The chemistry of the Euphorbiaceae. VII. The diterpenes of <i>Ricinocarpus stylosus</i> Diels

Abstract

The ether extract of Ricinocarpus stylosus has yielded polyalthic acid, three new naturally occurring flavonoid pigments and four new kauranoid diterpenes. The latter have been shown to be 16a-(-)-kauran-l7,19-dioic acid (I; R,R' = CO2H), 19-hydroxy-16a-(-)-kauran-17-oic acid (I; R = CH2OH, R' = CO2H), kauran-16a,-17,19-triol (III; R,R' = CH2OH) and (-)-kaur-16-en-19-oic acid (IV; R = CO2H). The N.M.R. correlations of these diterpenoids are discussed.