Dedicated to Professor Albert Eschenmoser on the occasion of his 80th birthday 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 ( ), (2R)-d-cadin-4-ene-2,10-diol (3), (2R)-dcadina-4,9-dien-2-ol (4), (1R,2R)-dihydroxyisodauc-4-en-14-ol ( ) and its acetonide 6 (artifact), as well as the two triterpenoids (3b,16b)-16-hydroxylup-20(29)-en-3-yl (E)-3-(4-hydroxyphenyl)prop-2-enoate ( ) and (3b,16b)-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. ). A plausible biosynthesis of the sesquiterpenoids 1 -5 is proposed (Scheme), starting from (À)-germacrene D as the common biogenetic precursor.
Results and
Discussion. -Compound 1 was obtained as an optically active, yellow oil, with [a] 25 D = + 23.5. The molecular formula was deduced as C 19 H 28 O 4 by HR-FAB-MS (m/z 321.2074 ([M + H] + ; calc. 321.2066)). The 13 C-NMR (DEPT) spectrum (Table ) showed 19 signals, including seven sp 3 CH, one sp 2 CH 2 , two sp 3 CH 2 , and five Me groups, together with three sp 2 and one sp 3 quaternary C-atom(s). The IR absorptions at 1746 and 1245 cm À1 indicated the presence of an AcO group, the absorptions at 1650 and 1040 cm À1 suggested an exo-methylidene group, and those at 3076, 3017, and 1650 cm À1 were attributed to a cyclopropyl unit. The 1 H-NMR spectrum of 1 (Table ) displayed signals for two CH (vicinal to an AcO group) at d(H) 5.38 (d, J = 10.5 Hz) and 4.84 (ddd, J = 10.5, 10.5, 5.5 Hz), which were attributed to H b ÀC(1) and H a À C(2), respectively. In turn, H b ÀC(1) and H a ÀC(2) showed long-range couplings to the C=O groups at d(C) 171.1 and 170.3, respectively. These correlated with Me groups at d(H) 2.06 and 2.01, establishing the presence of two AcO groups.
Further, H a ÀC(2) of 1 was 1 H, 1 H-correlated with H a ÀC(3) at d(H) 2.63 (ddd, J = 13.0, 5.5, 1.5 Hz) and with H b ÀC(3) at d(H) 2.46 (ddt, J = 13.0, 11.0, 1.5 Hz), which exhibited a cross-peak to the sp 2 -hybridized C(15) at d(C) 114.4. Thus, the CH 2 (15) H-atoms at d(H) 4.89 (t,