Acid-catalyzed rearrangement of an epoxy coumarin phebalosin. The revised structure of murralongin.

Abstract

On treatment with acid, the well-known epoxy coumarin phebalosin (I) undergoes rearrangement to afford murralogin, a naturally occurring coumarin bearing an unusual isoprenoid unit. The structure of murralogin is reviewed, based on the hypothetical mechanism of rearrangement, and finally revised to (V) by X-ray crystalography.