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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  • DIHYDROXYLATION OF 1,7-DIOXASPIRO[5.5]UNDEC-4-ENES

    Brimble, Margaret; NAIRN, MR (1993-01-01)

    Journal article
    The University of Auckland Library

    The highly stereoselective syn-hydroxylation of the unsaturated spiro acetals (4-8) with osmium tetraoxide is reported. In all cases, hydroxylation occurred from the beta-face giving the diols in which the hydroxy group at C5 is axial and anti to the C-O bond of the neighbouring tetrahydropyran ring.

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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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  • 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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  • Pyranonaphthoquinones ??? isolation, biology and synthesis: an update

    Naysmith, BJ; Hume, Paul; Sperry, Jonathan; Brimble, Margaret (2017-01)

    Journal article
    The University of Auckland Library

    Covering: 2008 to 2015. A review on the isolation, biological activity and synthesis of pyranonaphthoquinone natural products from 2008-2015 is providedThis review discusses the isolation, biological activity and synthesis of pyranonaphthoquinone natural products, covering the years 2008-2015. The pyranonaphthoquinones are a group of metabolites sharing a common naphtho[2,3-c]pyran-5,10-dione ring system that have been isolated from a wide range of microorganisms, plants and insects. In addition to their synthetically challenging molecular structures, pyranonaphthoquinones exhibit a wide array of biological activity, including anti-bacterial, anti-fungal and anti-cancer properties. The therapeutic potential of these compounds has led to a dynamic interplay between total synthesis and biological evaluation.

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  • Structure activity relationship study on the peptide hormone preptin, a novel bone-anabolic agent for the treatment of osteoporosis

    Amso, Z; Kowalczyk, Renata; Watson, M; Park, YE; Callon, Karen; Musson, David; Cornish, Jillian; Brimble, Margaret (2016-10-21)

    Journal article
    The University of Auckland Library

    Preptin is a 34-residue pancreatic hormone shown to be anabolic to bone in vitro and in vivo. The bone activity of preptin resides within the (1-16) N-terminal fragment. Due to its peptidic nature, the truncated fragment of preptin is enzymatically unstable; however it provides an attractive framework for the creation of stable analogues using various peptidomimetic techniques. An alanine scan of preptin (1-16) was undertaken which showed that substitution of Ser at position 3 or Pro at position 14 did not inhibit the proliferative activity of preptin in primary rat osteoblasts (bone-forming cells). Importantly, Ser-3 to Ala substitution also showed a significant activity on osteoblast differentiation in vitro and increased the formation of mineralised bone matrix. Additional modifications with non-proteinogenic amino acids at position 3 improved the stability in liver microsomes, but diminished the osteoblast proliferative activity. In addition, to provide greater structural diversity, a series of macrocyclic preptin (1-16) analogues was synthesised using head-to-tail and head-to-side chain macrolactamisation as well as ring-closing metathesis. However, a detrimental effect on osteoblast activity was observed upon macrocyclisation.

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  • Enantioselective Synthesis of BE Ring Analogues of Methyllycaconitine

    Dickson, E; Pilkington, L; Brimble, Margaret; Barker, David (2016-01-21)

    Journal article
    The University of Auckland Library

    The enantioselective synthesis of decahydroquinolines mimicking the BE rings of methyllycaconitine (MLA) is reported. The analogues were synthesised via a one-pot cyclisation using ethyl alpha-(bromomethyl) acrylate, (R)-1-phenylethanamine and cyclohexanone to form chiral octahydroquinolines which can be selectively hydrogenated to form the 3-substituted-decahydroquinolines with the same stereochemistry found in MLA. The amine and ketone components in the one-pot reaction can also be altered to provide access to structurally related heterocycles.

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  • Multifunctional thermoresponsive designer peptide hydrogels

    De Leon Rodriguez, Luis Manuel; Hemar, Yacine; Mo, G; Mitra, Alok; Cornish, Jillian; Brimble, Margaret (2017-01-01)

    Journal article
    The University of Auckland Library

    We report the synthesis and characterization of multifunctional peptides comprised of a hydrogel forming ??-sheet peptide segment and a matrix metalloproteinase 2 substrate containing a propargylglycinyl linker that is further derivatized with an RGD peptide sequence via ???click??? chemistry. In contrast to currently known systems, these multifunctional peptides formed gels that are stiffer than those formed by their respective precursors. All the peptides showed reversible thermoresponsive properties, which render them as suitable lead systems for a variety of possible biomedical applications. Statement of Significance In general, it has been frequently observed that chemical biofunctionalization of peptide hydrogels adversely affects peptide assembly, hydrogel formation or mechanical properties, which severely compromises their application. A functionalization protocol that allows to generate peptide hydrogels that display significantly improved mechanical properties over their unfunctionalized counterparts is reported in this work. These peptides also showed thermoresponsive viscoelastic characteristics, including an example of a peptide hydrogel that displays lower critical solution temperature behaviour.

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