Phase-transfer-catalyzed asymmetric acylimidazole alkylation.
Org Lett
; 9(23): 4865-8, 2007 Nov 08.
Article
en En
| MEDLINE
| ID: mdl-17944480
ABSTRACT
2-Acylimidazoles are alkylated under phase-transfer conditions with cinchonidinium catalysts at -40 degrees C with allyl and benzyl electrophiles in high yield with excellent enantioselectivity (79 to >99% ee). The acylimidazole substrates are made in three steps from bromoacetic acid via the N-acylmorpholine adduct. The catalyst is made in high purity allowing for S-product formation (6-20 h) under mild conditions, consistent with an ion-pair mechanism. The products are readily converted to useful ester products using methyltriflate and sodium methoxide, via a dimethylacylimidazolium intermediate without racemization. The process is efficient, direct, and amenable to other electrophiles and transformations that proceed through an enolate intermediate.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Imidazoles
Idioma:
En
Revista:
Org Lett
Asunto de la revista:
BIOQUIMICA
Año:
2007
Tipo del documento:
Article
País de afiliación:
Estados Unidos