STEREOCHEMISTRY OF STRICTIC ACID AND RELATED FURANODITERPENES FROM CONYZA JAPONICA AND GRANGEA MADERASPATANA

Article abstract of DOI:10.1016/S0031-9422(00)80338-6

Extraction of Conyza japonica gave strictic acid, ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid and 5,7-dihydroxy-3,8,4'-trimethoxyflavone.Extraction of Grangea maderaspatana gave (-)-hardwickiic acid, ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid and 3-hydroxy-8-acetoxypentadeca-1,9,14-trien-4,6-diyne.The structure of ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid was deduced by spectroscopic methods and by partial synthesis from (-)-hardwickiic acid and the stereochemistries of strictic acid and ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid were established by correlation with ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid. - Keywords: Conyza japonica; Grangea maderaspatana; Compositae; Astereae; strictic acid; clerodanes; 5,7-dihydroxy-3,8,4'-trimethoxyflavone; 3-hydroxy-8-acetoxy-pentadeca-1,9,14-trien-4,6-diyne.