3-Hydroxy-4-pyrones as Precursors of 4-Methoxy-3-oxidopyridinium Ylides. An Expeditious Entry to Highly Substituted 8-Azabicyclo[3.2.1]octanes.
3-Hydroxy-4-pyridones, which are easily prepared from commercially available 3-hydroxy-4-pyrones, can be readily transformed into 4-methoxy-3-oxidopyridinium ylides by treatment with methyl trifluoromethanesulfonate and subsequent deprotonation with a non-nucleophilic base. These ylides are capable of undergoing cycloaddition to several electron-deficient alkenes, thus allowing the synthesis of highly functionalized azabicyclo[3.2.1]octane moieties. The rich substitution patterns of these frameworks might allow their divergent conversion to a variety of natural and non-natural tropane alkaloids.
Rumbo
Antonio
A
Departamento de Química Orgánica y Sección de Alcaloides del CSIC, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain.
Mouriño
Antonio
A
Castedo
Luis
L
Mascareñas
José L.
JL