Four new oxygenated lupanes isolated from the stem bark of Pleurostylia opposita (Wall) Alston (Celastraceae) have been shown to be lupa-5,20(29)-dien-3-one (2), 6P,20-dihydroxylupan-3-one (5), 3P,6P-dihydroxylup-20(29)ene (6). and GP,28-dihydroxylup-20(29)-en-3-one (8). The structures of these compounds were established on the basis of spectroscopic ( l H n.m.r. and mass spectral) and chemical evidence. Deshielding of three methyl signals in the 'H n.m.r. spectra of 6P-hydroxylupane derivatives has been attributed to 1,3-diaxial interaction between the relevant methyl group and the 6P-hydroxy-group.Pmufiusz-YuA OPPOSITA (Wall) Alston (Celastraceae) is a moderately sized tree found in the dry zone of Sri Lanka. Previous work on the genus PZezcrostyZia has led to the isolation of friedelin , epi-friedelinol, and the spermidine celacinnine from the leaves of P. a f ~i c a n a . ~ Pristimerin, a-amyrin, p-sitosterol, and eight other triterpenes were isolated from the benzene extract of the stem bark of P. opposita. Several lupane derivatives have been isolated from the Cela~traceae.~-' Six of the triterpenes isolated from P. op#osita were found to be lupane derivatives which have not been reported previously in this family. In this paper we report the isolation and structure elucidation of four new oxygenated lupane derivatives.
RESULTS AND DISCUSSIONPlant material used in this investigation was collected from Murugandy, in the Jaffna district of the Northern province of Sri Lanka. The benzene extract of the dried, powdered stem bark of a well matured tree of P. opposita yielded pristimerin, a-amyrin, p-sitosterol, and eight compounds (1)-( 8), all of which gave a positive Liebermann-Burchard reaction. Compounds (2), (4), (5), ( 6), (7), and (8) have been identified as lupa-5,20(29)-dien-3-one (2), 20-hydroxylupan-3-onc (4) ,8 6p,20-dihydroxylupan-3-one (5), 3p,Gp-dihydroxylup-20(29)-ene (6), 3pJ20-dihydroxylupane (7) and 6p,28dihydroxylup-20(29)-en-3-one (8), respectively. Compounds (2), (5), (6), and ( 8) are new lupane derivatives. Rigidenol, a lupane derivative with an or-hydroxy-substitutent at C-6 has been reported from Maytenus rigida (Celastraceae) .g Our results indicate this assignment to be doubtful. Hence, ( 5), (6), and (8) are the first examples reported of lupanes with an oxygen substituent at C-6. Di-and tri-oxygenated friedelin derivatives with a 6P-hydroxy-substituent have been reported from Kokoona xeyZanica belonging to the same family.10 l H N.m.r. and mass spectral evidence suggested the presence of a lupane skeleton in (2) and ( 4)-( 8). Two l -H doublets in the 6 4 . 6 4 . 5 region, and a 3-H doublet at 6 1.6-1.7 in the l H n.m.r. spectra of (Z), (6), and (8) indicated the presence of a lup-20(29)-ene system in these three compounds.ll Further, signals due to eight methyl groups, including two singlets at 6 1.1 and 1.2, in the n.m.r. spectra of (4), (5), and (7) showed the presence of a C(Me),OH group, and indicated that these compounds were 20-hydroxylupane derivatives8 Fragments at m / e 21...
