Chiral anion-mediated asymmetric ring opening of meso-aziridinium and episulfonium ions.
J Am Chem Soc
; 130(45): 14984-6, 2008 Nov 12.
Article
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| MEDLINE
| ID: mdl-18937464
ABSTRACT
Reactions proceeding through cationic intermediates that lack a Lewis or Brønsted basic site present a challenge for traditional asymmetric catalysis based on chiral metals or organocatalysts. We present an enantioselective ring opening of tetrasubstituted meso-aziridinium ions with alcohol nucleophiles proceeding through a chiral ion pair with a binaphthol-phosphate anion. The reaction is initiated by silver-induced ring closure of beta-chloroamines using the Ag salt of the chiral anion as in situ generated catalyst. Use of insoluble Ag2CO3 as silver source is essential to obtain high enantioselectivity; we believe the chiral phosphate acts as a "chiral anion phase transfer catalyst" to bring silver ion into the organic phase. The chiral anion concept can also be extended to the related asymmetric opening of meso-episulfonium ions generated by protonation of trichloroacetimidates vicinal to sulfides.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Compuestos de Sulfonio
/
Aziridinas
Idioma:
En
Revista:
J Am Chem Soc
Año:
2008
Tipo del documento:
Article
País de afiliación:
Estados Unidos