Prenylcoumarins from Murraya paniculata var. omphalocarpa(Rutaceae): The Absolute Configuration of Sibiricin, Mexoticin and Omphamurin.

Three new prenylcoumarins, murpaniculol senecioate, 5-methoxymurrayatin and omphamurin isovalerate were isolated from the leaves of Murraya paniculata var. omphalocarpa (Rutaceae), together with six known coumarins, paniculatin, (-)-sibiricin, 5, 7-dimethyoxy-8-(3'-methyl-2'-oxobutyl)coumarin, (-)-mexoticin, omphamurin and omphalocarpin. Their structures were characterizied on the basis of spectroscopic evidence. The absolute configulation of omphamurin at the C-2' position has been determined to be S by Horeau's method. THe absolute stereochemistry of (-)-mexoticin and (-)-sibiricin has also been established by their chemical correlation with omphamurin.