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The Control of the Nitrogen Inversion in Alkyl‐Substituted Diaziridines
Author(s) -
Trapp O.,
Schurig V.,
Kostyanovsky R. G.
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305494
Subject(s) - chemistry , enantioselective synthesis , enantiomer , gas chromatography , nitrogen , alkyl , analytical chemistry (journal) , elution , nitrogen inversion , computational chemistry , stereochemistry , chromatography , catalysis , organic chemistry
Abstract For the first time the nitrogen inversion barriers in 3,3‐unsubstituted trans ‐diaziridines, such as 1,2‐di‐ tert ‐butyldiaziridine ( 1 ) and 1,2‐di‐ n ‐butyldiaziridine ( 2 ) were determined. Enantioselective stopped‐flow multidimensional gas chromatography was used to investigate the enantiomerization barrier of 1 between 126.2 and 171.0 °C (Δ G ${{{\ne}\hfill \atop {\rm gas}\hfill}}$ (150.7 °C) = 135.8±0.2 kJ mol −1 , Δ H ${{{\ne}\hfill \atop {\rm gas}\hfill}}$ = 116.1±2.5 kJ mol −1 , Δ S ${{{\ne}\hfill \atop {\rm gas}\hfill}}$ = −46±2 J K −1 mol −1 ). The separation of the enantiomers has been achieved in presence of the chiral stationary phase (CSP) Chirasil‐ β ‐Dex with a high separation factor ( α = 1.44 at 80 °C). In a complementary approach, the enantiomerization barriers of 1,2‐di‐ tert‐ butyldiaziridine ( 1 ), 1,2‐di‐ n ‐butyldiaziridine ( 2 ), 1‐ n ‐butyl‐3,3‐dimethyldiaziridine ( 3 ), and 1,2,3,3‐tetramethyldiaziridine ( 4 ) were determined for comparison by enantioselective dynamic chromatography (DGC) and computer simulation of the dynamic elution profiles. The enantiomerization barrier of 2 was shown to be the highest among the nonsterically hindered diaziridines studied so far, whereas 1 exhibited the highest value found for strained nitrogen‐containing rings, that is, aziridines, diaziridines and oxaziridines.