Carbene Catalyzed Access to 3,6‐Disubstituted α‐Pyrones via Michael Addition/Lactonization/Elimination Cascade

Abstract

AbstractThe first direct transition metal‐free access to 3,6‐disubstituted α‐pyrones from α‐chloro aldehydes and β‐tosyl enones is reported. The reactions proceed via the Michael addition/lactonization/elimination cascade. The regioselective addition of NHC‐bound enolates/homoenolates to the enones bearing a bulkier functionality such as tosyl group at the β‐position has remained challenging. The 3,6‐disubstituted α‐pyrones could be converted to valuable products such as 1,2,3,4‐tetrasubstituted benzenes, 1,4‐disubstituted naphthalenes as well as anthracenes and 6,13‐disubstituted dihydro‐ethenopentacenes in a simple operation.magnified image