Natasha L. Hungerford

An octameric carbopeptoid; secondary structure in octameric and tetrameric 5-aminomethyl-tetrahydrofuran-2-carboxylates

Abstract The efficient synthesis of an octameric furanose carbopeptoid, readily purified by chromatography in ethyl acetate:hexane (2:1), is reported. Extensive NMR studies suggest that two tetrameric 5-aminomethyltetrahydrofuran-2-carboxylates are prone to adopt solution conformations reminiscent of a repeating β-turn, a third tetramer and the corresponding octamer may tend towards a left-handed α-helix.

From sequencamers to foldamers? Tetrameric furanose carbopeptoids from cis- and trans-5-aminomethyl-tetrahydrofuran-2-carboxylates

Abstract The synthesis of three stereoisomeric cis - and trans -5-azidomethyl-tetrahydrofuran-2-carboxylates in which a ketal-protected cis -diol unit is present is described. The monomers undergo efficient oligomerisation to tetrameric carbopeptoids in which the diol protection facilitates ready purification by chromatography which augurs well for the formation of homogeneous higher polymers.

Cis- and trans-3-Azido-oxetane-2-carboxylate scaffolds: Hexamers of oxetane cis-β-amino acids

Efficient synthesis of both cis- and trans-3-azido-oxetane-2-carboxylates relies upon efficient nucleophilic displacements of 3-O-triflates of oxetanes by trifluoroacetate and azide. Such structures are scaffolds for incorporation of oxetane-β-amino acids into oligomers; the synthesis of a series of protected β-hexapeptides and the X-ray crystal structure of methyl 2,4-anhydro-6-deoxy-5-O-benzyl-l-altronate are reported.

Tetrahydrofuran amino acids: Secondary structure in tetrameric and octameric carbopeptoids derived from a D-allo 5-(aminomethyl)tetrahydrofuran-2-carboxylic acid

The synthesis of a D-allo-5-(azidomethyl)tetrahydrofuran-2-carboxylate as an amino acid precursor (in which the carboxylic acid is cis to the azidomethyl substituent and trans to the diol moiety) is reported from D-ribose. The oligomerisation of this monomer to dimeric, tetrameric and octameric carbopeptoids is described. NMR studies into the solution structures of cyclohexylidene-protected oligomers and of a deprotected tetramer with eight free hydroxy groups are described.

Isolation and Structure of Some Constituents of the Australian Medicinal Plant Tinospora smilacina ('Snakevine')

The structures of a number of compounds isolated from the stems of Tinospora smilacina (known as ‘snakevine’) have been determined. The known clerodane-type compound columbin is a major component, and two new minor compounds incorporate a heavily oxygenated tetrahydrofuran ring in place of the furan ring of columbin. The lignan isolariciresinol is also shown to be a minor component, along with dihydrosyringenin. The traditional medicinal use of the vine, particularly in countering snake venom, may be associated primarily with the presence of columbin.

Synthesis and Evaluation of Anticancer Natural Product Analogues Based on Angelmarin: Targeting the Tolerance towards Nutrient Deprivation

Inspired by nature: Angelmarin is an anticancer natural product with potent antiausterity activity, that is, selective cytotoxicity towards nutrient-deprived, resistant cancer cells. Through structure-activity relationship studies, three analogues were identified as lead compounds for the develpoment of molecular probes for the investigation of the mode of action and biological targets of the antiausterity compounds.

Tetrahydrofuran amino acids: β- and γ-azidotetrahydrofurancarboxylic acid monomers derived from D-glucoheptonolactone as building blocks for β- and γ-oligopeptides

The synthesis of both a β (L-allono) and a γ (D-allono) tetrahydrofuran azido acid from a single heptono sugar lactone as monomers for peptidomimetic oligomers is described.

Biogenesis of sex pheromones in the female olive fruit-fly

A likely pathway to the sex pheromones of Bactrocera oleae (olive fruit-fly) is presented, based mainly on feeding experiments with deuterium labelled precursors.

Titanium(II)-based Z-reduction of alkynes: stereo- and regio-specific Z-dideuteriation of conjugated and methylene-skipped ynes

A TiII-mediated, stereo- and regio-specific reduction of isolated, conjugated and methylene skipped poly-ynes to the corresponding Z-dideuterio polyenes in a one-pot procedure with D2O as deuterium source is described, and this methodology (using H2O) is applied to the synthesis of (3E,8Z,11Z)-tetradeca-3,8,11-trienyl acetate, the major sex attractant of Scrobipalpuloides absoluta, a destructive pest of tomatoes.

(4+3) Cycloaddition Reactions of N-Alkyl Oxidopyridinium Ions

N-Methylation of methyl 5-hydroxynicotinate followed by reaction with a diene in the presence of triethylamine afforded (4+3) cycloadducts in good to excellent yields. High regioselectivity was observed with 1-substituted and 1,2-disubstituted butadienes. Density functional theory calculations indicate that the cycloaddition involves concerted addition of the diene onto the oxidopyridinium ion. The process provides rapid access to bicyclic nitrogenous structures resembling natural alkaloids.