Application of chiral cationic catalysts to several classical syntheses of racemic natural products transforms them into highly enantioselective pathways.
J Am Chem Soc
; 126(42): 13708-13, 2004 Oct 27.
Article
de En
| MEDLINE
| ID: mdl-15493929
ABSTRACT
This paper describes the application of chiral oxazaborolidinium cations of type 2 to various enantioselective Diels-Alder reactions that have served as early key steps for the syntheses of complex natural products. In the original syntheses these Diels-Alder reactions produced racemic adducts and led to racemic target molecules unless a separation of enantiomers by classical resolution was employed. By use of chiral catalysts of type 2, chiral products were obtained directly from Diels-Alder reactions of achiral components in excellent yield and enantioselectivity and with the mechanistically predicted absolute configuration. As a result, a number of classical syntheses could be converted to enantioselective versions, including (1) cortisone/cortisol (Merck/Sarett), (2) dendrobine (Kende), (3) vitamin B(12) (Eschenmoser), (4) myrocin C (Chu-Moyer/Danishefsky), (5) coriolin and hirsutene (Mehta), (6) dendrobatid 251F (Aube), (7) silphinene (Ito), and (8) nicandrenone core (Stoltz/Corey).
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Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Produits biologiques
/
Composés du bore
Langue:
En
Journal:
J Am Chem Soc
Année:
2004
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique