Synthesis and Rearrangement of Quinone-Embedded Epoxycyclopentenones: A New Avenue to Pyranonaphthoquinones and Indenopyranones

The epoxyquinones (e.g., 24), readily assembled in one step from the quinols (e.g., 27) by a simplified version of the Dowd oxidation, are shown to undergo rearrangement to pyranonaphthoquinones (e.g., 28) and their ring contracted homologues (e.g., 29) on flash vacuum pyrolysis at 450 °C and 0.01 Torr. The rearrangement has been demonstrated to be useful for a regiospecific synthesis of lambertellin (3). Similarly, the masked aziridinocyclopentanone 9 rearranges to 2-pyridone (37).