Uncommon Sesquiterpenoids and New Triterpenoids from Jatropha neopauciflora (Euphorbiaceae)

Eight new terpenoids ( 1 – 8 ) were isolated from the bark of Jatropha neopauciflora , together with eight known compounds. The new isolates include the sesquiterpenoids (1 R ,2 R )‐diacetoxycycloax‐4(15)‐ene ( 1 ); (1 R ,2 R )‐dihydroxycycloax‐4(15)‐ene ( 2 ), (2 R )‐ δ ‐cadin‐4‐ene‐2,10‐diol ( 3 ), (2 R )‐ δ ‐cadina‐4,9‐dien‐2‐ol ( 4 ), (1 R ,2 R )‐dihydroxyisodauc‐4‐en‐14‐ol ( 5 ) and its acetonide 6 (artifact), as well as the two triterpenoids (3 β ,16 β )‐16‐hydroxylup‐20(29)‐en‐3‐yl ( E )‐3‐(4‐hydroxyphenyl)prop‐2‐enoate ( 7 ) and (3 β ,16 β )‐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.