N. De Kimpe

Reactivity of Activated versus Nonactivated 2-(Bromomethyl)aziridines with respect to Sodium Methoxide: a Combined Computational and Experimental Study

H. Goossens, K. Vervisch, S. Catak, S. Stankovic, M. D'Hooghe, F. De Proft, P. Geerlings, N. De Kimpe, M. Waroquier, V. Van Speybroeck
Journal of Organic Chemistry
76 (21), 8698-8709
2011
A1

Abstract 

The difference in reactivity between the activated 2-bromomethyl-1-tosylaziridine and the non-activated 1-benzyl-2-(bromomethyl)aziridine with respect to sodium methoxide was analyzed by means of DFT calculations within the supermolecule approach, taking into account explicit solvent molecules. In addition, the reactivity of epibromohydrin with regard to sodium methoxide was assessed as well. The barriers for direct displacement of bromide by methoxide in methanol are comparable for all three heterocyclic species under study. However, ring opening was found to be only feasible for the epoxide and the activated aziridine, and not for the non-activated aziridine. According to these computational analyses, the synthesis of chiral 2-substituted 1-tosylaziridines can take place with inversion (through ring opening/ring closure) or retention (through direct bromide displacement) of configuration upon treatment of the corresponding 2-(bromomethyl)aziridines with one equivalent of a nucleophile, whereas chiral 2-substituted 1-benzylaziridines are selectively obtained with retention of configuration (via direct bromide displacement). Furthermore, the computational results showed that explicit accounting for solvent molecules is required to describe the free energy profile correctly. To verify the computational findings experimentally, chiral 1-benzyl-2-(bromomethyl)aziridines and 2-bromomethyl-1-tosylaziridines were treated with sodium methoxide in methanol. The presented work concerning the reactivity of 2-bromomethyl-1-tosylaziridine stands in contrast to the behaviour of the corresponding 1-tosyl-2-(tosyloxymethyl)aziridine with respect to nucleophiles, which undergoes a clean ring-opening/ring-closure process with inversion of configuration at the asymmetric aziridine carbon atom.

Synthesis of 2-hydroxy-1,4-oxazin-3-ones through ring transformation of 3-hydroxy-4-(1,2-dihydroxyethyl)-β-lactams and study of their reactivity

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12th Chemistry Conference for Young Scientists
Blankenberge, Belgium
Thursday, 27 February, 2014 to Friday, 28 February, 2014

Synthesis of 2-hydroxy-1,4-oxazin-3-ones through ring transformation of 3-hydroxy-4-(1,2-dihydroxyethyl)-β-lactams and study of their reactivity

ISBN/ISSN:
Talk

Conference / event / venue 

17th Sigma-Aldrich Organic Synthesis Meeting
Blankenberge, Belgium
Thursday, 5 December, 2013 to Friday, 6 December, 2013

Reactivity of Aziridinium Salts in Different Solvents Unraveled by a Combined Theoretical and Experimental Approach

The series Topics in Heterocyclic Chemistry presents critical reviews on present and future trends in the research of heterocyclic compounds. Overall the scope is to cover topics dealing with all areas within heterocyclic chemistry, both experimental and theoretical, of interest to the general heterocyclic chemistry community. The series consists of topic related volumes edited by renowned editors with contributions of experts in the field.
Content Level » Research

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