CaRLa Catalysis Research Laboratory

Heidelberg, Germany

CaRLa Catalysis Research Laboratory

Heidelberg, Germany

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Plessow P.,BASF | Plessow P.,CaRLa Catalysis Research Laboratory
Journal of Chemical Theory and Computation | Year: 2013

This letter describes a chain-of-states method that optimizes reaction paths under the sole constraint of equally spaced structures. In contrast to NEB and string methods, it requires no spring forces, interpolation algorithms, or other heuristics to control structure distribution. Rigorous use of a quadratic PES allows calculation of an optimization step with a predefined distribution in Cartesian space. The method is a formal extension of single-structure quasi-Newton methods. An initial guess can be evolved, as in the growing string method. © 2013 American Chemical Society.


Schachner J.A.,CaRLa Catalysis Research Laboratory | Cabrera J.,CaRLa Catalysis Research Laboratory | Padilla R.,CaRLa Catalysis Research Laboratory | Fischer C.,BASF | And 5 more authors.
ACS Catalysis | Year: 2011

We report on a series of six new pyridinealkoxide-bridged first and second generation ruthenium carbenes with similar or even higher activity in ring-opening metathesis polymerization (ROMP), cross metathesis (CM), and ring closing metathesis (RCM) reactions than state-of-the-art catalysts. The new precatalysts show an extraordinarily high stickiness to commercially available silica, which significantly enhances their adsorptive separation from unprocessed reaction mixtures. © 2011 American Chemical Society.


Bru M.,CaRLa Catalysis Research Laboratory | Dehn R.,BASF | Teles J.H.,BASF | Deuerlein S.,BASF | And 4 more authors.
Chemistry - A European Journal | Year: 2013

In the search for a highly active and selective heterogenized metathesis catalyst, we systematically varied the pore geometry and size of various silica-based mesoporous (i.e., MCM-41, MCM-48, and SBA-15) and microporous (ZSM-5 and MWW) versus macroporous materials (D11-10 and Aerosil 200), besides other process parameters (temperature, dilution, and mean residence time). The activity and, especially, selectivity of such "linker-free" supports for ruthenium metathesis catalysts were evaluated in the cyclodimerization of cis-cyclooctene to form 1,9-cyclohexadecadiene, a valuable intermediate in the flavor and fragrance industry. The optimized material showed not only exceptionally high selectivity to the valuable product, but also turned out to be a truly heterogeneous catalyst with superior activity relative to the unsupported homogeneous complex. In the ring-opening/ring-closing metathesis (RO-RCM; see picture) of cis-cyclooctene, mesoporous silicas (i.e., MCM-41, MCM-48, SBA-15) are preferred supports for homogeneous ruthenium carbenes (see picture). The optimized "linker-free" support showed not only exceptionally high selectivity toward 1,9-cyclohexadecadiene, a valuable intermediate in the flavor and fragrance industry, but is also a truly heterogeneous catalyst with superior activity relative to the unsupported homogeneous complex. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wetzel A.,CaRLa Catalysis Research Laboratory | Wetzel A.,BASF | Wockel S.,CaRLa Catalysis Research Laboratory | Wockel S.,BASF | And 7 more authors.
Organic Letters | Year: 2013

[Cp*Ir(Pro)Cl] (Pro = prolinato) was identified among a series of Cp*-iridium half-sandwich complexes as a highly reactive and selective catalyst for the alkylation of amines with alcohols. It is active under mild conditions in either toluene or water without the need for base or other additives, tolerates a wide range of alcohols and amines, and gives secondary amines in good to excellent isolated yields. © 2013 American Chemical Society.


Limbach M.,CaRLa Catalysis Research Laboratory | Limbach M.,BASF
Advances in Organometallic Chemistry | Year: 2015

For more than three decades, the catalytic synthesis of acrylates from the cheap and abundantly available C1 building block CO2 and alkenes has been an unsolved problem in catalysis research, both in academia and industry. Acrylates and their downstream products are ubiquitous in daily life as hygiene products, coatings, adhesives, or plastics, etc., and they are manufactured globally on a multimillion ton level. Thus, a CO2-based route to such world-scale chemicals is economically most attractive, but, due to thermodynamic and kinetic hurdles, also highly challenging. Since the revolutionary work of Hoberg et al., metallalactones are discussed as possible intermediates in a catalytic cycle, but the reaction has not been existing until recently.Herein, we present our and others' efforts on the development of a homogeneous catalyst that permits the catalytic synthesis of salts of α,β-unsaturated acids from CO2, alkenes, and a base. As this turned out to be difficult without a deeper mechanistic understanding, we highlight most recent mechanistic findings and also elaborate on unproductive reaction pathways. © 2015 Elsevier Inc.


Cao P.,CaRLa Catalysis Research Laboratory | Cabrera J.,CaRLa Catalysis Research Laboratory | Padilla R.,CaRLa Catalysis Research Laboratory | Serra D.,CaRLa Catalysis Research Laboratory | And 3 more authors.
Organometallics | Year: 2012

Cationic platinum(II) complexes with bi- or tridentate (pincer) functionalized NHC ligands were found to be catalytically active in the hydroamination of unactivated alkenes. In some cases, the presence of water had an activating effect on the complexes. Reactions with the N-nucleophilic substrate morpholine led to a noncatalytic reaction in which the deprotonation product of the key cationic β-aminoalkyl platinum complex could be isolated and characterized. Surprisingly, attempted protonation of this complex did not give the expected N-alkylated product, indicating either the thermodynamic unfavorability of C-Pt bond cleavage or its kinetic inertness. © 2012 American Chemical Society.


Ibrahim N.,CaRLa Catalysis Research Laboratory | Vilhelmsen M.H.,University of Heidelberg | Pernpointner M.,University of Heidelberg | Rominger F.,University of Heidelberg | And 2 more authors.
Organometallics | Year: 2013

Seven different NHC gold(I) phenolate complexes were synthesized. Structural data, including X-ray crystal structure analyses, could be obtained for each of them. An investigation by computational chemistry, including NBO analysis, indicates three-center-four-electron hyperbonds among the carbene carbon, the gold atom, and the oxygen atom of the phenolate with an approximate 60:40 distribution of the bonding interaction in favor of the carbene-gold bond. The new class of complexes shows only moderate catalytic activity. © 2013 American Chemical Society.


Manzano R.,CaRLa Catalysis Research Laboratory | Rominger F.,University of Heidelberg | Hashmi A.S.K.,CaRLa Catalysis Research Laboratory | Hashmi A.S.K.,University of Heidelberg
Organometallics | Year: 2013

New saturated abnormal N-heterocyclic carbene complexes of gold(I) have been prepared by a 1,3-dipolar cycloaddition of an in situ generated azomethine ylide with an isocyanogold(I) choride. A series of different substituents on the nitrogen atom of the 1,3-dipole are tolerated without problem. Substitutents on a carbon atom of the 1,3-dipole are problematic in the case of the isocyanogold(I) chlorides; only low yields are obtained. However, the corresponding isocyanogold(I) iodide shows good reactivity, and these abnormal N-heterocyclic carbenes bear the substituent in a position α to the carbene carbon, as proven by a crystal structure analysis of one of the products. Some of the new saturated abnormal N-heterocyclic carbene complexes were then tested in the gold-catalyzed phenol synthesis; moderate turnover numbers of 252-380 could be reached. © 2013 American Chemical Society.


Manzano R.,CaRLa Catalysis Research Laboratory | Wurm T.,University of Heidelberg | Rominger F.,University of Heidelberg | Hashmi A.S.K.,CaRLa Catalysis Research Laboratory | And 2 more authors.
Chemistry - A European Journal | Year: 2014

A number of saturated abnormal N-heterocyclic carbene (NHC) complexes of gold, in combination with KBArF4 as activator, were successfully applied in the chemoselective addition of hydrazine to alkynes. The reaction proceeds even at room temperature, which was not possible to date with gold catalysts. The reaction can be applied to a number of substituted arylalkynes. With alkylalkynes the yields are low. The saturated abnormal NHC ligands are resistant to isomerization to the saturated normal NHC coordination mode under basic reaction conditions. Under acidic conditions, a simple protonation at the nitrogen atom not neighboring the carbene center was observed and unambiguously characterized by an X-ray crystal-structure analysis. Computational studies confirm that such an isomerization would be highly exothermic, the observed kinetic stability probably results from the need to shift two protons in such a process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ibrahim N.,CaRLa Catalysis Research Laboratory | Hashmi A.S.K.,CaRLa Catalysis Research Laboratory | Hashmi A.S.K.,University of Heidelberg | Rominger F.,University of Heidelberg
Advanced Synthesis and Catalysis | Year: 2011

Benzhydroles and nitriles upon gold-catalysed conversion deliver symmetrical ethers and/or N-substituted carboxylic amides. While with most phosphane ligands tested, the dominating product is always the ether, with the trimesitylene ligand the amides are the major products. The reaction conditions are much milder than those reported previously. Mechanistic control experiments with a chiral alcohol prove the intermediacy of carbenium ions, further studies with not readily ionisable alcohols indicate that for the benzhydroles the carbenium ions and gold(I)-hydroxy complexes are intermediates. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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