Quaternary chiral β 2,2-amino acids with pyridinium and imidazolium substituents

  1. Mata, L. 1
  2. Avenoza, A. 1
  3. Busto, J.H. 1
  4. Corzana, F. 1
  5. Peregrina, J.M. 1
  1. 1 Universidad de La Rioja
    info

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

Revue:
Chemistry - A European Journal

ISSN: 0947-6539

Année de publication: 2012

Volumen: 18

Número: 49

Pages: 15822-15830

Type: Article

DOI: 10.1002/CHEM.201202096 SCOPUS: 2-s2.0-84870038619 WoS: WOS:000311438200032 GOOGLE SCHOLAR lock_openAccès ouvert editor

D'autres publications dans: Chemistry - A European Journal

Résumé

The reactions of cyclic sulfamidates as electrophiles with a variety of nitrogen-containing aromatic heterocycle nucleophiles, such as pyridines, N-alkylimidazoles and N-methylbenzimidazol, was explored. In all cases, although the nucleophilic substitution reactions occurred on quaternary centres, elimination products were not detected. The inversion of configuration at this quaternary centre was determined by X-ray diffraction analysis and the enantiomeric excess of the reactions was checked by chiral HPLC. This synthetic approach allowed us to obtain a new family of chiral charged β2,2-amino acids, including a new bisamino acid that incorporates an imidazolium salt as a cross-linker. In this context, the treatment of these chiral imidazolium salts with Ag2O opens the way to new chiral N-heterocyclic carbenes, which are important substrates in the fields of organometallic and organocatalytic chemistry. Additionally, we have done a thorough conformational analysis of these β-amino acid derivatives, both in the solid state and in solution. The most important conformational feature of these acyclic systems is the rigidity of the N-CH2-C- N+ dihedral angle, which is essentially due to the gauche effect. Chiral β2,2-amino acids: Nitrogen-containing aromatic heterocycles were used as nucleophiles in the opening reaction of cyclic sulfamidates to obtain a new family of chiral β2,2-amino acids with pyridinium and imidazolium substituents, which show a rigid N-CH 2-C-N+ dihedral angle due to the gauche effect. These chiral imidazolium derivatives open the way to the synthesis of new chiral N-heterocyclic carbenes. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.