A novel software tool for high throughput measurements of interconversion barriers: DCXplorer☆

Trapp, Oliver

doi:10.1016/j.jchromb.2008.07.047

Cited by 68 publications

(69 citation statements)

References 36 publications

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“…As we were unable to suppress enantiomerization of (6)-8 during chromatographic enantioresolution, its kinetic enantiomerization parameters were calculated by DHPLC with the novel software program DCXplorer that permits quick evaluation of elution profiles of interconverting stereoisomers, utilizing the unified equation of chromatography. 31,[33][34][35][36][37][38][39][40][41] The enantiomerization and hydrolysis of three benzothiadiazine different substituted to heterocyclic moiety has been studied by sfMDHPLC and DHPLC procedures.…”

Section: Resultsmentioning

confidence: 99%

“…Accordingly, the enantiomerization rate constants were calculated by dynamic chromatography experiments (DHPLC) using DCXplorer software. 31 The program employs the unified equation of chromatography that can evaluate reaction rate constants of all kinds of first order reactions taking place during a separation process. [33][34][35][36][37][38][39][40][41] The data obtained were reported in Tables 2 and 3.…”

Section: Enantiomerization and Hydrolysis Of (6)-8mentioning

confidence: 99%

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Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiral N‐alkylbenzothiadiazine derivatives

et al. 2009

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On-column stopped flow multidimensional HPLC (sfMDHPLC) and dynamic high-performance liquid chromatography were applied to investigate the influence of alkyl substituents at the sulfonamidic and amino moieties of benzothiadiazine 1,1-dioxide derivatives on hydrolysis and enantiomerization rate constants. The data obtained indicate the presence of pyrrolo substituent at the 3,4 positions on benzothiadiazine rings inhibits the hydrolysis, whereas the enantiomerization occurs in acidic medium. Hydrolysis rates are quite similar for the two benzothiadiazines methyl substituted to nitrogen at 2- and 4-positions. Conversely, enantiomerization rate of 4-N-methyl substituted is significantly higher than 2-N-methyl substituted.

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Section: Resultsmentioning

confidence: 99%

Section: Enantiomerization and Hydrolysis Of (6)-8mentioning

confidence: 99%

Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiral N‐alkylbenzothiadiazine derivatives

et al. 2009

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“…At each temperature, K and k rot were extracted by analysing chromatograms with DCXplorer. [10] The results in Tables 2 and 3 were obtained by weighted fitting of the data to appropriate equations (see the Supporting Information).…”

Section: Methodsmentioning

confidence: 99%

Remarkably Slow Rotation about a Single Bond between an sp³‐Hybridised Carbon Atom and an Aromatic Ring without ortho Substituents

Murrison¹,

Glowacki²,

Einzinger³

et al. 2009

Chemistry A European J

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Look, no ortho substituents! A series of polycycles were prepared by using a three-component Joullié-Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured, and was highly dependent on the substitution. Rotamer half-lives of up to 21 h at 298 K were observed (see figure). Rotamers resulting from this restricted rotation were isolated for the first time.A series of polycycles was prepared by using a three-component Joullié-Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured by using, in general, variable-temperature HPLC. The rate of rotation was highly dependent on substitution and rotamer half-lives of up to 21 h at 298 K were observed. Insights into the effect of substitution on the rate of rotation were gleaned through electronic structure calculations on closely related derivatives. Rotamers resulting from restricted rotation about a bond between an sp(3)-hybridised carbon atom and a phenyl ring with no ortho substituents were isolated for the first time, and the equilibration of the separated rotamers was followed by using analytical HPLC. It was demonstrated, for the first time, that a highly hindered environment for the sp(3)-hybridised atom is sufficient for slow bond rotation about a single bond between sp(3)- and sp(2)-hybridised carbon atoms.

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“…1a and 1b. Moreover, these 59 Therefore, single elution profiles are directly integrated and evaluated in a graphical interface by zooming into the area of the interconversion profile.…”

Section: Evaluation By the Unified Equationmentioning

confidence: 99%

The stereodynamics of 1,2‐dipropyldiaziridines

et al. 2009

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N-alkylated trans-diaziridines are an intriguing class of compounds with two stereogenic nitrogen atoms which easily interconvert. In the course of our investigations of the nature of the interconversion process via nitrogen inversion or electrocyclic ring opening ring closure, we synthesized and characterized the three constitutionally isomeric diaziridines 1,2-di-n-propyldiaziridine 1, 1-isopropyl-2-n-propyldiaziridine 2, and 1,2-diisopropyldiaziridine 3 to study the influence of the substituents on the interconversion barriers. Enantiomer separation was achieved by enantioselective gas chromatography on the chiral stationary phase Chirasil-beta-Dex with high separation factors alpha (1-isopropyl-2-n-propyldiaziridine: 1.18; 1, 2-diisopropyldiaziridine: 1.24; 100 degrees C 50 kPa He) for the isopropyl substituted diaziridines. These compounds showed pronounced plateau formation between 100 and 150 degrees C, and peak coalescence at elevated temperatures. The enantiomerization barriers DeltaG(double dagger) and activation parameters DeltaH(double dagger) and DeltaS(double dagger) were determined by enantioselective dynamic gas chromatography (DGC) and direct evaluation of the elution profiles using the unified equation implemented in the software DCXplorer. Interestingly, 1-isopropyl-2-n-propyldiaziridine and 1,2-diisopropyldiaziridine exhibit similar high interconversion barriers DeltaG(double dagger) (100 degrees C) of 128.3 +/- 0.4 kJ mol(-1) and 129.8 +/- 0.4 kJ mol(-1), respectively, which indicates that two sterically demanding substituents do not substantially increase the barrier as expected for a distinct nitrogen inversion process.

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A novel software tool for high throughput measurements of interconversion barriers: DCXplorer☆

Cited by 68 publications

References 36 publications

Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiral N‐alkylbenzothiadiazine derivatives

Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiral N‐alkylbenzothiadiazine derivatives

Remarkably Slow Rotation about a Single Bond between an sp³‐Hybridised Carbon Atom and an Aromatic Ring without ortho Substituents

The stereodynamics of 1,2‐dipropyldiaziridines

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A novel software tool for high throughput measurements of interconversion barriers: DCXplorer☆

Cited by 68 publications

References 36 publications

Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiral N‐alkylbenzothiadiazine derivatives

Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiral N‐alkylbenzothiadiazine derivatives

Remarkably Slow Rotation about a Single Bond between an sp3‐Hybridised Carbon Atom and an Aromatic Ring without ortho Substituents

The stereodynamics of 1,2‐dipropyldiaziridines

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Remarkably Slow Rotation about a Single Bond between an sp³‐Hybridised Carbon Atom and an Aromatic Ring without ortho Substituents