Further Novel 6,7-Dimethoxy-8-Prenylated Coumarins from the Aerial Parts of Phebalium elatius ssp. becklevi

Abstract

From the aerial parts of Phebalium elatius ssp. beckleri six novel coumarins have been isolat­ ed. These com pounds are all based on a 6,7-dimethoxycoumarin nucleus with a modified C-8 isoprenyl substituent. The prenyl side chains were identified, primarily on the basis of NMR studies, as 1,2-epoxy-3-methylbut-3-enyl = (+)-6 -methoxyphebalosin (1), 1-acetoxymethyl-2-methylprop-2-enyl = (+)-6 -m ethoxyisomurralonginol acetate (2), 1,2-epoxy-3-hydroxy-4-(3-m ethylbutanoyloxy)-3-m ethylbutanyl = 1 ′,2′-epoxy-6-methoxycasegravol-4′-(3-methyl)-butanoate (3), 1-(S)-hydroxy-3-methyl-2-oxobutanyl = (+)-6 -methoxymurranganon (4), 3-methyl-2-oxotetrahydrofuran-4-yl = 6-methoxy-3′.4′-dihydroisomicrominutin (5) and (E)-3-hydroxy-3-methylbut-l-enyl = 6 -methoxymurraol (6).