Structures of four new oxygenated lupanes from Pleurostylia opposita(Celastraceae)

Abstract

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), 6β,20-dihydroxylupan-3-one (5),3β,6β-dihydroxylup-20(29)-ene (6), and 6β,28-dihydroxylup-20(29)-en-3-one (8). The structures of these compounds were established on the basis of spectroscopic (¹H n.m.r. and mass spectral) and chemical evidence. Deshielding of three methyl signals in the ¹H n.m.r. spectra of 6β-hydroxylupane derivatives has been attributed to 1,3-diaxial interaction between the relevant methyl group and the 6β-hydroxy-group.