ent-Pimarane derivatives from Dysoxylum hainanense

Four ent-pimarene diterpenoids, ent-18-acetoxy-8(14)-pimarene-15S, 16-diol, ent-18-acetoxy-16-hydroxy-8(14) pimaren-15-one, ent-16,18-dihydroxy-8(14)- pimaren-15-one and ent-19-nor-4,16,18-trihydroxy-8(14)-pimaren- 15-one, tog ether with three known damarane triterpenoids, richenoic acid,eichlerianic acid and shoreic acid were isolated from the bark of Dysoxylum hainanense M err. Their structures were elucidated on the basis of spectroscopic techniq ues. The absolute configurations of four diterpenoids were assigned as ent- pimarene type by chemical transformation and by co-occurrence in the plant as well as by negative optical rotations for four compounds. (C) 2001 Elsev ier Science Ltd. All rights reserved.