Scientific article

Chiral Concave Imidazolinium Salts as Precursors to Chiral Concave N-Heterocyclic Carbenes

Published inEuropean journal of organic chemistry, no. 22, p. 3687-3697
Publication date2007

Imidazolinium moieties have been incorporated into bimacrocycles to generate precursors for concave N-heterocyclic carbenes (NHCs). By using one symmetrically substituted benzene bridgehead and one naphthalene bridgehead devoid of local C2-symmetry, axially chiral concave imidazolinium ions have been obtained. Starting from 2,7-dihydroxy-1-nitronaphthalene (7), the phenol groups have been transformed to 4-pentenyl ethers 8, and the nitro group was then reduced to the corresponding amine 9. Next, 9 and a 2,6-bis(alkenyloxy)aniline 10 were connected by an oxalic acid linker. After reduction of the diamide 13 to diamine 14, a bridge was installed with triethyl orthoformate to give a tetraalkenyl-substituted imidazolinium salt 15. Ring-closing metathesis of 15 followed by hydrogenation of the products 16 yielded the bimacrocyclic salts 17 in 9-18 % overall yield (based on 7), giving amounts up to >300 mg. The configurational stability of 17 was investigated by NMR using chiral enantiopure anions TRISPHAT 18 and BINPHAT 19 as stereodynamic probes.

  • Axial chirality
  • Carbenes
  • Chiral anions
  • Macrocycles
  • NMR enantiodifferentiation
  • Supramolecular chemistry
Citation (ISO format)
WINKELMANN, Ole et al. Chiral Concave Imidazolinium Salts as Precursors to Chiral Concave N-Heterocyclic Carbenes. In: European journal of organic chemistry, 2007, n° 22, p. 3687–3697. doi: 10.1002/ejoc.200700206
Updates (1)
ISSN of the journal1099-0690

Technical informations

Creation06/21/2010 10:27:29 AM
First validation06/21/2010 10:27:29 AM
Update time03/14/2023 3:46:30 PM
Status update03/14/2023 3:46:30 PM
Last indexation10/18/2023 9:33:03 AM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack