254 results for Brimble, Margaret, Journal article

  • Kinetic Resolution in the Asymmetric Dihydroxylation of 1,7-Dioxaspiro[5.5]undec-4-enes,

    Brimble, Margaret; Johnston, Andrew (1997)

    Journal article
    The University of Auckland Library

    The asymmetric dihydroxylation of unsaturated spiroacetals 1, 2, 3 was effected using the cinchona alkaloid ligands (DHQ)2-PHAL. (DHQD)2-PHAL and DHQ-IND, DHQD-IND with OSO4, K3Fe(CN)6 and methanesulfonamide. Kinetic resolution of the spiroacetals was achieved and the reactions were monitored by chiral gas chromatography.

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  • Diastereoselective Synthesis of Substituted 4-Piperidones and 4-Piperidols Using a Double Mannich Reaction

    Chan, Y; Guthmann, Holger; Brimble, Margaret; Barker, David (2008)

    Journal article
    The University of Auckland Library

    A simple and efficient synthesis of polysubstituted 4-piperidones was achieved from the double Mannich reaction of beta-keto esters and bisaminol ethers. The reaction is highly diastereoselective, as is the subsequent hydride reduction, to give polysubstituted 4-piperidols.

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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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  • Enantioselective Synthesis of the Apple Aroma Constituent 1,3,3-Trimethyl-2,7-dioxabicyclo[2.2.1]heptane via Asymmetric Dihydroxylation

    Brimble, Margaret; Rowan, DD; Spicer, Julie (1995)

    Journal article
    The University of Auckland Library

    The enantiomers of 1,3,3-trimethyl-2,7-dioxabicyclo[2.2.1]heptane (1) were prepared in two steps from 6-methylhept-5-en-2-one using Sharpless asymmetric dihydroxylation.

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  • FORMAL SYNTHESIS OF THE JUGLOMYCINS

    Brimble, Margaret; IRELAND, E (1994-11-07)

    Journal article
    The University of Auckland Library

    5′-Deoxyjuglomycin A 3 and 5′-methoxyjuglomycin A 4 have been synthesized via oxidative fragmentation of furo[3,2-b]naphtho[2,1-d]furans 9 and 10 respectively. Addition of 2-trimethylsiloxyfuran 5 to naphthoquinone sulfides 7, 8 afforded the key adducts 9, 10 which then underwent fragmentation to the quinone sulfides 11, 14 using ceric ammonium nitrate. Treatment of the trimethylsilyl derivatives 13, 15 of the sulfides 11, 14 with meta-chloroperoxybenzoic acid effected conversion into the sulfoxides 16, 18 which then underwent smooth desulfurization using tributyltin hydride to the quinones 21, 23. Finally, hydrolysis of the trimethylsilyl group completed the synthesis of 5′-deoxyjuglomycin A 3 and 5′-methoxyjuglomycin A 4.

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  • H-1 and C-13 NMR data for C-6 substituted 3-azabicyclo[3.3.1]nonane-1-carboxylates

    Goodall, Kirsten; Brimble, Margaret; Barker, David (2006)

    Journal article
    The University of Auckland Library

    The 1H and 13C NMR spectra of 3-azabicyclo[3.3.1]nonanes with various oxygenated substituents at C-6 were assigned using 1D (DEPT) and 2D (COSY, HSQC, HMBC, NOESY) experiments. Close examination of this NMR data details the effects of substitution and stereochemistry at C-6 in these compounds.

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  • HIGHLY STEREOSELECTIVE SYN-HYDROXYLATION OF SPIROKETALS

    Brimble, Margaret; NAIRN, MR; WU, YQ (1991-08-05)

    Journal article
    The University of Auckland Library

    The highly stereoselective syn-hydroxylation of unsaturated spiroketals (3,5) is reported.

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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 and Reactivity of beta-Methoxymethyl Enecarbamates

    O'Connor, Patrick; Marino, MG; Gueret, SM; Brimble, Margaret (2009)

    Journal article
    The University of Auckland Library

    β-Methoxymethyl enecarbamates (e.g., 1) have been prepared in a single step from α-methoxy carbamates. In the presence of a mild Lewis acid, compound 1 underwent substitution with a variety of nucleophiles including indoles, electron-rich aromatics, silyl enol ethers, and 2-trimethylsilyloxyfuran.

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  • SYNTHESIS OF 5-EPI-ARIZONIN-B1 AND 5-EPI-ARIZONIN-C1

    Brimble, Margaret; PHYTHIAN, SJ (1993-09-03)

    Journal article
    The University of Auckland Library

    The first synthesis of 5-epi-arizonin B1 (19) and 5-epi-arizonin C1 (18) is described in which the key step involves rearrangement of a furo[3,2-b]naphtho[2,1-d]furan (16) to a furo[3,2-b]naphtho[2,3-d]pyran (17). Regioselective synthesis of naphthoquinone (15) was crucial to this synthetic strategy. The first synthesis of 5-epi-arizonin B1 and 5-epi-arizonin C1 is described.

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  • Synthesis of a C8 oxygenated pyranonaphthoquinone: a useful precursor to dimeric pyranonaphthoquinones

    Bachu, P; Sperry, Jonathan; Brimble, Margaret (2008)

    Journal article
    The University of Auckland Library

    The synthesis of a pyranonaphthoquinone bearing an oxygenated substituent at C8 is reported. The oxygen substituent at C8 provides a key functionality for use as a homocoupling precursor for the synthesis of a dimeric pyranonaphthoquinone.

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  • Synthesis of an actinorhodin monomer

    Brimble, Margaret; Duncalf, LJ; Phythian, SJ (1995-12-11)

    Journal article
    The University of Auckland Library

    The first synthesis of the monomeric unit of the dimeric pyranonaphthoquinone antibiotic γ-actinorhodin 2 is reported. © 1995 Elsevier Science Ltd.

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  • A Short Enantioselective Synthesis of the Topoisomerase II (+)-Eleutherin

    Gibson, Jennifer; Andrey, O; Brimble, Margaret (2007)

    Journal article
    The University of Auckland Library

    A Hauser-Kraus annulation was used as a key step for the concise enantioselective synthesis of the topoisomerase II inhibitor (+)-eleutherin.

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  • [2R*,5S*,6S*]-2-methyl-1,7-dioxaspiro[5.5]undec-2-en-5-ol

    Brimble, Margaret; Johnston, AD (1997-01-01)

    Journal article
    The University of Auckland Library

    The reaction and the product ratio shown in the scheme was reported [1]. The two products (2 [1] and 3) were separated by flash chromatography using hexane-ethyl acetate (6:4) as eluent to afford the title compound [2R*,5S*,6S*]-2-Methyl-1,7-dioxaspiro[5.5]undec-2-en-5-ol (3 in the scheme) as a colourless oil (20 mg, 16%).

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  • [2R*,5S*,6S*]-2-methyl-1,7-dioxaspiro[5.5]undec-3-en-5-ol

    Brimble, Margaret; Johnston, AD (1997-01-01)

    Journal article
    The University of Auckland Library

    Isomerisations of epoxides to allylic alcohols have been effected by strong non-nucleophilic bases such as lithium dialkylamides. The formation of allylic alcohols from the reaction of epoxides with lithium amide bases appears to proceed via a b-elimination pathway when the reaction is performed in relatively non-polar solvents [1].

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  • Allylic amination by the Lewis-acid-mediated ene reaction of diethyl azodicarboxylate with alkenes

    Brimble, Margaret; Heathcock, CH (1993)

    Journal article
    The University of Auckland Library

    The ene reaction2 plays an important role in organic synthesis as a method for carbon-carbon bond formation. Because there are a variety of enophiles available, the ene reaction converts readily accessible alkenes into more functionalized compounds in which the double bond undergoes allylic transposition. ...

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  • Improved Synthesis of the Benzyne Precursor 2-(Trimethylsilyl)phenyl Trifluoromethanesulfonate

    Atkinson, Darcy; Sperry, Jonathan; Brimble, Margaret (2010)

    Journal article
    The University of Auckland Library

    An alternate procedure for the preparation of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate, a coveted benzyne precursor, is described. Modifications to existing methods result in a dramatic reduction in the overall reaction time and eliminate the use of organolithium reagents. This new procedure proceeds in four steps in 81% overall yield from 2-chlorophenol.

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  • 1,4-Addition of 2-trimethylsilyloxyfuran to quinones: A facile route to the furo[3,2-b]benzofuran nucleus

    Brimble, Margaret; Gibson, JJ; Baker, R; Brimble, MT; Kee, AA; O'Mahony, MJ (1987)

    Journal article
    The University of Auckland Library

    The uncatalysed addition of 2-trimethylsilyloxyfuran (3) to a range of activated quinones (4) and (6) yields the crystalline adducts (5) and (7) in 51-91% yield. This novel furofuran-annulation to a quinone system provides a facile entry to the furo[3,2-b]benzofuran ring system. © 1987.

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  • Stereoselective Synthesis of 4-Substituted 4-Hydroxypiperidines via Epoxidation-Ring Opening of 4-Methylenepiperidines

    Mckay, VA; Thompson, SJ; Tran, PM; Goodall, KJ; Brimble, Margaret; Barker, David (2010)

    Journal article
    The University of Auckland Library

    Reaction of 9-methylene-3-azabicyclo[3.3.1]nonanes with trifluoroperacetic acid results in stereoselective epoxidation to give the syn-epoxide. Intermolecular hydrogen bonding between the protonated tertiary amine and the peracid is responsible for the high levels of stereoselectivity.

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  • Peripheral administration of a novel diketopiperazine, NNZ 2591, prevents brain injury and improves somamtosensory-motor function following hypoxia-ischemia in adult rats.

    Guan, Jian; Mathai, Sam; Harris, Paul; Wen, Jingyuan; Zhang, J; Brimble, Margaret; Gluckman, Peter (2007)

    Journal article
    The University of Auckland Library

    The current study describes the neuroprotective effects of an endogenous diketopiperazine, cyclo-glycyl-proline (cyclic GP), in rats with hypoxic-ischemic brain injury and the pre-clinical development of an analogue, cyclo-L-glycyl-L-2-allylproline (NNZ 2591), modified for improved bioavailability. The compounds were given either intracerebroventricularly or subcutaneously 2h after hypoxia-ischemia. Histology, immunohistochemistry and behavior were used to evaluate treatment effects. The central uptake of NNZ 2591 was also examined in normal and hypoxic-ischemic injured rats by HPLC-mass spectrometry. Central administration of cyclic GP or NNZ 2591 reduced the extent of brain damage in the lateral cortex, the hippocampus and the striatum (p<0.0001). NNZ 2591 treatment not only reduced both caspase-3 mediated apoptosis and microglial activation but also enhanced astrocytic reactivity, which may mediate its protective effect. The pharmacokinetic profile and potent long-term protective effects of NNZ 2591 suggests its utility for the treatment of ischemic brain injury and other neurological conditions requiring chronic intervention.

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