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Two new cembranoid lactones have been isolated from Barrier Reef collections of Sinularia flexibilis. Other metabolites include four previously reported macrocyclic diterprenes. The structure and relative configuration of flexibilide (4), C20H30O4, was determined by single- crystal X-ray diffraction methods. The colourless crystals are orthorhombic, space group P212121, a 10.682, b 30.404, c 5.779 Ǻ, Z 4.

A furanoquinol, C22H28O3, extracted from a sinularian soft coral has been shown to have the structure (3) based on spectroscopic evidence and the preparation of the related furanoquinone (4).Tables of 1H and 13C N.M.R. values for compounds (3) and (4) are given in two solvents. The compound (3) is best regarded as a modified polyprenylated quinol, and has the systematic name: 2-[3?,7?-dimethyl-8?-(4?-methyl-2?-furyl)octa- 2?,6?-dienyl]-5-methylhydroquinone.

The structure and absolute configuration of heterocladol, C15H26BrClO (6), have been determined by single-crystal X-ray diffraction methods. This compound is the first example of a selinane skeleton reported from Laurencia species and its structure can be rationalized in terms of a trans-annular ring closure of a germacradiene. The colourless crystals are monoclinic, space group P21, with a 11.852, b 14.486, c 10.932 Ǻ, β 119.6, Z4.

The lipid-soluble extract of the brown alga Cystophora torulosa has yielded a complex mixture of polyketide-derived alkenyl resorcinols and a phloroglucinol, together with two straight chain polyenes. Two polyprenyl chromans were also isolated in low yield.

Treatment of 1-aci-nitro-1,2,2-triphenylpropane (1) with hydrochloric acid leads to the formation of 3,5,5-triphenylisoxazoline (3), not 3,4,4-triphenylisoxazoline (2) as previously reported. The route from (1) to (3) has been shown to involve a fragmentation of the aci-nitro compound, similar to the ?abnormal? Beckmann rearrangement of oximes, to give 1,1-diphenylethylene and benzonitrile oxide, which then combine in a 1,3-dipolar addition.

Lipases from porcine pancreas and from Pseudomonas cepacia catalyze the ring-opening polymerization of lactones. Polymerization of the four-membered β-butyrolactone yielded poly(3-hydroxybutyrate) in up to 89% yield with a degree of polymerization of 3−12. Polymerization of the four-membered β-propiolactone, the five-membered γ-butyrolactone, and the seven-membered ε-caprolactone also yielded the corresponding polyesters in good yields with degrees of polymerization up to 25. Coordination catalysts, such as alumoxanes, fail in the homopolymerization of γ-butyrolactone; thus this lipase route is the first homopolymerization of γ-butyrolactone. To characterize the product polyesters, we used the method of MALDI-TOF mass spectroscopy to determine both the true molecular weight of the components and the mass of the repeat unit.

The (Z) and (E) pairs of 5-aminopent-2-enoic acid and 5-aminopent-3- enoic acid, as well as the related 5-aminopent-3-ynoic acid, have been prepared for structure-activity studies on GABA receptors. Only the (Z) isomers were active as GABA agonists with (Z)-5-aminopent-2-enoic acid being two- to four-fold more active than 5-aminopentanoic acid.

(Z)-4-Aminocrotonic acid can be conveniently prepared via crystalline phthalimido protected intermediates.

5-(Aminomethyl)-3-hydroxyfuran-2(5H)-one (4) has been synthesized as a GABA analogue in five steps from hex-3-enedioic acid, the enolic α-keto group being introduced under mild conditions by means of a singlet oxygen cleavage of an enamino lactone. The compound showed negligible activity as a GABA agonist with respect to inhibition of [3H]GABA binding, uptake and trans amination in rat brain membranes

The structure of a diterpene with a new bicarbocyclic ring skeleton has been solved by analysis of the 400-MHz 1H n.m.r. spectrum, and confirmed by a single-crystal X-ray analysis.

4-Amino-5-bromopyrrolo[2,3-d]pyrimidine has been isolated from a sponge (Echinodictyum sp.). The pharmacologically active constituent of the red alga Hypnea valendiae has been identified as 4-amino-7-(5'-deoxyribos-1'β-yl)-5-iodopyrrolo[2,3-d]pyrimidine (7). A second nucleoside, tentatively assigned as the 1'α isomer of (7), has also been isolated.

The dichloromethane-soluble extract of the brown alga Acrocarpia paniculata has yielded two homologous branched chain lipids containing a furan ring. Reaction of a substituted furan with 4-phenyl-4H-1,2,4-triazoline-3,5-dione to yield an alkyl 2-ene-1,4-dione was used to determine the orientation of substituents on a 2,3,5-substituted furan.

Four new acetate-derived metabolites have been isolated from two collections of the red alga Phacelocarpus labillardieri. Three of these metabolites were 2,6-disubstituted pyran-4-ones containing a macrocyclic enol-ether ring. The fourth compound was a 6-substituted pyran-2-one derivative.

Eight new sesquiterpenes, (ll), (12), (14)-(16), (18), (20) and (21), have been isolated from four separate small collections of the sponge Dysidea herbacea. The structures of these compounds, all of which contain a furan group, were derived by comparison of their spectral properties with those of known sesquiterpenes.

Two new cembranolides, (1R,2S,3E,7R,8R,11E,14S)-7,8-epoxy-14-hydroxycembra-3,11,15-trien-17,2-olide and (lR,2R,3E,7R,SR,11E,14R)-7,8-epoxy-14-hydroxycembra-3,11,15-trien-17,2-olide, have been isolated from separate species of Cespitularia (soft coral).

The structures of two new N-methylated spermidine amides, (4) and (5), isolated from a soft coral (Sinularia sp.) are described together with the synthesis of one of them. Two new 9,11-secocholestane derivatives, (6) and (7), have also been isolated from the same organism.

Two new cembrane diterpenes, related to sarcophine, have been isolated from a soft coral (Sarcophyton sp.). Structures were solved primarily by spectral methods. The pharmacological profile of one metabolite (5) is briefly discussed.

Five new scalarane sesterterpenes have been isolated from a Western Australian sponge (Lendenfeldia sp.). As with earlier reported examples of these compounds, several of these metabolites of this sponge are extremely potent inhibitors of platelet aggregation.

Great Barrier Reef sponges of the genus Spongia have yielded eight closely related tetracyclic furanoditerpenes. The structures, assigned on the basis of spectral methods, have been confirmed by a single-crystal X-ray analysis of one of the metabolites and the relative stereochemical features have been defined. The absolute configuration of this metabolite was determined by circular dichroism, which allowed the relationship between the eight new compounds to be determined.

The isolation of an epoxyisoneocembrene-A [(E,E,E)-11,12-epoxy-1- isopropyl-4,8,12-trimethylcyclotetradeca-1,3,7-triene] (1), from the soft coral Sinularia grayi, is reported and its structure demonstrated by chemical and spectroscopic means. The isolation of an isomer of the reported cembrene sarcophytoxide (2) and of isoneocembrene-A (3), an isomer of the termite trail pheromone neocembrene-A, from the soft coral Sarcophyton ehrenbergi is also reported. Chemical transformations enabled (1) to be converted into (3).

Five new quinones have been isolated from a sponge tentatively classified as Stelospongia conulata. Isospongiaquinone (7) has a rearranged drimane skeleton whereas spongiaquinone (19), cyclo- spongiaquinone-1 (20), cyclospongiaquinone-2 (21) and dehydrocyclospongiaquinone-1 (22) have a normal drimane skeleton. The structures of these were derived from chemical and spectral evidence.

Three new compounds containing the laurene skeleton are reported from the red alga Laurencia filiformis f. heteroclada.

Extraction of the soft coral Sinularia facile afforded two cembranoid diterpenes whose structures and absolute configurations have been determined as (1R,4R,2E,7E,11E)-cembra-2,7,11-trien-4-ol (1) and (1R,3S,4S,7E,11E)-3,4-epoxycembra-7,11,15-triene (2).

Seven novel metabolites, each originating from four bromotyrosine units, have been isolated from the sponge Ianthella basta. Bastadin-1 (2), bastadin-2(3) and bastadin-3(4) are derived from a single phenol oxidative coupling whilst the macrocyclic compounds bastadin-4(5), bastadin-5(6), bastadin-6(8) and bastadin-7(7) are formed by two phenol oxidative coupling reactions. Compounds (2)-(8) showed potent in vitro antimicrobial activity against Gram-positive organisms.

The dichloromethane-soluble secondary metabolites of four Cystophora species, C. monilifera, C. congesta, C. expansa and C. scalaris, are described. The structures of two new acyl phloroglucinols isolated from C. monilifera have been established by a combination of spectral and chemical methods.

The antiinflammatory principle of the brown alga Caulocystis cephalornithos has been shown to be 6-tridecylsalicylic acid. Four other metabolites, 3-tridecylphenol, pentadec-1-ene, (E)-heptadec-3-en- 2-one and 8-hydroxy-3-undecyl-1H-2-benzopyran-1-one were also isolated from the dichloromethane extract of the freeze-dried alga.

The structures of six new C26 tetracyclic terpenoids isolated from two Phyllospongia spp. are described. The relative stereochemistry of one compound was solved by a single-crystal X-ray determination.

Three amides derived from tyramine, 4-(2-aminoethyl)-2-methoxyphenol and 5-(2-aminoethyl)-2-methoxyphenol and a novel lipid acid, (Z)-3- methyldodec-2-enoic acid, were isolated from the soft coral Sinularia flexibilis. The structures, obtained by spectral methods, were confirmed by synthesis.