Uncommon Sesquiterpenoids and New Triterpenoids fromJatropha neopauciflora (Euphorbiaceae)

Abstract

Eight new terpenoids (1–8) were isolated from the bark of Jatropha neopauciflora, together with eight known compounds. The new isolates include the sesquiterpenoids (1R,2R)-diacetoxycycloax-4(15)-ene (1); (1R,2R)-dihydroxycycloax-4(15)-ene (2), (2R)-δ-cadin-4-ene-2,10-diol (3), (2R)-δ-cadina-4,9-dien-2-ol (4), (1R,2R)-dihydroxyisodauc-4-en-14-ol (5) and its acetonide 6 (artifact), as well as the two triterpenoids (3β,16β)-16-hydroxylup-20(29)-en-3-yl (E)-3-(4-hydroxyphenyl)prop-2-enoate (7) and (3β,16β)-16-hydroxyolean-18-en-3-yl (E)-3-(4-hydroxyphenyl)prop-2-enoate (8). The structures of these compounds were established by extensive 1D- and 2D-NMR spectroscopic methods, and their absolute configurations were determined by circular-dichroism (CD) experiments, and by X-ray crystallographic analysis (compound 7; Fig. 3). A plausible biosynthesis of the sesquiterpenoids 1–5 is proposed (Scheme), starting from (−)-germacrene D as the common biogenetic precursor.