Total synthesis of enantiopure pyrrhoxanthin: alternative methods for the stereoselective preparation of 4-alkylidenebutenolides.
Chemistry
; 19(39): 13065-74, 2013 Sep 23.
Article
em En
| MEDLINE
| ID: mdl-23939906
ABSTRACT
A new stereocontrolled total synthesis of the configurationally labile C37 -norcarotenoid pyrrhoxanthin in enantiopure form has been completed. A highly stereoselective Horner-Wadsworth-Emmons (HWE) condensation of a C17-allylphosphonate and a C20-aldehyde was used as the last conjunctive step. Both a Sonogashira reaction to form the C17-phosphonate and the final HWE condensation proved to be compatible with the sensitive C7-C10 enyne E configuration. Regioselective (5-exo-dig) silver-promoted lactonization reactions of three alternative pent-2-en-4-ynoic acid precursors with increased complexity, including a fully functionalized C20-fragment, were explored for the preparation of the γ-alkylidenebutenolide fragment. This survey extends the existing methodologies for the preparation of oxygen-containing carotenoids (xanthophylls) and streamlines the synthesis of additional members of the C37-norcarotenoid butenolide family of natural products.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
4-Butirolactona
/
Carotenoides
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article