Total syntheses of ent-heliespirones A and C.
J Org Chem
; 77(1): 379-87, 2012 Jan 06.
Article
em En
| MEDLINE
| ID: mdl-22074003
ABSTRACT
Stereodivergent total syntheses of ent-heliespirone A and C were both completed in 11 vessels and â¼24% combined overall yield (A + C). These syntheses employed an identical inverse demand Diels-Alder reaction between a surrogate for an extendedly conjugated γ-δ unsaturated ortho-quinone methide and L-lactic-acid-derived exocyclic enol ether. Novel reactions of special note include a diastereoselective reduction of a chroman spiroketal by combination of borontrifluoride etherate and triethyl silane, along with oxidative rupture of a chroman etherial ring into the corresponding p-quinone by argentic oxide (AgO). In addition, an unusual intramolecular etherification of a 3° alcohol caused by cerium ammonium nitrate was observed.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Quinonas
/
Sesquiterpenos
/
Silanos
/
Benzoquinonas
/
Cromanos
/
Indolquinonas
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article