used, selective formation of (R)‐ or (S)‐ (E)‐ (Z)‐configurated products is possible.
Abstract Neuartiges Luciferin — enantioselektive Photoreaktionen Homogenkatalyse: Selektivitäten und Intermediate verringerte NMR‐Probenmengen repetitive Zellwand‐Polysaccharide funktionale Nanostrukturen
Abstract Siliciumrhodaminderivate weisen Formaldehyd nach – neues Nanomaterial: Graphitphasen polymeren Kohlenstoffnitrids molekulare Drähte homogene Cof-Dünnschichten bei Raumtemperatur Biosyntheserekord: 1,8 MDa großes kolGen [3,3]-sigmatrope Umlagerung führt zu quartären Stereozentren.