Catalysts by the meter: rapid screening approach of N-heterocyclic carbeneligand based catalysts

Lang, Carolin; Gärtner, Ute; Trapp, Oliver

doi:10.1039/c0cc02306j

Cited by 23 publications

(21 citation statements)

References 39 publications

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“…[27][28][29] Die Wahl der spektralen Bereiche der Einzelmoleküldetektion legt nahe, dass die beobachtete spektrale Verschiebung der Umwandlung der Doppelbindung in 3 zum Epoxid 4 entspricht (Abbildung 2 c,d). [27][28][29] Die Wahl der spektralen Bereiche der Einzelmoleküldetektion legt nahe, dass die beobachtete spektrale Verschiebung der Umwandlung der Doppelbindung in 3 zum Epoxid 4 entspricht (Abbildung 2 c,d).…”

Section: Angewandte Zuschriftenunclassified

Direkte Beobachtung alternativer Reaktionswege an einzelnen Molekülen

et al. 2013

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Wir danken der Deutschen Forschungsgemeinschaft (DFG) für finanzielle Unterstützung (EXC81, SFB623), Stephen Hashmi (Universität Heidelberg) für hilfreiche Diskussionen, Volker Huch für die rçntgenkristallographische Charakterisierung sowie Michael Schwering und Dominik Brox, die das Projekt mit ihrem Fachwissen in Mikroskopie unterstützt haben. Hintergrundinformationen zu diesem Beitrag sind im WWW unter

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Section: Angewandte Zuschriftenunclassified

Direkte Beobachtung alternativer Reaktionswege an einzelnen Molekülen

et al. 2013

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“…This information is important to design efficient flow-through experiments and to scale-up a reaction in a continuous process [5–9], which is often the first step for large-scale production. We contributed to this research field by developing on-column reaction chromatography, a technique where a catalytically active separation phase is used to perform (catalyzed) reactions and separations at the same time [10–17]. Here, the catalyst is immobilized or dissolved in an inert stationary phase and coated on the inside of fused-silica capillaries, which are then installed in a gas chromatograph (Fig.…”

Section: Introductionmentioning

confidence: 99%

Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

Stockinger¹,

Trapp

2013

Beilstein J. Org. Chem.

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SummaryA new approach for the investigation of a higher-order reaction by on-column reaction gas chromatography is presented. The reaction and the analytical separation are combined in a single experiment to investigate the Diels–Alder reaction of benzenediazonium-2-carboxylate as a benzyne precursor with various anthracene derivatives, i.e. anthracene, 9-bromoanthracene, 9-anthracenecarboxaldehyde and 9-anthracenemethanol. To overcome limitations of short reaction contact times at elevated temperatures a novel experimental setup was developed involving a cooling trap to achieve focusing and mixing of the reactants at a defined spot in a fused-silica capillary. This trap functions as a reactor within the separation column in the oven of a gas chromatograph. The reactants are sequentially injected to avoid undefined mixing in the injection port. An experimental protocol was developed with optimized injection intervals and cooling times to achieve sufficient conversions at short reaction times. Reaction products were rapidly identified by mass spectrometric detection. This new approach represents a practical procedure to investigate higher-order reactions at an analytical level and it simultaneously provides valuable information for the optimization of the reaction conditions.

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“…To improve the thermal stability and, in particular, to decrease leaching, the chiral metal-containing selector can be bonded to a polymeric backbone, a strategy commonly used to immobilize catalysts; [36][37][38] this was first achieved by Schurig et al [39] by bonding selectors to hydridodimethylpolysiloxane (HMPS) by Pt-catalyzed hydrosilylation. Similar to related systems, [37,41,42] the development of a selector-to-support spacer of a well-defined length proved to be a key to enhanced efficiency and enantioselectivity. The pivotal step of the immobilization strategy used by Schurig et al [39] was the synthesis of 10-methylenecamphor, which required equimolar amounts of diazomethane [40] and thus limited large-scale synthesis of chiral stationary phases for preparative separations.…”

Section: Introductionmentioning

confidence: 99%

Straightforward Synthesis of Poly(dimethylsiloxane) Phases with Immobilized (1R)‐3‐(Perfluoroalkanoyl)camphorate Metal Complexes and Their Application in Enantioselective Complexation Gas Chromatography

2012

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A straightforward synthesis of novel chiral polysiloxane‐based metal stationary phases immobilized through a propylenoxy linker (Chirasil‐Metal‐OC3) to the polymeric backbone is presented. Synthesis was accomplished in six steps with high overall yields starting from commercially available, enantiopure (+)‐(1S)‐camphorsulfonic acid. Two different approaches towards Chirasil‐Metal phases featuring either a propylenoxy or propylenthio linker used for immobilization through hydrosilylation are presented. Furthermore, a new protocol for the fluoroacylation, which is one of the key steps in the synthesis of (1R)‐3‐(perfluoroalkanoyl)camphorate metal complexes, was developed to improve the isolation and overall yield. The immobilization of (1R,4S)‐10‐(allyloxy)‐3‐(heptafluorobutanoyl)camphor – 10‐(allyloxy)‐hfbc – onto polysiloxanes as well as the incorporation of nickel(II), oxovanadium(IV), europium(III), and lanthanum(III) was characterized by FT ATR IR and NMR spectroscopy. Overall, seven different Chirasil‐Metal‐OC3 polymers with different separation properties were prepared by metal incorporation and variation of the amount of immobilized (1R,4S)‐10‐(allyloxy)‐3‐(heptafluorobutanoyl)camphor (10‐allyloxy‐hfbc: 3.5, 10.2, and 20.0 %). Their performance in enantioselective complexation gas chromatography was systematically studied and excellent enantioselectivity was found for Chirasil‐Nickel‐OC3. Separation of 29 small‐sized compounds, encompassing, among others, epoxides, substituted alkenes and alkynes as well as alcohols and amides, was achieved with high separation factors α. The synthetic strategy, enantiomer separations and thermal stability (up to 160 °C) demonstrates the versatility of the newly derived Chirasil‐Metal‐OC3 phases.

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Catalysts by the meter: rapid screening approach of N-heterocyclic carbeneligand based catalysts

Cited by 23 publications

References 39 publications

Direkte Beobachtung alternativer Reaktionswege an einzelnen Molekülen

Direkte Beobachtung alternativer Reaktionswege an einzelnen Molekülen

Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

Straightforward Synthesis of Poly(dimethylsiloxane) Phases with Immobilized (1R)‐3‐(Perfluoroalkanoyl)camphorate Metal Complexes and Their Application in Enantioselective Complexation Gas Chromatography

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