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The Potential Of Quinoline Derivatives For The Treatment Of Toxoplasma Gondii Infection., Sirinart Ananvoranich Oct 2014

The Potential Of Quinoline Derivatives For The Treatment Of Toxoplasma Gondii Infection., Sirinart Ananvoranich

Chemistry and Biochemistry Publications

Here we reported our investigation, as part of our drug repositioning effort, on anti-Toxoplasma properties of newly synthesized quinoline compounds. A collection of 4-aminoquinoline and 4-piperazinylquinoline analogs have recently been synthesized for use in cancer chemotherapy. Some analogs were able to outperform chloroquine, a quinoline derivative drug which is commonly used in the treatment of malaria and other parasitic infections. Herein 58 compounds containing one or two quinoline rings were examined for their effectiveness as potential anti-Toxoplasma compounds. Of these 58 compounds, 32 were efficient at inhibiting Toxoplasma growth (IC50μM). Five compounds with single and simple quinoline rings exhibited similar …

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A Multi-Scale Computational Study On The Mechanism Of Streptococcus Pneumoniae Nicotinamidase (Spnic), Bogdan F. Ion, Erum Kazim, James Gauld Sep 2014

A Multi-Scale Computational Study On The Mechanism Of Streptococcus Pneumoniae Nicotinamidase (Spnic), Bogdan F. Ion, Erum Kazim, James Gauld

Chemistry and Biochemistry Publications

Nicotinamidase (Nic) is a key zinc-dependent enzyme in NAD metabolism that catalyzes the hydrolysis of nicotinamide to give nicotinic acid. A multi-scale computational approach has been used to investigate the catalytic mechanism, substrate binding and roles of active site residues of Nic from Streptococcus pneumoniae (SpNic). In particular, density functional theory (DFT), molecular dynamics (MD) and ONIOM quantum mechanics/molecular mechanics (QM/MM) methods have been employed. The overall mechanism occurs in two stages: (i) formation of a thioester enzyme-intermediate (IC2) and (ii) hydrolysis of the thioester bond to give the products. The polar protein environment has a significant effect in stabilizing …

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Novel Analogue Of Colchicine Induces Selective Pro-Death Autophagy And Necrosis In Human Cancer Cells, Kristen Elizabeth Larocque, Pamela Ovadje, Sinisa Djurdjevic, Mariam Mehdi, James R. Green, Siyaram Pandey Jan 2014

Novel Analogue Of Colchicine Induces Selective Pro-Death Autophagy And Necrosis In Human Cancer Cells, Kristen Elizabeth Larocque, Pamela Ovadje, Sinisa Djurdjevic, Mariam Mehdi, James R. Green, Siyaram Pandey

Chemistry and Biochemistry Publications

Colchicine, a natural product of Colchicum autumnae currently used for gout treatment, is a tubulin targeting compound which inhibits microtubule formation by targeting fast dividing cells. This tubulin-targeting property has lead researchers to investigate the potential of colchicine and analogs as possible cancer therapies. One major study conducted on an analogue of allocolchicine, ZD 6126, was halted in phase 2 clinical trials due to severe cardio-toxicity associated with treatment. This study involves the development and testing of novel allocolchicine analogues that hold non-toxic anti-cancer properties. Currently we have synthesized and evaluated the anti-cancer activities of two analogues; N-acetyl-O-methylcolchinol (NSC 51046 …

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Multi-Scale Computational Enzymology: Enhancing Our Understanding Of Enzymatic Catalysis, Rami Gherib, Hisham Mohammed Mohammed Dokainish, James Gauld Dec 2013

Multi-Scale Computational Enzymology: Enhancing Our Understanding Of Enzymatic Catalysis, Rami Gherib, Hisham Mohammed Mohammed Dokainish, James Gauld

Chemistry and Biochemistry Publications

Elucidating the origin of enzymatic catalysis stands as one the great challenges of contemporary biochemistry and biophysics. The recent emergence of computational enzymology has enhanced our atomistic-level description of biocatalysis as well the kinetic and thermodynamic properties of their mechanisms. There exists a diversity of computational methods allowing the investigation of specific enzymatic properties. Small or large density functional theory models allow the comparison of a plethora of mechanistic reactive species and divergent catalytic pathways. Molecular docking can model different substrate conformations embedded within enzyme active sites and determine those with optimal binding affinities. Molecular dynamics simulations provide insights into …

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Nicholas Reactions In The Synthesis Of Dicobalt Dibenzocyclooctyne Complexes, Sinisa Djurdjevic, James R. Green Nov 2013

Nicholas Reactions In The Synthesis Of Dicobalt Dibenzocyclooctyne Complexes, Sinisa Djurdjevic, James R. Green

Chemistry and Biochemistry Publications

Hexacarbonyldicobalt complexes of biaryl-substituted 4-methoxybutynones and 4-methoxy-2-butynes undergo intramolecular Nicholas reactions to form dibenzocyclooctyne–Co2(CO)6 complexes in good yields. Reductive decomplexation of the cyclization products is possible, and the method has been applied to a formal synthesis of isoschizandrin.

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The Observation Of Highly Ordered Domains In Membranes With Cholesterol, Clare L. Armstrong, Drew Marquardt, Hannah Dies, Norbert Kučerka, Zahra Yamani, Thad A. Harroun, John Katsaras, An Chang Shi, Maikel C. Rheinstädter Jun 2013

The Observation Of Highly Ordered Domains In Membranes With Cholesterol, Clare L. Armstrong, Drew Marquardt, Hannah Dies, Norbert Kučerka, Zahra Yamani, Thad A. Harroun, John Katsaras, An Chang Shi, Maikel C. Rheinstädter

Chemistry and Biochemistry Publications

Rafts, or functional domains, are transient nano- or mesoscopic structures in the exoplasmic leaflet of the plasma membrane, and are thought to be essential for many cellular processes. Using neutron diffraction and computer modelling, we present evidence for the existence of highly ordered lipid domains in the cholesterol-rich (32.5 mol%) liquid-ordered (l0) phase of dipalmitoylphosphatidylcholine membranes. The liquid ordered phase in one-component lipid membranes has previously been thought to be a homogeneous phase. The presence of highly ordered lipid domains embedded in a disordered lipid matrix implies non-uniform distribution of cholesterol between the two phases. The experimental results are in …

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Bicatalytic Allylation–Cross-Metathesis Reactions As Γ-Carbonyl Cation Equivalents, Jake R. Henkie, Sugadar Dhaliwal, James R. Green Oct 2012

Bicatalytic Allylation–Cross-Metathesis Reactions As Γ-Carbonyl Cation Equivalents, Jake R. Henkie, Sugadar Dhaliwal, James R. Green

Chemistry and Biochemistry Publications

The products corresponding to the reactions of arenes and γ-carbonyl cations may be obtained by a one-pot, bicatalytic process involving InCl3-catalyzed arene allylation and cross metathesis with electron-deficient alkenes. The process is successful with electronically neutral and electron-rich arenes, and modestly Lewis basic donor groups are tolerated with an increase in InCl3 loading from 10 mol% to 15 mol%, and in one case, 20 mol%.

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A Molecular Dynamics (Md) And Quantum Mechanics/Molecular Mechanics (Qm/Mm) Study On Ornithine Cyclodeaminase (Ocd): A Tale Of Two Iminiums, Bogdan F. Ion, Eric Andre Bushnell, Phil De Luna, James Gauld Oct 2012

A Molecular Dynamics (Md) And Quantum Mechanics/Molecular Mechanics (Qm/Mm) Study On Ornithine Cyclodeaminase (Ocd): A Tale Of Two Iminiums, Bogdan F. Ion, Eric Andre Bushnell, Phil De Luna, James Gauld

Chemistry and Biochemistry Publications

Ornithine cyclodeaminase (OCD) is an NAD+-dependent deaminase that is found in bacterial species such as Pseudomonas putida. Importantly, it catalyzes the direct conversion of the amino acid L-ornithine to L-proline. Using molecular dynamics (MD) and a hybrid quantum mechanics/molecular mechanics (QM/MM) method in the ONIOM formalism, the catalytic mechanism of OCD has been examined. The rate limiting step is calculated to be the initial step in the overall mechanism: hydride transfer from the L-ornithine’s Cα–H group to the NAD+cofactor with concomitant formation of a Cα=NH2+ Schiff base with a barrier …

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Alkynedicobalt Complexes In Γ-Carbonyl Cations And Cycloheptynedicobalt Complexes, James R. Green Jun 2012

Alkynedicobalt Complexes In Γ-Carbonyl Cations And Cycloheptynedicobalt Complexes, James R. Green

Chemistry and Biochemistry Publications

This Account describes our work on highly electrophilic γ-carbonyl cations featuring propargyldicobalt cations, cycloheptynedicobalt complexes, and the interconnection between the two systems.
1 Introduction
2 γ-Carbonyl Cations via Iron Allyl Cations
3 γ-Carbonyl Cations via Propargyldicobalt Cations
3.1 Synthesis of Velloziolide
3.2 Synthesis of Microstegiol
4 Synthesis of Cycloheptynedicobalt Complexes
4.1 Synthesis via γ-Carbonyl Cations
4.2 Cycloheptynedicobalt Complexes via [4+3] Cycloaddition Reactions
4.3 Cycloheptynedicobalt Complexes via Ring-Closing Meta­thesis
4.4 Cycloaddition Reactions on Cycloheptynedicobalt Complexes
4.5 Cycloheptynedicobalt Complexes via Intramolecular ­Nicholas Reactions
5 Dehydrotropylium Ion Co2(CO)6 Complex
6 Final Comments

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Co2 Production In The Bromate-1,4-Cyclohexanedione Oscillatory Reaction, Jiamin Feng, James R. Green, Samuel A. Johnson, Jichang Wang Jun 2011

Co2 Production In The Bromate-1,4-Cyclohexanedione Oscillatory Reaction, Jiamin Feng, James R. Green, Samuel A. Johnson, Jichang Wang

Chemistry and Biochemistry Publications

NMR and GC/MS spectroscopy of the organic extracts of the oscillatory bromate-1,4-cyclohexanedione reaction illustrate the presence of ring-opening products 5-(dibromomethylene)-2(5H)-furanone, (E)-5,5,5-tribromo-4-oxo-2-pentenoic acid, and dibromoacetic acid, particularly at elevated temperatures. The loss of a carbon atom from the six-membered ring after ring opening led to gas formation and such a process became more vigorous at >60 °C, with the direct observation of bubbles in a stirred batch reactor. Gravimetric experiments confirm that the amount of carbon dioxide gas produced increases rapidly with reaction temperature. Parallel experiments suggest that the ring-opening process involves the oxidation of brominated benzoquinones by bromate. Copyright © …

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Dehydrotropylium-Co2(Co)6 Ion. Generation, Reactivity And Evaluation Of Cation Stability, Sheida Amiralaei, James Gauld, James R. Green Apr 2011

Dehydrotropylium-Co2(Co)6 Ion. Generation, Reactivity And Evaluation Of Cation Stability, Sheida Amiralaei, James Gauld, James R. Green

Chemistry and Biochemistry Publications

The dehydrotropylium–Co2(CO)6 ion was generated by the action of HBF4 or BF3⋅OEt2 on the corresponding cycloheptadienynol complex, which in turn has been prepared in four steps from a known diacetoxycycloheptenyne complex. The reaction of the cycloheptadienynol complex via the dehydrotropylium–Co2(CO)6 ion with several nucleophiles results in substitution reactions with reactive nucleophiles (N>1) under normal conditions, and a radical dimerisation reaction in the presence of less reactive nucleophiles. Competitive reactions of the cycloheptadienynol complex with an acyclic trienynol complex show no preference for generation of the dehydrotropylium–Co2 …

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Synthesis Of ‘Spacer’-Naproxen [2-(6-Methoxybiphenylen-2-Yl)Propanoic Acid] And -Isonaproxen [2-(7-Methoxybiphenylen-2-Yl)Propanoic Acid], Juan A. González Gómez, James R. Green, Peter C. Vollhardt Apr 2011

Synthesis Of ‘Spacer’-Naproxen [2-(6-Methoxybiphenylen-2-Yl)Propanoic Acid] And -Isonaproxen [2-(7-Methoxybiphenylen-2-Yl)Propanoic Acid], Juan A. González Gómez, James R. Green, Peter C. Vollhardt

Chemistry and Biochemistry Publications

The CpCo(CO)2-catalyzed cocyclization of 1,2-diethynyl- 4-methoxybenzene with alkynes can be applied to the synthesis of ‘spacer’-naproxen [2-(6-methoxybiphenylen-2-yl)propanoic acid] and its 7-methoxy isomer, ‘spacer’-isonaproxen. While unsymmetrical alkynes are incorporated without regioselectivity, the methoxy group in 6-methoxy-2,3-bis(trimethylsilyl)biphenylene directs electrophiles to C-3, thus allowing for regiochemical differentiation between the 2- and 3-positions.

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Vinylogous Nicholas Reactions In The Synthesis Of Icetexane, Faveline, And Related Ring Systems, Izabela Kolodziej, James R. Green Jan 2011

Vinylogous Nicholas Reactions In The Synthesis Of Icetexane, Faveline, And Related Ring Systems, Izabela Kolodziej, James R. Green

Chemistry and Biochemistry Publications

The intramolecular vinylogous Nicholas reactions of aryl substituted acetoxy enyne-Co(2)(CO)(6) complexes afford tricyclic 6,7,6-ring systems and related systems in good yield.

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Nicholas Reactions In The Construction Of Cyclohepta[De]Naphthalenes And Cyclohepta[De]Naphthalenones. The Total Synthesis Of Microstegiol, Rafiq Taj, James R. Green Dec 2010

Nicholas Reactions In The Construction Of Cyclohepta[De]Naphthalenes And Cyclohepta[De]Naphthalenones. The Total Synthesis Of Microstegiol, Rafiq Taj, James R. Green

Chemistry and Biochemistry Publications

The application of the Nicholas reaction chemistry of 2,7-dioxygenated naphthalenes in the synthesis of cyclohepta[de]napthalenes and in the synthesis of (±)-microstegiol (1) is presented. The substitution profile of Nicholas monosubstitution (predominantly C-1) and disubstitution reactions (predominantly 1,6-) on 2,7-dioxygenated napthalenes is reported. Application of a 1,8-dicondensation product and selected C-1 monocondensation products to the construction of cyclohepta[de]naphthalenes by way of ring closing metathesis and intramolecular Friedel−Crafts reactions, respectively, is described. Deprotection of the C-7 oxygen function to the corresponding naphthol allows tautomerization to cyclohepta[de]naphthalene-1-ones upon seven-membered-ring closure in most cases, and replacement …

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Intramolecular Nicholas Reactions In The Synthesis Of Dibenzocycloheptanes. Synthesis Of Allocolchicine Nsc 51046 And Analogues And The Formal Synthesis Of (−)-Allocolchicine, Sinisa Djurdjevic, Fei Yang, James R. Green Dec 2010

Intramolecular Nicholas Reactions In The Synthesis Of Dibenzocycloheptanes. Synthesis Of Allocolchicine Nsc 51046 And Analogues And The Formal Synthesis Of (−)-Allocolchicine, Sinisa Djurdjevic, Fei Yang, James R. Green

Chemistry and Biochemistry Publications

The preparation of dibenzocycloheptyne-Co2(CO)6 complexes by intramolecular Nicholas reactions of biaryl-2-propargyl alcohol-Co2(CO)6 derivatives is described. Reductive decomplexation of the dibenzocycloheptyne-Co2(CO)6 complexes affords the corresponding dibenzocycloheptenes, individual members of which have been employed in a formal total synthesis of (−)-allocolchicine, the preparation of 6,7-dihydro-3,4,9,10,11-pentamethoxy-5H-dibenzo[a,c]cyclohepten-5-one, and the enantioselective total syntheses of NSC 51046 and its 3,8,9,10-tetramethoxy regioisomer.

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Cyclohepta[De]Naphthalenes And The Rearranged Abietane Framework Of Microstegiol Via Nicholas Reaction Chemistry, Rafiq A. Taj, Anusha Abhayawardhana, James R. Green Jan 2009

Cyclohepta[De]Naphthalenes And The Rearranged Abietane Framework Of Microstegiol Via Nicholas Reaction Chemistry, Rafiq A. Taj, Anusha Abhayawardhana, James R. Green

Chemistry and Biochemistry Publications

Nicholas reactions on 2,7-dioxygenated naphthalenes give C-1 monosubstitution and C-1/C-8 disubstitution in most cases. From gamma-carbonyl cation monocondensation product 3b or alkyne-unsubstituted dicondensation product 4a, cyclohepta[de]naphthalenes bearing no substituents, gem-dimethyl substituents, and a ketone function, and the rearranged abietane framework of microstegiol may be prepared.

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Lewis And Protic Acid Mediated Nicholas Reactions Of 3-Acetoxycyclohept-1-En-4-Ynedicobalt Hexacarbonyl: Site Selectivity Of Nucleophile Incorporation, Joseph Dimartino, James R. Green Jan 2006

Lewis And Protic Acid Mediated Nicholas Reactions Of 3-Acetoxycyclohept-1-En-4-Ynedicobalt Hexacarbonyl: Site Selectivity Of Nucleophile Incorporation, Joseph Dimartino, James R. Green

Chemistry and Biochemistry Publications

Nicholas reactions on the cation derived from the cyclic allylic acetate alkynedicobalt complex 1 favour the gamma-site kinetically for most nucleophiles, with increasing amounts of of-products in cases with greater nucleophilicity. Some regiocontrol in introduction of a specific nucleophilic fragment is possible by using different nucleophiles. Under conditions where reversibility is possible, the thermodynamically favoured site is exclusively gamma-. (c) 2005 Elsevier Ltd. All rights reserved.

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Benzocycloheptynedicobalt Complexes By Intramolecular Nicholas Reactions, Y. Ding, James R. Green Jan 2005

Benzocycloheptynedicobalt Complexes By Intramolecular Nicholas Reactions, Y. Ding, James R. Green

Chemistry and Biochemistry Publications

Lewis acid mediated intramolecular Nicholas reactions of aryl (Z)-enyne propargyl acetate-CO2(CO)(6) complexes 1 afford benzocycloheptenyne-CO2(CO)(6) complexes 2 and their heterocyclic analogues.

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Intramolecular Pauson-Khand Reactions Of Cycloheptynedicobalt Complexes, Ahmed B. Mohamed, James R. Green, Jason Masuda Jan 2005

Intramolecular Pauson-Khand Reactions Of Cycloheptynedicobalt Complexes, Ahmed B. Mohamed, James R. Green, Jason Masuda

Chemistry and Biochemistry Publications

Cycloheptyne-Co-2(CO)(6) complexes bearing alkenes tethered by oxygen, sulfur, and nitrogen atoms undergo Pauson-Khand reactions to afford tricyclic compounds containing a fused 7,5-ring system.

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Mono- And Disubstitutions Of (Hepta-2,5-Diyne-1,7-Diol) Bis(Dicobalt) Derivatives - Selectivity In Nicholas Reactions, Richard Guo, Romelo Gibe, James R. Green Jan 2004

Mono- And Disubstitutions Of (Hepta-2,5-Diyne-1,7-Diol) Bis(Dicobalt) Derivatives - Selectivity In Nicholas Reactions, Richard Guo, Romelo Gibe, James R. Green

Chemistry and Biochemistry Publications

Bis(hexacarbonyldicobalt) complexes of benzyl ether - methyl ether or benzyl ether - acetate derivatives of hepta-2,5-diyne-1,7-diols undergo selective Lewis-acid-mediated Nicholas reactions with enol silanes, silyl ketene acetals, and allylstannanes, preferentially replacing the methyl ether or acetate function. Hydride nucleophiles are similarly incorporated selectively using a benzyl ether - alcohol derivative. Subsequent Nicholas reaction at the benzyloxy-bearing site may be accomplished with an identical or a different nucleophile, affording skipped 1,4-diyne-Co-4(CO)(12) complexes. In instances of lower selectivity for monosubstitution reactions with benzyl ethers, reverting to the use of a menthyl ether - methyl ether complex gives much improved selectivity for methyl …

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Tandem 4+3 Cycloaddition/Nucleophilic Trapping Reactions Of Butyne-1,4-Diether Dicobalt Hexacarbonyl Complexes, Yafan Lu, James R. Green Jan 2001

Tandem 4+3 Cycloaddition/Nucleophilic Trapping Reactions Of Butyne-1,4-Diether Dicobalt Hexacarbonyl Complexes, Yafan Lu, James R. Green

Chemistry and Biochemistry Publications

Butyne-1,4-diether hexacarbonyldicobalt complexes 1 undergo Lewis acid mediated 4+3 cycloadditions with allylsilanes, incorporating halide from the Lewis acid to give halocycloheptynes 3, 6, 7. A phenyl group may be incorporated in place of the halogen (to give 8) by use of benzene as solvent and with B(C6F5)(3) as the Lewis acid; chlorobenzene and toluene also participate in the process.

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Cycloheptenyne Dicobalt Hexacarbonyl Complexes By Ring Closing Metathesis, James R. Green Jan 2001

Cycloheptenyne Dicobalt Hexacarbonyl Complexes By Ring Closing Metathesis, James R. Green

Chemistry and Biochemistry Publications

Hexacarbonyldicobalt complexes of cycloheptenynes (4) may be prepared by the ring closing metathesis of the corresponding acyclic dienes (2) using Grubbs' catalyst, (Cy3P)(2)Cl2Ru=CHPh. A cyclooctenyne complex (8) has also been prepared in the strictly analogous manner.

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