Thin Layer Chromatography for the Detection of Unexpected Reactions in Organometallic Combinatorial Catalysis

Lavastre, Olivier; Touzani, Rachid; Garbacia, Stefania

doi:10.1002/adsc.200303056

Cited by 21 publications

(12 citation statements)

References 29 publications

(8 reference statements)

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“…Previously, high-throughput screening (HTS) techniques have been used primarily for speeding up the optimization of Sonogashira catalysts. [21,31,56] Ideally, our approach leads to the identification of a number of quantitative steric and electronic parameters which allow the prediction of the efficiency of a given cross-coupling reaction. Notably, Fairlamb and co-workers have attempted to achieve this by evaluating the electronic properties of the modified dba (dibenzylideneacetone) type of ligands in [Pd 2 -A C H T U N G T R E N N U N G (dba) 3 ] and their effect on Suzuki and Heck cross-coupling reactions.…”

Section: Introductionmentioning

confidence: 99%

Insights into Sonogashira Cross‐Coupling by High‐Throughput Kinetics and Descriptor Modeling

Heiden

Plenio

Immel

et al. 2008

Chemistry A European J

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A method is presented for the high-throughput monitoring of reaction kinetics in homogeneous catalysis, running up to 25 coupling reactions in a single reaction vessel. This method is demonstrated and validated on the Sonogashira reaction, analyzing the kinetics for almost 500 coupling reactions. First, one-pot reactions of phenylacetylene with a set of 20 different meta- and para-substituted aryl bromides were analyzed in the presence of 17 different Pd-phosphine complexes. In addition, the temperature-dependent Sonogashira reactions were examined for 21 different ArX (X=Cl, Br, I) substrates, and the corresponding activation enthalpies and entropies were determined by means of Eyring plots: ArI (DeltaH(not equal)=48-62 kJ mol(-1); DeltaS(not equal)=-71--39 J mol(-1) K; NO(2)-->OMe), ArBr (DeltaH(not equal)=54-82 kJ mol(-1), DeltaS(not equal)=-55-11 J mol(-1) K), and ArCl (DeltaH(not equal)=95-144 kJ mol(-1), DeltaS(not equal)=-6-100 J mol(-1) K). DFT calculations established a linear correlation of DeltaH( not equal) and the Kohn-Sham HOMO energies of ArX (X=Cl, Br, I) and confirmed their involvement in the rate-limiting step. However, despite different C--X bond energies, aryl iodides and electron-deficient aryl bromides showed similar activation parameters.

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Section: Introductionmentioning

confidence: 99%

Insights into Sonogashira Cross‐Coupling by High‐Throughput Kinetics and Descriptor Modeling

Heiden

Plenio

Immel

et al. 2008

Chemistry A European J

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“…Parallel TLC with a multi-tipped needle assembly is attractive for its simplicity, thoughput, and qualitative description of selectivity and the evolution of reaction, including induction periods. [14,15] More specialized, but of much interest for both sensitivity and quantitative insight, are the gas-phase, electrospray mass spectrometry screening methods pioneered by Chen. [16][17][18] Quantitative analysis typically relies on conventional gas or highperformance liquid chromatography (GC, HPLC) to assay reaction progress and product speciation.…”

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confidence: 99%

Time as a Dimension in High‐Throughput Homogeneous Catalysis

et al. 2008

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High-throughput screening offers major opportunities to accelerate the discovery and optimization of homogeneously catalyzed reactions. A general method for acquisition of reaction profiles through a high-throughput quenching (HTQ) approach is described, which gives a more accurate picture of catalyst performance, e.g., total productivity, induction periods, selectivity and lifetime, than the customary analysis at a fixed, arbitrary time.

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“…7, where it can be seen that good resolution between the EA and I was obtained and that there were no interfering peaks. A large peak was observed at approximately 0.7 min, which was later identified to be the catalyst counter ion, BPh 4 …”

Section: Resultsmentioning

confidence: 99%

“…3 with the exception of the capillary length (21.5 cm total, 11.5 cm to detector) and injection directly from a 96-well plate. can be seen most easily by the absence of the BPh 4 2 peak at 0.7 min. From the figure, it can be seen that migration time reproducibility was excellent, with the times of EA and I within 0.9% RSD.…”

mentioning

confidence: 94%

“…Any change in catalyst precursor/product therefore requires development of a new immunoassay at considerable time and expense. Lavastre and co-workers [3,4] have utilised TLC coupled with image analysis as a quantitative screening methodology. TLC as a screening technique is widely applicable and low cost, however without the quantitative image analysis it is subject to false-positive results due to small quantities of strongly UV active products.…”

Section: Introductionmentioning

confidence: 99%

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Fast CE for combinatorial catalysis

et al. 2008

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Two solvent-modified MEKC methods were developed for the quantitative analysis of heterocyclic amines synthesised using intramolecular ring closure via catalysed hydroamination. The first method was capable of resolving six of the amines (precursors and products) with a sample-to-sample injection time of 2 min employing a 20 mM borate buffer, pH 9.2 with 20 mM SDS and 5% v/v n-butanol (n-BuOH). A second low-pH method using 20 mM phosphate buffer, 100 mm SDS, 5% v/v n-BuOH and 20% v/v iso-propanol (i-PrOH) was able to resolve an additional pair of compounds with a sample-to-sample time of 3.5 min. Application of the first method to the analysis of a sample containing catalyst as well as amines placed directly in a 96-well plate showed excellent performance, with migration time and peak height and area reproducibility being less than 0.9 and 9.6%, respectively. The quantity of conversion by catalyst was calculated to be 68 +/- 7%, which was in excellent agreement with the 67 +/- 5% obtained by more conventional (1)H NMR experiments, with the added advantage that this method is also cheaper, quicker and more amendable to high-throughput screening of combinatorial libraries.

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Thin Layer Chromatography for the Detection of Unexpected Reactions in Organometallic Combinatorial Catalysis

Cited by 21 publications

References 29 publications

Insights into Sonogashira Cross‐Coupling by High‐Throughput Kinetics and Descriptor Modeling

Insights into Sonogashira Cross‐Coupling by High‐Throughput Kinetics and Descriptor Modeling

Time as a Dimension in High‐Throughput Homogeneous Catalysis

Fast CE for combinatorial catalysis

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