Josephine M. Peach

Two alexines [3-hydroxymethyl-1,2,7-trihydroxypyrrolizidines] from Castanospermum australe

Abstract Two new alexines have been isolated from Castanospermum australe . The structure of 1,7a-diepialexine was firmly established by X-ray crystallographic analysis of the corresponding 1,7-isopropylidene derivative. The structure of the second new alexine was tentatively assigned as 7,7a-diepialexine or its enantiomer. The abilities of naturally occurring alexines to inhibit mouse gut disaccharidase and fungal glucan 1,4-α-glucosidase are compared.

Isolation from atelia herbert-smithii pittier (sophoreae, leguminosae) and x-ray structure of cis-1-amino-3-hydroxymethyl-cyclobutane-1-carboxylic acid, an achiral non-protein amino acid

Abstract barcis -1-Amino-3-hydroxymethyl-cyclobutane-1-carboxylic Acid (1) has been isolated from Atelia herbert-smithii Pittier (Leguminosae) and its structure determined by spectroscopic and X-ray crystallographic methods. By a study of the 1H NMR spectrum of the crude extract, the relative amount of (I) to that of methanoproline in the plant was shown to be 1 to 1.15.

Retention and apparent inversion during azide displacement of α-triflates of 15-lactones

Abstract Reactions of azide ion with 2-O-trifluoromethanesulphonates of both 34:67-di-O-isopropylidene-D- glycero -D- talo -hepton-0-15-lactone and of 34;67-di-O-isopropylidene-D- glycero -D- galacto -heptono-1-5-lactone give predominantly 2-azido-2-deoxy-3 4:6 7-di-O-isopropylidene-D- glycero -D- galacto 5-lactone initially which then isomerises under the reaction conditions to 2-azido-2-deoxy-34:67-di-O-isopropylidene-D glycerol -D- talo -heptono-1 X-ray crystal structure analyses of 34;67-di-O-isopropylidene-D- glyceroD -1- talo -heptono-1 5-lactone. and 2-azido-2-deoxy-3 4:6 7-di-O-isopropylidene-D- glycero -D- talo -heptono-15-lactone are reported.

Synthesis of the potent antiviral oxetane nucleoside epinoroxetanocin from D-lyxonolactone

Abstract A short synthesis of epinoroxetanocin [9-(β-D-threo-oxetanosyl)adenine], free from its α-anomer, from D-lyxonolactone is described. The X-ray crystal structure of a benzylidene-protected derivative of epinoroxetanocin is reported. A comparison of the in vitro activity against HIV-1 of oxetanocin, noroxetanocin and epinoroxetanocin as anti-viral agents is given.

Copper and zinc bis(thiosemicarbazonato) complexes with a fluorescent tag: synthesis, radiolabelling with copper-64, cell uptake and fluorescence studies

The synthesis of new copper(II) bis(thiosemicarbazonato) complexes with an appended pyrene chromophore and their zinc(II) analogues is reported. The new proligands and their copper(II) and zinc(II) complexes were characterised by a combination of NMR, EPR, high performance liquid chromatography, mass spectrometry, electronic spectroscopy and electrochemical measurements. The new copper(II) complexes are fluorescent as a consequence of an appended pyrene substituent that is separated from the sulphur coordinating to the metal ion by five bonds. The emission from the pyrene substituent is concentration- and solvent-dependent with characteristic formation of excimer aggregates. A radioactive 64Cu complex has been prepared. Cell permeability, intracellular distribution and importantly the ability to cross the nuclear membrane to target DNA were investigated using confocal fluorescence microscopy in a human cancer cell line under normal oxygen conditions and hypoxic conditions. In both cases, there was no evidence of uptake of the copper(II) bis(thiosemicarbazonato) complexes in the area of the cell nucleus.

Oxetane nucleosides with fluorine and azide substitutents: nucleophilic displacements on an oxetane ring

Abstract Fluorine and azide substituents are introduced into an oxetane ring by nucleophilic displacement reactions; the syntheses and anti-viral activities of 9-(2′-azido-2′-deoxy-β-D- erythro -oxetanosyl)-adenine and of 9-(2′-deoxy-2′-fluoro-β-D- erythro -oxetanosyl)-adenine are reported.

Acetonides of heptonolactones: Powerful chirons

Abstract Heptonolactones, in which all the functional groups except one can be protected with a single ketal protecting group, have great potential as starting materials within the chiral pool. The practical synthesis and characterisation of acetonides of glycero-talo- and glycero-galacto -heptono-lactone are described. X-ray crystal structures of D - glycero - D - talo -heptono-1,4-lactone and 2,3:5,6-di-O-isopropylidene- D - glycero - D - talo -heptono-1,4-lactone are reported.

Synthesis of 2R,3S,4R-dihydroxyproline from D-ribonolactone

Abstract A synthesis of 2R,3S,4R-dihydroxyproline is described in which an azide is introduced into C-2 positon of D-ribonolactone with retention of configuration.

Chiral oxetanes from sugar lactones: Synthesis of derivatives of 3,5-anhydro-1,2-O-isopropyl-α-D-glucuronic acid and of 3,5-anhydro-1,2-O-isopropyllidene-β-L-iduronic acid

Abstract Ring contraction reactions of triflates of α-hydroxy-γ-lactones provide an approach to the synthesis of chiral polyfunctionalised oxetanes from sugars. Treatment of 1,2-0-isopropylidene-5-0-trifluoromethanesulphonyl-α-D-glucuronolactone with benzylamine or with potassium carbonate in methanol gave ring contraction reactions to form oxetanes in good yield.

Photolabile benzoin and furoin esters of a biologically active peptide

Abstract Benzoin and furoin esters of N-carbobenzyloxyglycylphenylalanine were prepared and photolyzed under a variety of conditions. The photochemistry of peptide-derived benzoin esters is more efficient than that of furoin esters and is appropriate for the photolytic initiation of biochemical processes. Methodology to assess the enantiomeric purity of the resulting free peptide was developed and used to monitor the protection-deprotection chemistry. Synthesis based on alkylation of the cesium salt of the peptide proved more effective than DCCI-mediated chemistry on stereochemical grounds.