The structures of two halogenated diphenyl ethers from a marine sponge have been assigned from spectroscopic and X-ray crystallographic evidence. The two compounds have been identified as 3,5-dibromo-4-chloro-2-(2,4dibromophenoxy)phenol (1 ) and 3,5-dibromo-2-(2,4-dibrornophenoxy)phenol (2).AS part of a programme to investigate the natural products of marine organisms occurring off the Western Australian coast we have examined the constituents.of an unidentified sponge collected near Rottnest 1sland.t The two major constituents have been shown to be the new halogenated biphenyl ethers (1) and ( 2) and their structure has been secured by X-ray crystallographic analysis.Extraction of a diced sample of the sponge with organic solvents yielded a semi-crystalline extract which contained two major components, separable by column chromatography on alumina. The more polar component (1) (1.3% of the dry weight of the sponge), m.p. 181-181.5 "C, C,2H,Br,C102, showed signals in the n.m.r.
Br Br(1) R = CI (21 R = H spectrum attributable and penta-substituted able phenolic proton.to protons on isolated 1,2,4-triaromatic rings and an exchange-The phenolic hydroxy-group was located on the pentasubstguted ring since a shift to higher field of 0.51 p.p.m. was observed for the single aromatic proton in the n.m.r. spectrum of the sodium salt of (1) and this also suggests that the ring proton is ortho or para to the hydroxy-group. This information indicates that the second oxygen is involved in an ether linkage and the presence of a 2-(2,4-dibromophenoxy)phenol system was inferred from the mass spectrum which showed significant peaks at m/z 234, 236, and 238 ( C6H,Br2) probably arising from the rearrangement of the molecular ion as shown in the Scheme., Since the Br SCHEME position of the chlorine could not be readily assigned, an Museum (catalogue no. WAM 403-80).
The ether extract of Ricinocarpus stylosus
has yielded polyalthic acid, three new naturally occurring flavonoid pigments
and four new kauranoid diterpenes. The latter have been shown to be 16α-(-)-kauran-l7,19-dioic
acid (I; R,R' = CO2H), 19-hydroxy-16α-(-)-kauran-17-oic acid
(I; R = CH2OH, R' = CO2H), kauran-16α,-17,19-triol (III;
R,R' = CH2OH) and (-)-kaur-16-en-19-oic acid (IV; R = CO2H).
The N.M.R. correlations of these diterpenoids are discussed.
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