258 results for Brimble, Margaret, Journal article

  • Professor Jim Coxon. A Tribute

    Brimble, Margaret; Steel, P (2006)

    Journal article
    The University of Auckland Library

    This special issue of the ARKIVOC is dedicated to Professor Jim Coxon to mark his 65 th birthday and acknowledge his contribution to New Zealand science through his diverse achievements in mechanistic organic chemistry carried out at the University of Canterbury.

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  • Equipment Access for Graduate Students - The First Hurdle

    Brimble, Margaret (2007)

    Journal article
    The University of Auckland Library

    Last month, Academy Councillor Carolyn Burns reflected on the unwieldy systems of compliance and accountability that our researchers face. These systems affect our opportunities to conduct cutting edge science in New Zealand, to attract excellent scientists from overseas, and to retain some of our best research scientists here. ...

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  • Instant Insight: Life at the Extremes

    Wilson, Zoe; Brimble, Margaret (2008)

    Journal article
    The University of Auckland Library

    There are minimature natural product libraries to be found in the most unexpected places. Zoe Wilson and Margaret Brimble of the University of Auckland, New Zealand, delve deeper.

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  • A Facile Synthesis of Spiroketals

    Brimble, Margaret; Officer, DL; Williams, GM (1988)

    Journal article
    The University of Auckland Library

    A convenient synthetic approach to spiroketals based on the addition of α-sulfonylcarbanions to lactones is described.

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  • Synthesis of a Functionalized Bis-Spiroacetal

    Brimble, Margaret; Williams, GM; Baker, R; James, M (1990)

    Journal article
    The University of Auckland Library

    The synthesis of bis-spiroacetal (15) bearing an hydroxymethyl group at C-2 is described establishing a methodology for preparation of the polyether antibiotics salinomycin and narasin. Formation of an important iodohydrin intermediate has been accomplished by a highly efficient reaction of an epoxide with LiI catalysed by BF3.Et2O in THF. Displacement of the resulting neopentyl iodide was achieved in high yield by reaction of the iodide with potassium superoxide in dimethylsulphoxide/tetrahydrofuran in the presence of 18-crown-6. The synthesis of bis-spiroacetal (15) has been achieved the following sequence.

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  • SYNTHESIS OF BICYCLIC PYRAZINONES VIA ADDITION OF HETEROCYCLIC AMINES TO A NITRO-ALKENE

    Brimble, Margaret; Johnson, AD (1994)

    Journal article
    The University of Auckland Library

    Michael addition of heterocyclic amines (6), (10), (13) and (17) to nitro-olefin (3) followed by reduction/cyclization of the nitro group of the adduct provides a convenient synthesis of the bicyclic pyrazinones (8), (12), (16), (19) and (20) which are found in several natural products. Michael addition of heterocyclic amines to a nitro-alkene followed by reduction/cyclization of the nitro group of the adduct provides a convenient synthesis of bicyclic pyrazinones found in several natural products.

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  • A Convergent Synthesis of the [4.4]-Spiroacetal-gamma-lactones Cephalosporolides E and F

    Brimble, Margaret; Finch, OC; Heapy, AM; Fraser, JD; Furkert, DP; O'Connor, PD (2011)

    Journal article
    The University of Auckland Library

    A short convergent synthesis of the fungal metabolites cephalosporolides E and F is reported. The key step makes use of a chelation-controlled Mukaiyam

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  • Synthesis of the Bis-Spiroacetal Moiety of 17-epi-20-Deoxysalinomycin

    Brimble, Margaret; Williams, GM (1992)

    Journal article
    The University of Auckland Library

    The synthesis of the bis-spiroacetal moiety of 17-epi-20-deoxysalinomycin (4) is reported in which the key step involves oxidative cyclization of the hydroxy spiroacetals 14 and 15 to the bis-spiroacetals 16 and 17 using (diacetoxyiodo)benzene and iodine under photolytic conditions.

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  • Synthesis of Tricyclic Aryl Spiroacetals Related to the Papulacandins

    Brimble, Margaret; Robertson, SG (1996)

    Journal article
    The University of Auckland Library

    A convenient synthesis of aryl spiroacetals related to the antifungal agents, the papulacandins, is reported. The synthetic methodology involves the addition of ortho-lithiated diethylbenzamides to lactones followed by acid catalysed cyclization of the resultant keto-alcohols. A series of aromatic spiroacetals is synthesized via the reaction of ortho-lithiated amides with lactones followed by cyclization of the resultant keto-alcohols with p-TSA.

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  • Toward the Total Chemical Synthesis of the Cancer Protein NY-ESO-1

    Brimble, Margaret; Harris, PWR (2010)

    Journal article
    The University of Auckland Library

    During the course of developing a synthetic route for the cancer protein NY-ESO-1 using native chemical ligation, a number of the required thioester polypeptide fragments were unable to be synthesized effectively using Boc solid phase peptide synthesis. Modification of the SPPS protocols to include an arginine tag at the C terminus linked via the thioester resulted in a better purity profile and enhanced solubility, facilitating purification by HPLC. During preparation of another reactive partner for ligation that contained an internal Cys(Acm) residue by Fmoc SPPS, extensive loss of the Acm group occurred during cleavage from the resin while substitution with Cys(tBu) resulted in no loss of protecting group. It was shown that native chemical ligation of N-terminal cysteine peptide 155–180 containing the Cys(tBu) residue with thioester 140–154 was slow, incomplete and led to extensive HPLC column fouling. Subsequent incorporation of a C-terminal arginine tag into the N-terminal NY-ESO-1 155-180 fragment joined by a base labile 4-hydroxymethylbenzoic acid (HMBA) linker facilitated rapid quantitative ligation. The HMBA linker was demonstrated to be stable to the conditions required for native chemical ligation, subsequent transformations and final purification. Importantly it was effectively removed at pH = 10.

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  • Addition of Silyloxydienes to 2-Substituted 1,4-Benzoquinones and 1,4-Naphthoquinones

    Brimble, Margaret; Elliott, RJE (1997)

    Journal article
    The University of Auckland Library

    Addition of 1-trimethylsilyloxybuta-1,3-diene 2 to the quinones 4,5,6,17,18,19,20 bearing formyl, acetyl, methoxycarbonyl or carboxamide substituents at C-2, afforded the Diels-Alder adducts 11,12,13,25,26,27,28 whereas addition of 2-trimethylsilyloxyfuran 3 afforded the fragmentation products 29,30,31,35,36,37,38. Quinones 7,21 bearing a carboxyl group at C-2 afforded 1,4-naphthoquinone and 9,10-anthracenedione with 2 and no adducts were isolated from reaction with 3. Benzoquinone-sulfide 8 afforded Diels-Alder adduct 14 and fragmentation product 32 with 2 and 3 respectively whereby reaction occurred on the less substituted double bond. No adducts were isolated upon treatment of naphthoquinone-sulfide 22 with either 2 or 3. The Diels-Alder adducts of benzoquinone-sulfoxide 9 and naphthoquinone-sulfoxide 23 with 2 underwent facile aromatisation to 1,4-naphthoquinone and 9,10-anthracenedione with 2. Addition of 3 to 9 afforded fragmentation product 33 whereas analogous reaction with 23 was unsucccessful. Addition of dienes 2,3 to benzoquinone-sulfone 10 afforded fragmentation products 16,34 respectively, whereas naphthoquinone-sulfone 24 afforded 9,10-anthracendione with 2 and no products with 3.

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  • REARRANGEMENT OF A FURO[3,2-B]NAPHTHO[2,1-D]FURAN TO A PYRANONAPHTHOQUINONE

    Brimble, Margaret; HODGES, R; STUART, SJ (1988-01-01)

    Journal article
    The University of Auckland Library

    The ceric ammonium nitrate oxidation of the furo(3,2-b]naphtho[2,l-d]furan-8(9H)- ones (5c,5d) gave the rearranged hemiketals (llc,lld) in 72-76% yield. -- Reduction of the hemiketals (llc,lld) provided an entry to a pyranonaphthoquinone with a fused Y-lactone as -- present in the pyranonaphthoquinone antibiotics kalafungin (5) and nanaomycin D (I).

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  • Preparation of truncated orf virus entry fusion complex proteins by chemical synthesis

    Yeung, Ho; Harris, Paul; Squire, Christopher; Baker, Edward; Brimble, Margaret (2014-06)

    Journal article
    The University of Auckland Library

    Members of the Chordopoxvirinae subfamily possess an unusual 11 protein entry-fusion complex (EFC) that is highly conserved and present in all species. The mode of action of this EFC is unknown, and the interactions of the constituent proteins are uncharacterised. Here, we present the chemical synthesis of membrane domain truncated linear constructs of two EFC proteins in orf virus, ORFV036 and 049. By using Boc solid phase peptide synthesis and native chemical ligation methods, these truncated proteins have been readily prepared in milligram quantities. These robust synthetic protocols allow ready access to these polypeptides to facilitate biological studies.

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  • Synthesis of an Isotopically-labelled Antarctic Fish Antifreeze Glycoprotein Probe

    Wojnar, Joanna; Evans, Clive; DeVries, AL; Brimble, Margaret (2011)

    Journal article
    The University of Auckland Library

    Antifreeze glycoproteins (AFGPs) are glycosylated polypeptides produced by Antarctic and Arctic fishes, which allow them to survive in seawater at sub-zero temperatures. An investigation into the postulated enteric uptake of AFGP synthesized in the exocrine pancreas of Antarctic fishes required a custom-prepared AFGP probe that incorporated seven isotopically-labelled Ala residues for detection by mass spectrometry. The AFGPs are composed of a repetitive three amino acid unit (Ala-Ala-Thr), in which the threonine residue is glycosylated with the disaccharide ??-d-Gal-(1???3)-??-d-GalNAc. The synthesis of isotopically-labelled AFGP8 (1), as well as the optimized synthesis of the protected glycosylated amino acid building block 2, is reported.

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  • The Influence of Microwave Irradiation on Lipase-Catalyzed Kinetic Resolution of Racemic Secondary Alcohols

    Bachu, P; Gibson, J; Sperry, Jonathan; Brimble, Margaret (2007)

    Journal article
    The University of Auckland Library

    The influence of microwave irradiation on the Novozyme 435?? (Candida antarctica lipase) catalyzed kinetic resolution of secondary alcohols with different functional groups was studied in comparison to the use of conventional heating at 60 ??C. p-Chlorophenyl acetate was used as an acyl donor and toluene as the solvent. (??)-1-Phenyl-1-propanol 1, (??)-1-(4-bromophenyl)-propan-1-ol 3, (??)-1-phenylbut-3-en-1-ol 5 and (??)-3-bromo-2-(2-hydroxypropyl)-1,4-dimethoxynaphthalene 7 were successfully resolved into their (S)-alcohols and (R)-esters, respectively, in good enantiomeric excess. Resolution of (??)-ethyl-5-(4-methoxybenyloxy)-3-hydroxypentanoate 9 afforded its (R)-alcohol and (S)-ester using this method. In addition, microwave-assisted lipase transesterification of meso-symmetric diol 11 effected desymmetrization to ester 12 with high enantiomeric excess. In all cases studied, the conversion value for the microwave-assisted lipase kinetic resolution of secondary alcohols was higher than that obtained using conventional heating.

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  • Synthesis of a novel polyaniline glycopolymer and its lectin binding studies

    Wilcox, Christopher; Jin, J; Charville, H; Swift, Simon; To, Teresa; Kilmartin, Paul; Evans, Clive; Cooney, Ralph; Brimble, Margaret (2013)

    Journal article
    The University of Auckland Library

    We report the multistep synthesis and polymerisation of a novel aniline derivative with a pendant ??-d-mannose substituent. The ??-D-mannose functionality was successfully introduced before polymerisation via copper-catalysed azide alkyne click chemistry and the resulting monomer was polymerised using general oxidative polymerisation conditions, producing a water soluble mannosylated polyaniline. The polymer was characterised by several techniques and compared with standard polyaniline. The selective binding of the polymer to Concanavalin A (ConA) was successfully demonstrated by the precipitation of polymer???ConA aggregates. Potential applications of these novel polyaniline glycopolymers could include the development of electroactive biomaterials with the ability to bind mannose receptors, or as sensors for proteins or microbes

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  • Approaches to a key lactone intermediate required for the synthesis of pyranonaphthoquinone antibiotics

    Brimble, Margaret; Spicer, Julie (1991)

    Journal article
    The University of Auckland Library

    Addition of 2-trimethylsilyloxyfuran (19) to naphthoquinone (20) gave in 91% yield the furo [3,2-b] naphtho [2,1-d]furan (18) which upon treatment with ceric ammonium nitrate gave the hydroxy ester (24) in 70% yield. Attempts to induce an intramolecular transesterification of hydroxy ester (24) to bislactone (6), a key intermediate required for the synthesis of several pyranonaphthoquinone antibiotics, were unsuccessful. Hydroxy ester (24), however, is closely related to the antibiotic juglomycin (32).

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  • Stereocontrolled Synthesis of a Key Lactone Intermediate Required for the Synthesis of Salinomycin

    Brimble, Margaret (1990-01-01)

    Journal article
    The University of Auckland Library

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  • Gold(I)-catalysed intramolecular hydroamination of ??-quaternary alkynes: synthetic studies towards spiroimine marine toxins

    Zhang, YC; Furkert, Daniel; Gu??ret, SM; Lombard, F; Brimble, Margaret (2011)

    Journal article
    The University of Auckland Library

    Cyclic spiroimines form an essential component of the bioactive pharmacophore in a number of potent fast-acting marine biotoxins, including the pinnatoxins, gymnodimine and the spirolides. These present a significant challenge for the total synthesis of this class of natural products. A novel approach to these cyclic spiroimines based on metal-catalysed hydroamination of spiroaminoalkyne precursors is reported herein. Au(PPh3)SbF6 was found to effect the formation of bench-stable 5,6- and 6,6-spiroimine systems in high yields, although the 7,6-analogue remained elusive. To the best of our knowledge these are the first reported examples of ??-quaternary cyclic imines formed via alkyne hydroamination.

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  • Addition of 2-tert-Butyldimethylsilyloxythiophene to Activated Quinones: An Approach to Thia Analogues of Kalafungin

    Brimble, Margaret; Laita, Olivia; Robinson, James (2006)

    Journal article
    The University of Auckland Library

    The uncatalyzed reaction of 2-tert-butyldimethylsilyloxythiophene 2 with 1,4-quinones bearing either an electron withdrawing acetyl or a carbomethoxy group at C-2, was investigated. No reaction was observed using 1,4-quinones 8 and 9 bearing an ester group at C-2 whereas use of 1,4-quinones 10 and 11 bearing an acetyl group at C-2 only provided low yields of the silyloxythiophenes 15 and 16 resulting from electrophilic substitution of the silyloxythiophene by the 1,4-quinone. Use of the Lewis acids InCl3, Cu(OTf)2 and BF3??Et2O were investigated in an effort to improve the yield of the desired annulation reaction. BF3??Et2O proved to be the optimum catalyst for the synthesis of thiolactone naphthofuran adducts 14 and 18 from 1,4-naphthoquinones 9 and 11, respectively. Reaction of 2-tert-butyldimethylsilyloxythiophene 2 with 1,4-benzoquinones 8 and 10 bearing a carbomethoxy or an acetyl group at C-2, respectively, afforded thiolactone benzofuran adducts 13 and 17, respectively, catalyzed by either InCl3 or Cu(OTf)2. Addition of 2-tert-butyldimethylsilyloxythiophene 2 to 3-acetyl-5-methoxy-1,4-naphthoquinone 12 afforded adduct 19 that underwent oxidative rearrangement to thiolactone pyranonaphthoquinone 20 using ceric ammonium nitrate in acetonitrile, thus providing a novel approach for the synthesis of a thia analogue of the pyranonaphthoquinone antibiotic kalafungin.

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