Diaziridine, VII. Diaziridine aus Aminalen des Formaldehyds

Ohme, R.; Schmitz, Ernst; Dolge, Peter

doi:10.1002/cber.19660990706

Cited by 53 publications

(18 citation statements)

References 7 publications

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“…The diaziridines were prepared according to a modification of the method Ohme et al 47,54 250 mmol Alkylamine and 50 ml 5N NaOH are combined in a 250 ml flask Scheme 2. Enantiomeric pairs of (a) 1,2-di-n-propyldiazirine 1, (b) 1-isopropyl-2-n-propyldiaziridine 2, and (c) 1,2-diisopropyldiaziridine 3. equipped with a magnetic stirrer and cooled to 08C.…”

Section: Materials and Methods Generalmentioning

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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Section: Materials and Methods Generalmentioning

confidence: 99%

The stereodynamics of 1,2‐dipropyldiaziridines

et al. 2009

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“…1-n-Butyl-2-tert-butyldiaziridine was prepared by a modification of the method of Ohme et al 47 12.4 ml (125 mmol) n-Butylamine, 13.2 ml tert-butylamine and 50 ml 5N NaOH were combined in a 250 ml flask equipped with a magnetic stirrer and cooled to 08C. First, 12.5 ml formaldehyde solution (36% w/w) and then 75 ml sodium hypochlorite solution (13% w/w) were added dropwise.…”

Section: -N-butyl-2-tert-butyldiaziridinementioning

confidence: 99%

Fast and precise access to enantiomerization rate constants in dynamic chromatography

Trapp

2006

Chirality

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An analytical solution of the unified equation to evaluate elution profiles of interconverting enantiomers in dynamic chromatography is presented. Rate constants k1 and k(-1) and Gibbs activation energies are directly obtained from the chromatographic parameters (retention times tR A and tR A of the interconverting enantiomers, the peak widths at half height wA and wB, and the relative plateau height hp), and the initial amounts A0 and B0 of the enantiomers without any iterative and time consuming computational step. Therefore, this equation is no longer limited to racemic analytes. The analytical solution presented here was validated by comparison with a dataset of 125,000 simulated elution profiles of enantiomerizations. Furthermore, it was found that the recovery rate from a defined dataset is on average 40% higher using the unified equation compared to evaluation methods based on iterative computer simulation. The new equation was applied to determine the enantiomerization rate constant of 1-n-butyl-2-tert-butyldiaziridine by enantioselective gas chromatography. The activation parameters (DeltaH(double dagger) = 112.6 +/- 2.5 kJ/mol and DeltaS(double dagger) = -27 +/- 2 J/(K mol) were obtained from temperature-dependent measurements between 100 degrees C and 140 degrees C in 10K steps.

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“…In tetramezine, two diaziridine20–22 moieties are linked together by an N,N ′‐ethylene bridge. Each of the diaziridine moieties has two stereogenic nitrogen centers,20, 23 which was first recognized by Mannschreck et al24 These stereogenic nitrogen centers are stereolabile and, therefore, are prone to interconversion 21, 25. The adjacent substituents at the nitrogen atoms of the diaziridines moieties exist only in an antiperiplanar conformation, which results in a coupled interconversion 26.…”

Section: Introductionmentioning

confidence: 99%

Stereodynamics of tetramezine

Kamuf

Trapp

2010

Chirality

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The antidepressant drug tetramezine [1,2-bis-(3,3-dimethyldiaziridin-1-yl)ethane] consists of two bridged diaziridine moieties with four stereogenic nitrogen centers, which are stereolabile and, therefore, are prone to interconversion. The adjacent substituents at the nitrogen atoms of the diaziridines moieties exist only in an antiperiplanar conformation, which results in a coupled interconversion. Therefore, three stereoisomers exist (meso form and two enantiomeric forms), which epimerize when the diaziridine moieties are regarded as stereogenic units due to the coupled interconversion. Here, we have investigated the epimerization between the meso and enantiomeric forms by dynamic gas chromatography. Temperature-dependent measurements were performed, and reaction rate constants were determined using the unified equation of chromatography implemented in the software DCXplorer. The activation barriers of the epimerization were found to be ΔG(≠) = 100.7 kJ mol(-1) at 25°C and ΔG(≠) = 104.5 kJ mol(-1) at 37°C, respectively. The activation enthalpy and entropy were determined to be ΔH(≠) = 70.3 ± 0.4 kJ mol(-1) and ΔS(≠) = -102 ± 2 J mol(-1) K(-1) .

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Diaziridine, VII. Diaziridine aus Aminalen des Formaldehyds

Cited by 53 publications

References 7 publications

The stereodynamics of 1,2‐dipropyldiaziridines

The stereodynamics of 1,2‐dipropyldiaziridines

Fast and precise access to enantiomerization rate constants in dynamic chromatography

Stereodynamics of tetramezine

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