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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  • 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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  • 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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  • 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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  • Growth Habit Modification of Ice Crystals Using Antifreeze Glycoprotein (AFGP) Analogues

    Peltier, Raoul; Evans, Clive; DeVries, AL; Brimble, Margaret; Dingley, Andrew; Williams, David (2010-12)

    Journal article
    The University of Auckland Library

    The research reported here considers the modification of ice crystal growth habit using analogues of antifreeze glycoproteins compounds that control the growth of ice crystals in the blood of Antarctic fishes A range of analogues of the smallest antifree e glycoprotein (AFGP8 Ala-Ala-Thr-Ala-Ala-Thr-Pro-Ala-Thr-Ala-Ala-Thr-Pro-Ala) were synthesized all of which have either N-acetyl-galactosamme or galactose moieties attached to their threonines instead of the native galactose-N acetyl-galactosamine disaccharide We also synthesized analogues in which the prolines wet e substituted with alanines in the protein sequence The analogues were systematically studied for their effects on ice crystal shape and their effects when combined with a range of salts chosen across the Hofmeister series A simple H-1 NMR freezing experiment was used to detect adsorption onto ice and indicate differences in water proton hydrogen bonding CD spectroscopy highlighted the role of the terminal galactoe, the proline residues, and the N-acetylamine group in modifying the solution conformation The results illustrate a delicate balance between the effects of hydrophobic and hydrophilic groups on the glycoprotein and the interactions between the glycoprotein, a developing ice crystal, and water We demonstrate three ways of modulating the ice crystal shape by changing the adsorbent concentration, by changing the adsorbent structure, or by altering the interaction of the glycoprotein with liquid water through the use of simple solution additives We show a continuum of behavior between no shape modification and no thermal hysteresis 10 a strong shape modification and a significant thermal hysteresis, and we relate the results to kinetic models for antifreeze activity

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  • Synthesis and antifreeze activity of fish antifreeze glycoproteins and their analogues

    Peltier, Raoul; Brimble, Margaret; Wojnar, Joanna; Williams, David; Evans, Clive; DeVries, AL (2010)

    Journal article
    The University of Auckland Library

    Fishes from both Arctic and Antarctic waters produce antifreeze glycoproteins (AFGPs) that modify and inhibit the growth of ice crystals, allowing them to survive in extreme cold conditions. These glycoproteins exhibit thermal hysteresis activity, i.e. they work in a non-colligative manner, separating the melting and freezing points of a solution. Such compounds have many potential applications; unfortunately their development is hampered by the difficulty of obtaining pure material. The synthesis of AFGPs is therefore a challenge that numerous groups have been tackling. The AFGPs consist predominantly of a repetitive three amino acid unit (Ala-Ala-Thr)(n) with the disaccharide beta-D-galactosyl-(1-3)-alpha-D-N-acetylgalactosamine attached to the hydroxyl oxygen of each threonine residue. A large number of analogues have also been synthesized in order to find compounds that exhibit the same activity but that are easier to prepare. Starting from the early years of the AFGP discovery and including the more recent research, this perspective summarizes the different routes used to synthesize native AFGPs and lists the most relevant analogues synthesized, along with some information on their synthesis and their antifreeze activity, if evaluated. In this perspective we have taken special care to differentiate compounds that induce thermal hysteresis, compounds that modify the normal growth habit of ice crystals, and compounds that exhibit recrystallization inhibition properties.

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  • Synthesis of bis-spiroacetal ring systems

    Brimble, Margaret; Fares, FA (1999)

    Journal article
    The University of Auckland Library

    A review of methods to synthesise tricyclic bis-spiroacetal ring systems is presented.

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  • (+/-)-2 '-phenylcyclohexanespiro-4 '-(azepano[1,2-b] isoxazolidine)

    crimmins, D; Choi, Ka; Boyd, Peter; Brimble, Margaret (2008)

    Journal article
    The University of Auckland Library

    In the crystal structure of the racemic title isoxazolidine, C19H27NO, the relative stereochemistry between the phenyl group and the bridgehead H atom is shown to be syn. There are two molecules in the asymmetric unit, one of which is the 7R*,13R* enantiomer, and one of which is the 7S*,13S* enantiomer. These enantiomers adopt different orientations of the phenyl ring with respect to the isoxazolidine ring, with C-C-C-C torsion angles of 63.6 (4) and 86.8 (4)??, respectively. In both enantiomers, the six-membered ring adopts a chair conformation, while the seven-membered ring adopts a twist-chair conformation.

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  • (+/-)-Cyclohexane-1,2-diyl bis(4-nitrobenzoate)

    Tong, Sok; Barker, David; Choi, Ka; Boyd, Peter; Brimble, Margaret (2008)

    Journal article
    The University of Auckland Library

    The crystal structure of the title compound, C20H18N2O8, has been investigated to establish the relative stereochemistry between the ester groups. The cyclohexane ring adopts a chair conformation, in which the two ester groups occupy the adjacent equatorial positions in a trans relationship with each other. The molecules assemble in the crystal as chains along the c axis via C-H center dot center dot center dot pi interactions between the cyclohexane ring and a pair of nitrophenyl rings of the neighbouring molecule. Also observed are pi-pi stacking interactions between the nitrophenyl rings of neighbouring chains, with a perpendicular distance between these rings of 3.409 angstrom and a slippage of 0.969 angstrom.

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  • Enantioselective Synthesis of the 3C-Protease Inhibitor (-)-Thysanone using a Staunton-Weinreb Annulation Strategy

    Sperry, Jonathan; Yuen, Tsz; Brimble, Margaret (2009)

    Journal article
    The University of Auckland Library

    The total synthesis of (-)-thysanone is described. The key step involves the addition of an o-toluate anion to a lactone to create the naphthopyran framework (Staunton-Weinreb annulation). This synthesis further confirms the absolute stereochemistry of the natural product to be 1R,3S.

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  • A double Mannich approach to the synthesis of substituted piperidones-application to the synthesis of substituted E-ring analogues of methyllycaconitine

    Chan, YM; Balle, J; Sparrow, JK; Boyd, Peter; Brimble, Margaret; Barker, David (2010-08-28)

    Journal article
    The University of Auckland Library

    The double Mannich reaction of acyclic alpha,gamma-substituted beta-keto esters and bis(aminol) ethers gives substituted 3,5-substituted-4-piperidones with high levels of diastereoselectivity. These piperdiones can be easily transformed into substituted E-ring analogues of the delphinium alkaloid methyllycacotine. (C) 2010 Elsevier Ltd. All rights reserved.

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