Discovery and Development of a Three-Component Oxidopyrylium [5 + 2] Cycloaddition.
J Org Chem
; 81(9): 3744-51, 2016 05 06.
Article
em En
| MEDLINE
| ID: mdl-27018974
ABSTRACT
α-Hydroxy-γ-pyrone-based oxidopyrylium cycloaddition reactions are useful methods for accessing a highly diverse range of oxabicyclo[3.2.1]octane products. Intermolecular variants of the reaction require the formation of a methyl triflate-based pre-ylide salt that upon treatment with base in the presence of alkenes or alkynes leads to α-methoxyenone-containing bicyclic products. Herein, we describe our discovery that the use of ethanol-stabilized chloroform as solvent leads to the generation of α-ethoxyenone-containing bicyclic byproducts. This three-component process was further optimized by gently heating a mixture of a purified version of the oxidopyrylium dimer in the presence of an alcohol prior to addition of a dipolarophile. Using this convenient procedure, several new oxidopyrylium cycloaddition products can be generated in moderate yields. We also highlight the method in a tandem ring-opening/debenzylation method for the generation of α-hydroxytropolones.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pironas
/
Tropolona
/
Compostos Bicíclicos com Pontes
/
Ciclo-Octanos
/
Reação de Cicloadição
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article