A hexane extract of the stem bark of Polyalthia longifolia furnished n
ine new clerodane and ent-halimane diterpenes, i.e. 16-hydroxycleroda-
4(18),13-dien-16,15-olide, 16-oxocleroda-4(18),13E-dien-15-oic acid, c
leroda-4(18),13-dien-16,15-olide, 16-hydroxy-ent-halima-5(10),13-dien-
16, 5-olide, 16-oxo-ent-halima-5(10),13E-dien-15-oic acid, ent-halima-
1(10),13E-dien-16,15-olide, 16-oxo-ent-halima-5(10),13E-dien-15-oic ac
id, ent-halima-5(10),13-dien-16,15-olide and ent-halima-5(10),13E-dien
-16,15-olide, along with five known clerodane diterpenes. The structur
es of these compounds were elucidated by spectroscopic methods. The 13
E configuration of two of the new ent-halimanes and one of the known c
lerodanes was firmly established by NOE experiments.