Domino electrocyclization/azide-capture/schmidt rearrangement of dienones: one-step synthesis of dihydropyridones from simple building blocks.
Simple 1,4-dien-3-ones undergo Lewis acid-catalyzed Nazarov electrocyclization and intermolecular trapping by various azides to furnish 3,4-dihydropyridin-2-ones in moderate to good yields. The reaction is proposed to proceed via nucleophilic trapping of the 2-oxidocyclopentenyl intermediate, followed by Schmidt-type rearrangement to give a transient 1,4-dipole. In unsymmetrical examples, complete regioselectivity in favor of attack on the less substituted side was observed. The 1,4-dipole intermediate then rearranges to the observed dihydropyridone, via either proton transfer or 1,5-hydride shift.
Song
Dong
D
Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, Alberta, Canada T6G 2G2.
Rostami
Ali
A
West
F G
FG
D000475:Alkenes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D003500:Cyclization; D004563:Electrochemistry; D007659:Ketones / Q000737:chemistry*; D008968:Molecular Conformation; D011728:Pyridones / Q000138:chemical synthesis*