Allick R. Lal

Ent-atisane diterpenes from Euphorbia fidjiana

Abstract The heartwood of the Fijian species Euphorbia fidjiana has yielded seven new ent-14-oxo-atisenes, four ent- atisane-16,17-diols, a 4,5-seco-atisene, and a 3,4-seco- atisene-ent-13[S]-hydroxy-14-oxo-3,4-seco-atis-16-en- 3,4-olide, as well as two chlorinated ent-atisanes which were identified as artifacts. Their structures and relative stereochemistry have been determined by detailed high field NMR studies and from an X-ray structure analysis of ent-13-[S]- hydroxyatis-16-ene-3,14-dione. Their absolute configuration is inferred from an X-ray structure of ent-17-p- bromobenzoyloxy-16α-hydroxyatisan-3-one.

Ent-14[S],16β,17-trihydroxyatisan-3-one and further constituents from Euphorbia fidjiana

Abstract The heartwood of the Fijian species Euphorbia fidjiana has yielded the new compounds ent -14[ S ],16β,17-trihydroxyatisan-3-one, 5-hydroxyethylmellein, and 6-hydroxy-5-methylmellein, and 24 other compounds identified as stigmasterol, β-sitosterol, stigmasterone, β-sitosterone, 3-hydroxystigmastan-6-one, butyrospermol, 24-methylenecycloartan-3β-ol, cycloart-24-en-3β-ol, 3β-hydroxycycloart-25-en-24-one, 24-methylenecycloartan-3-one, cycloart-24-en-3-one, lasiodiplodin, des- O -methyllasiodiplodin, 5-methylmellein, 5-methoxymellein, 5-hydroxy-methylmellein, scopoletin, xanthoxylin, 2,4,6-trimethoxyacetophenone, erythritol, d -mannitol, d -arabitol, β- d -glucose, and α- d -glucose. Lasiodiplodin, des- O -methyllasiodiplodin and the three substituted melleins may be products of fungal infestation of the wood.

Ent-pimarane and ent-abietane diterpenes from Euphorbia fidjiana

Abstract The heartwood of the Fijian species Euphorbia fidjiana has yielded three new ent -pimaren-3-ones, a new ent -abietadienolide, as well as the known compounds jolkinolides A and E. The structures and relative stereochemistry of the ent -pimaren-3-ones have been determined from high field NMR studies. The structures of the γ-lactones were assigned on the basis of NMR data and an X-ray structure analysis. The structures of the previously reported pseudojolkinolides have been revised.

Sesterterpene lactones from a sponge species of the genus Dactylospongia

Abstract A new species of sponge in the genus Dactylospongia has yielded two new isomeric sesterterpene lactones [ 1 ] and [ 2 ]. The structures and relative stereochemistry were determined from 1-D and 2-D nmr studies and an X-ray structure of [ 2 ]. These hexacyclic compounds are probably identical with cyclisation products [ 4 ] and [ 5 ] of luffolide [ 3 ] which has been isolated from a Luffariella sponge.

New oxidised ent-atisene diterpenes from Euphorbia fidjiana

Abstract The heartwood of Euphorbia fidjiana Boiss. has yielded three oxygenated ent -atisene diterpenoids, ent -13[R]-hydroxy-3,14-dioxo-16-atisene [ 1 ], ent -3,14-dioxo-16-atisene [ 2 ] and ent -13[R],14[R]-dihydroxy-3-oxo-15-atisen-17-al [ 3 ]. The structure and relative stereochemistry were determined from detailed nmr studies and an X-ray structure of [ 1 ]. [ 1 ] is converted in air into [ 3 ].

Sesquiterpenes from Heritiera ornithocephala

Abstract Two new sesquiterpenes and 7-hydroxycalamenene, each of which contain a cadina-1,3,5-triene skeleton, together with a new benzopyran derivative have been isolated from the heartwood of the Fijian species Heritiera ornithocephala . The structure and relative stereochemistry of the new compounds have been determined from high field NMR studies.