Co-reporter:Geoffrey W. Nelson;Emily M. Parker;Kulveer Singh;Christopher F. Blanford;John S. Foord
Langmuir October 13, 2015 Volume 31(Issue 40) pp:11086-11096
Publication Date(Web):2017-2-22
DOI:10.1021/acs.langmuir.5b01644
Polystyrene thin films were functionalized using a facile two-step chemical protocol involving carbene insertion followed by azo-coupling, permitting the introduction of a range of chemical functional groups, including aniline, hexyl, amine, carboxyl, phenyl, phosphonate diester, and ethylene glycol. X-ray photoelectron spectroscopy (XPS) confirmed the success of the two-step chemical modification with a grafting density of at least 1/10th of the typical loading density (1014–1015) of a self-assembled monolayer (SAM). In situ, real-time quartz crystal microbalance with dissipation (QCM-D) studies show that the dynamics of binding of bovine serum albumin (BSA) are different at each modified surface. Mass, viscoelastic, and kinetic data were analyzed, and compared to cheminformatic descriptors (i.e., c log P, polar surface area) typically used for drug discovery. Results show that functionalities may either resist or adsorb BSA, and uniquely influence its adsorption dynamics. It is concluded that carbene-based surface modification can usefully influence BSA binding dynamics in a manner consistent with, and more robust than, traditional systems based on SAM chemistry.
Co-reporter:Kaylie J. Smith, Ian D.H. Towle, Mark G. Moloney
European Polymer Journal 2017 Volume 96(Volume 96) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.eurpolymj.2017.09.007
•The dispersion co-polymerization of PAEK polymers is reported.•They are synthetically readily available by Lewis acid-mediated Friedel-Crafts polymerization.•The polymers have been characterised by combustion analysis, inherent viscosity, DSC, and NMR analysis.•They exhibit suitable polymeric characteristics for engineering materials.A range of particulate polyaryletherketone polymers and copolymers, incorporating ether-imide, sulfone, naphthalene, and aliphatic functionalities, along with branching monomers, may be successfully produced by a dispersion polymerisation process, provided that the reaction parameters are optimised. This significantly expands the range of monomers suitable for application in the Friedel Crafts dispersion polymerisation process.Download high-res image (77KB)Download full-size image
Co-reporter:Song Wei Benjamin Tan;Christina L. L. Chai
Organic & Biomolecular Chemistry 2017 vol. 15(Issue 8) pp:1889-1912
Publication Date(Web):2017/02/22
DOI:10.1039/C6OB02828D
Mono and dihydroxypyrrolidinones are readily available by direct oxygenation of a pyroglutamate-derived bicyclic lactam with high diastereoselectivity, and these may be manipulated further in protected or unprotected form by Grignard addition to a pendant Weinreb amide to give acylhydroxypyrrolidinones, which are analogues of the natural product, pramanicin. Preliminary bioassay against S. aureus and E. coli indicated that some compounds exhibit selective Gram-negative antibacterial activity, and may offer promise for the development of novel systems suitable for antibacterial drug development.
Co-reporter:Pengfei Yang
RSC Advances (2011-Present) 2017 vol. 7(Issue 47) pp:29645-29655
Publication Date(Web):2017/06/05
DOI:10.1039/C7RA05258H
A bis(diaryldiazomethane) substituted with amino groups was synthesized and used for the surface modification of diverse materials, such as polystyrene, polyethylene, titanium dioxide, and aluminum plate, giving amino-functionalized materials. These were subsequently reacted with phenyl isocyanate to give urea-functionalized materials, so that hydrogen peroxide could be reversibly bound, giving in turn antibacterial materials with high activity. These functionalized materials were characterized using a combination of XPS, IR, and NMR spectroscopy, and clear evidence for the crosslinking on the surface of materials was achieved. The crosslinking reaction in the deposited layer contributed to higher loadings of hydrogen peroxide, and hence the antibacterial activity of urea-functionalized materials significantly increased. This approach gives a new protocol to prepare high loading antiseptic/antibacterial materials and surfaces.
Co-reporter:Laia Josa-Culleré;Christopher Towers;Amber L. Thompson
European Journal of Organic Chemistry 2017 Volume 2017(Issue 47) pp:7055-7059
Publication Date(Web):2017/12/22
DOI:10.1002/ejoc.201701393
Weinreb amide derivatives of tetramates may be effectively accessed by chemoselective Dieckmann reaction, and further react with Grignards in a fully chemoselective reaction, giving rise to unsaturated acyl derivatives not easily available by other routes. These systems are strong chelators of calcium, and some show potent activity against Gram positive bacteria, and one is a first-in-class proteasome inhibitor.
Co-reporter:Tharindi D. Panduwawala, Sarosh Iqbal, Rémi Tirfoin and Mark G. Moloney
Organic & Biomolecular Chemistry 2016 vol. 14(Issue 19) pp:4464-4478
Publication Date(Web):12 Apr 2016
DOI:10.1039/C6OB00557H
Chemoselective Dieckmann cyclisation reactions on N-malonyl thiazolidine templates derived from cysteine and pivaldehyde or aromatic aldehydes may be used to access bicyclic tetramates, for which different pathways operate as a result of differing ring-chain tautomeric behaviour of the respective intermediate imines.
Co-reporter:Kaylie J. Smith, Ian D. H. Towle and Mark G. Moloney
RSC Advances 2016 vol. 6(Issue 17) pp:13809-13819
Publication Date(Web):27 Jan 2016
DOI:10.1039/C5RA25253A
A range of particulate poly(ether ketone ketone)s (PEKKs) have been synthesised by a room temperature Friedel–Crafts dispersion polymerisation. Their properties, including glass transition, melting and crystallisation temperatures, the degree of crystallinity and particle size, were readily controlled by altering the ratio of 1,3- to 1,4-units in the polymer backbone. The bulk polymer properties are comparable to materials produced by alternative methods and the polymers are highly melt stable. Unusually, all PEKKs are highly crystalline as produced, although some become amorphous on further processing. Evidence was obtained which is consistent with the particulate product being formed by a seeding mechanism, from aluminium(III) seeding particles which are formed in situ.
Co-reporter:Kaylie J. Smith, Ian D.H. Towle, James F. Pratte, Robin K. Maskell, Mark G. Moloney
European Polymer Journal 2016 Volume 84() pp:538-549
Publication Date(Web):November 2016
DOI:10.1016/j.eurpolymj.2016.09.061
•The dispersion polymerisation of amine-terminated PEEK polymers is reported.•They are synthetically readily available by Lewis acid-mediated Friedel-Crafts polymerisation.•The polymers have been characterised by combustion analysis, inherent viscosity, DSC, SEM and fracture analysis.•They exhibit suitable polymeric characteristics for engineering materials.Amine end-capped polyaryletherketones (PAEKs) are available by a dispersion process using a protection-deprotection strategy with an end-capping aminoaromatic derivative which adds no further steps to the dispersion polymerisation method. A model compound approach was employed to demonstrate successful amine attachment to the polymer, together with its compatibility and suitability within the polymer system. This approach was also successful for linear and trifunctional versions. Scale-up of the PAEK dispersion synthesis to 300 g batches was achieved. Amine end-capped poly(ether ketone ketone) (PEKK) with 100:0, 80:20, 60:40 terephthaloyl (T):isophthaloyl (I) ratios, along with branched PEKK and PEKK-imide copolymers, were synthesised. Mechanical analysis confirmed a substantial increase in fracture toughness on incorporation of the functionalised PEKK particles in an epoxy resin laminate when compared to non-functionalised PEKK particles.
Co-reporter:Céline Shepherd, Emina Hadzifejzovic, Fatma Shkal, Kerstin Jurkschat, Jonathan Moghal, Emily M. Parker, Montree Sawangphruk, Daniel R. Slocombe, John S. Foord, and Mark G. Moloney
Langmuir 2016 Volume 32(Issue 31) pp:7917-7928
Publication Date(Web):July 15, 2016
DOI:10.1021/acs.langmuir.6b02013
Methods for chemical surface functionalization for carbon black (CB) nanoparticles were studied to produce (CB)/polypropylene (PP) nanocomposites with superior electrical and thermal properties. Nanoparticle dispersion is known to directly control the extent to which nanocomposites maximize the unique attributes of their nanoscale fillers. As a result, tailored nanoparticle surface chemistry is a widely utilized method to enhance the interfacial interactions between nanoparticles and polymer matrices, assisting improved filler dispersion. In this work, a rapid chemical functionalization approach using a number of diarylcarbene derivatives, followed by the azo-coupling of substituted diazonium salts, for the covalent introduction of selected functional groups to the CB surface, is reported. Characterization of the modified CB by XPS, TGA, CHN, and ATR-IR collectively confirmed surface functionalization, estimating surface grafting densities of the order of 1013 and 1014 molecules/cm2. Nanocomposites, synthesized by solvent mixing PP with pristine and modified CB, demonstrated macroscopic property changes as a result of the nanoparticle surface functionalization. Pronounced improvements were observed for PP nanocomposites prepared with a dodecyl-terminated diaryl functionalized CB, in which TEM analysis established improved nanofiller dispersion owing to the enhanced CB-PP interfacial interactions in the nanocomposite. Observed dielectric relaxation responses at 20 wt % loading and a reduced percolation threshold realized conductivities of 1.19 × 10–4 S cm–1 at 10 wt %, compared to 2.62 × 10–15 S cm–1 for pristine CB/PP nanocomposites at the same filler loading. In addition, thermal properties signify an increase in the number of nucleation sites by the raised degree of crystallinity as well as increased melting and crystallization temperatures.
Co-reporter:Tharindi D. Panduwawala, Laia Josa-Culleré, Ilya Kuprov, Barbara Odell, Mark G. Moloney, and Timothy D. W. Claridge
The Journal of Organic Chemistry 2016 Volume 81(Issue 10) pp:4142-4148
Publication Date(Web):May 5, 2016
DOI:10.1021/acs.joc.6b00458
Anomalous cross-peaks observed in the NOESY spectra of 2,4-disubstituted thiazolidines and oxazolidines that cannot be attributed to classical dipolar NOE or chemical exchange peaks have been investigated experimentally and computationally and have been shown to arise from scalar cross-relaxation of the first kind. This process is stimulated by the relatively slow modulation of scalar couplings and, for the systems studied, arises from slow on–off proton exchange of the amino nitrogen, a process influenced by solution temperature, acidity, and concentration. The mechanism is likely to be significant for many systems in which proton exchange occurs on the millisecond time scale, and misinterpretation of these cross-peaks may lead to erroneous conclusions should their true origins not be recognized.
Co-reporter:Lawrence Harris, Martin Gilpin, Amber L. Thompson, Andrew R. Cowley and Mark G. Moloney
Organic & Biomolecular Chemistry 2015 vol. 13(Issue 23) pp:6522-6550
Publication Date(Web):05 May 2015
DOI:10.1039/C5OB00648A
The uncatalysed cycloaddition of substituted diaryldiazo compounds onto bicyclic unsaturated lactams derived from pyroglutamic acid efficiently leads to highly functionalised azatricyclononanes. The products are readily elaborated to deprotected pyroglutamate derivatives, providing rapid access to conformationally constrained amino acids and their analogues. Preliminary assessment of antibacterial activity against one Gram positive and one Gram negative organism indicated high levels of efficacy in some cases.
Co-reporter:Jinnan Zhang, Zhanfeng Cui, Robert Field, Mark G. Moloney, Stephen Rimmer, Hua Ye
European Polymer Journal 2015 Volume 67() pp:346-364
Publication Date(Web):June 2015
DOI:10.1016/j.eurpolymj.2015.04.013
•Microcarrier cell culture systems are useful for cell culture amplification.•Surface PNIPAAm releases cells by temperature adjustment.•This review presents methods to prepare PNIPAAm microcarriers.•The efficiency of methods is compared.Microcarrier cell culture systems provide an attractive alternative to the conventional monolayer cell culture for cell amplification, due to their high surface area-to-volume ratio. Unlike enzymatic methods for removing cells from microcarriers after cell culture, which can lead to irreversible damage of the cells, microcarriers which release cells by temperature adjustment have been developed. This was achieved by grafting a temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), on the microcarrier surface. This review comprehensively presents various methods to prepare such thermo-responsive microcarriers based on PNIPAAm. These methods include the grafting-to technique, grafting-from technique, grafting-through technique, along with methods leading to PNIPAAm hydrogel beads, seeded polymerization, and non-covalent adsorption. The methods for controlling PNIPAAm grafting density, molecular weight and molecular architecture are also outlined. Further, the efficiency of cell attachment, proliferation and thermally-induced detachment of such thermo-responsive microcarriers is introduced and compared.
Co-reporter:Song Wei Benjamin Tan, Christina L. L. Chai, Mark G. Moloney, and Amber L. Thompson
The Journal of Organic Chemistry 2015 Volume 80(Issue 5) pp:2661-2675
Publication Date(Web):February 3, 2015
DOI:10.1021/jo502810b
Epoxypyrrolidinones are available by epoxidation of carboxamide-activated bicyclic lactam substrates derived from pyroglutamate using aqueous hydrogen peroxide and tertiary amine catalysis. In the case of an activating Weinreb carboxamide, further chemoselective elaboration leads to the efficient formation of libraries of epoxyketones. Deprotection may be achieved under acidic conditions to give epoxypyroglutaminols, although the ease of this process can be ameliorated by the presence of internal hydrogen bonding. Bioassay against S. aureus and E. coli indicated that some compounds exhibit antibacterial activity. These libraries may be considered to be structural mimics of the natural products pramanicin and epolactaene. More generally, this outcome suggests that interrogation of bioactive natural products is likely to permit the identification of “privileged” structural scaffolds, providing frameworks suitable for optimization in a short series of chemical steps that may accelerate the discovery of new antibiotic chemotypes. Further optimization of such systems may permit the rapid identification of novel systems suitable for antibacterial drug development.
Co-reporter:Song Wei Benjamin Tan, Christina L. L. Chai and Mark G. Moloney
Organic & Biomolecular Chemistry 2014 vol. 12(Issue 11) pp:1711-1716
Publication Date(Web):04 Feb 2014
DOI:10.1039/C4OB00095A
An efficient approach for the introduction of 3-acyl side chain groups onto a core tetramate system, which are suitable for further manipulation by nucleophilic displacement or Horner–Wadsworth–Emmons coupling, provides access to a diverse library of substituted tetramates related to two distinct classes of natural products, equisetin and pramanicin. Assessment against S. aureus and E. coli indicated that some compounds exhibit significant antibacterial activity, providing unusual leads for further optimisation in the drug discovery process.
Co-reporter:Elizabeth A. Heaviside, Mark G. Moloney and Amber L. Thompson
RSC Advances 2014 vol. 4(Issue 31) pp:16233-16249
Publication Date(Web):21 Mar 2014
DOI:10.1039/C4RA01967A
Intramolecular aldol reactions on oxazolidine templates derived from threonine may be used to generate libraries of densely functionalised pyroglutamates with a high level of diastereoselectivity; the oxazolidine precursors themselves are suitable for further direct manipulation by side chain alkylation, permitting rapid access to cyclised products with several points of chemical diversity. Although these systems may be considered to be structural mimics of the functionalised pyroglutamate portion of oxazolomycin, little antibacterial activity against S. aureus and E. coli was found. These systems may additionally have application as three-dimensional fragments for drug discovery and development.
Co-reporter:Yong-Chul Jeong, Muhammad Anwar, Mark G. Moloney
Bioorganic & Medicinal Chemistry Letters 2014 Volume 24(Issue 8) pp:1901-1906
Publication Date(Web):15 April 2014
DOI:10.1016/j.bmcl.2014.03.013
Co-reporter:Claire L. Bagwell;David M. L. Leonard;Jon-Paul Griffiths;Nick J. Stratton;Daniel P. Travers
Macromolecular Reaction Engineering 2014 Volume 8( Issue 2) pp:170-180
Publication Date(Web):
DOI:10.1002/mren.201200088
Diarylcarbenes have been shown to be suitable for the surface modification of a diverse range of polymers, including low surface energy materials, and this allows the modification of surface macroscopic effects, exemplified by changes in wetting behaviour, pH sensing, and bactericidal activity.
Co-reporter:Dr. Yong-Chul Jeong;Dr. Zsolt Bikadi;Dr. Eszter Hazai; Mark G. Moloney
ChemMedChem 2014 Volume 9( Issue 8) pp:1826-1837
Publication Date(Web):
DOI:10.1002/cmdc.201402093
Abstract
Inspired by the core fragment of antibacterial natural products such as streptolydigin, 3-acyltetramic acids and 3-acylpiperidine-2,4-diones have been synthesised from the core heterocycle by direct acylation with the substituted carboxylic acids using a strategy which permits ready access to a structurally diverse compound library. The antibacterial activity of these systems has been established against a panel of Gram-positive and Gram-negative bacteria, with activity mostly against the former, which in some cases is very potent. Data consistent with modes of action against undecaprenylpyrophosphate synthase (UPPS) and/or RNA polymerase (RNAP) for a small subset of the library has been obtained. The most active compounds have been shown to exhibit binding at known binding sites of streptolydigin and myxopyronin at UPPS and RNAP. These systems offer potential for their antibacterial activity, and further demonstrate the use of natural products as biologically validated starting points for drug discovery.
Co-reporter:Yong-Chul Jeong, Muhammad Anwar, Zsolt Bikadi, Eszter Hazai and Mark G. Moloney
Chemical Science 2013 vol. 4(Issue 3) pp:1008-1015
Publication Date(Web):28 Nov 2012
DOI:10.1039/C2SC21713A
The application of natural product inspired synthesis has identified novel antibacterial tetramic acids which exhibit wide ranging antibacterial activity, and which provide potential lead structures for antibacterial drug discovery. Their phenotypic activity appears to correlate with action at two enzymes, UPPS and RNAP, which operate in independent metabolic pathways. SAR maps and identification of their relevant binding sites by molecular modelling has been achieved, and characterisation of the most active compounds suggests that these systems offer potential for topical antibiotics but that for oral and injectable use further optimisation is required.
Co-reporter:Muhammad Anwar
Chemical Biology & Drug Design 2013 Volume 81( Issue 5) pp:645-649
Publication Date(Web):
DOI:10.1111/cbdd.12110
Chemoselective Dieckmann cyclization reactions may be used on oxazolidine and thiazolidine templates derived from various aldehydes to access bicyclic tetramates, which have potential as templates for chemical library construction. Bioassay against Staphylococcus aureus and Escherichia coli showed that these systems have little or no intrinsic antibacterial bioactivity.
Co-reporter:Nandkishkor Chandan, Mark G. Moloney
Tetrahedron Letters 2013 Volume 54(Issue 15) pp:1987-1990
Publication Date(Web):10 April 2013
DOI:10.1016/j.tetlet.2013.01.130
2,2,5-Trisubstituted pyrrolidines of relevance to the core of kaitocephalin are readily available by an oxime ring closure using substrates derived from aspartic acid.
Co-reporter:Apichat Aphaiwong, Mark G. Moloney and Martin Christlieb
Journal of Materials Chemistry A 2012 vol. 22(Issue 47) pp:24627-24636
Publication Date(Web):21 Sep 2012
DOI:10.1039/C2JM34942F
Functionalised diarylcarbenes can be used as anchoring agents for the introduction of metal chelating ligands onto the surface of a polystyrene substrate, rapidly creating a library of chelating polymers from a common precursor; although exemplified for polystyrene, the method is potentially applicable to a wide range of polymer substrates. Evaluation of the binding of zinc complexes followed by ligand transfer and release of copper complexes indicated that a pyridyl modified system offered considerable potential for application in the rapid generation of ligand systems of relevance for radiopharmaceutical synthesis.
Co-reporter:Plamen Angelov, Yui Kwan Sonia Chau, Paul J. Fryer, Mark G. Moloney, Amber L. Thompson and Paul C. Trippier
Organic & Biomolecular Chemistry 2012 vol. 10(Issue 17) pp:3472-3485
Publication Date(Web):29 Feb 2012
DOI:10.1039/C2OB00042C
Biomimetic intramolecular aldol reactions on oxazolidine templates derived from serine may be used to generate densely functionalised pyroglutamates, which are simpler mimics of the right hand side of oxazolomycin. Some of the compounds from this sequence exhibit in vivo activity against S. aureus and E. coli, suggesting that pyroglutamate scaffolds may be useful templates for the development of novel antibacterials, and cheminformatic analysis has been used to provide some structure–activity data.
Co-reporter:Nandkishor Chandan, Amber L. Thompson and Mark G. Moloney
Organic & Biomolecular Chemistry 2012 vol. 10(Issue 39) pp:7863-7868
Publication Date(Web):2012/08/15
DOI:10.1039/C2OB26423D
Substituted pyrrolines are available by ring closure initiated by direct nucleophilic attack of stabilized enolates at the nitrogen of oximes activated with a leaving group, in a process which effectively out-competes the more usual Beckmann rearrangement. Subsequent reduction provides diastereoselective access to the corresponding pyrrolidines. This provides a rapid route to saturated heterocyclic systems from readily available precursors.
Co-reporter:Cleo Choong, J. S. Foord, Jon-Paul Griffiths, Emily M. Parker, Luo Baiwen, Meghali Bora and Mark G. Moloney
New Journal of Chemistry 2012 vol. 36(Issue 5) pp:1187-1200
Publication Date(Web):02 Mar 2012
DOI:10.1039/C2NJ00002D
Derivatisation of polystyrene by carbene insertions followed by diazonium coupling permits the introduction of diverse chemical functionality, providing access to materials with similar bulk properties, but in which surface chemical characteristics are systematically varied across a range of surface polarity, hydration and non-bonding interaction behaviour. Protein binding experiments with bovine serum albumin demonstrate that protein adhesion is dependent upon the identity of the surface chemical group, with tert-butyl, hexyl, dimethylamino, amino, and carboxyl modified systems all exhibiting higher levels of binding, while glycol, hydroxyl, and phosphonate give similar or lower levels of binding, relative to the control. This behaviour has been shown to be time dependent, and an approximate trend of protein binding with cheminformatic descriptors %PSA and contact angle was observed.
Co-reporter:Yong-Chul Jeong, Muhammad Anwar, Tuan Minh Nguyen, Benjamin Song Wei Tan, Christina Li Lin Chai and Mark G. Moloney
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 19) pp:6663-6669
Publication Date(Web):20 Jun 2011
DOI:10.1039/C1OB05816A
An efficient strategy for the control of the chemoselectivity in Dieckmann ring closures leading to tetramic acids derived from serine and α-methyl serine is reported, and this provides pathways to diversely substituted systems from a common starting material.
Co-reporter:Chloe A. Holloway;Christopher J. Matthews;Yong-Chul Jeong;Christine F. Roberts ;Muhammad Yaqoob
Chemical Biology & Drug Design 2011 Volume 78( Issue 2) pp:229-235
Publication Date(Web):
DOI:10.1111/j.1747-0285.2011.01133.x
Modification of the ring nucleus of tetramic acids derived from serine gives chiral heterocyclic libraries that exhibit antibacterial activity, and correlation with various physicochemical parameters indicates that chiral tetramic acids may provide a potentially valuable non-aromatic skeleton for fragment-based drug discovery.
Co-reporter:Philip J. Davis, Lawrence Harris, Aman Karim, Amber L. Thompson, Martin Gilpin, Mark G. Moloney, Matthew J. Pound, Claire Thompson
Tetrahedron Letters 2011 Volume 52(Issue 14) pp:1553-1556
Publication Date(Web):6 April 2011
DOI:10.1016/j.tetlet.2011.01.116
The synthesis of several substituted diaryldiazomethanes and diazofluorenes, and an assessment of their structure, reactivity and stability, is reported.
Co-reporter:Yong-Chul Jeong and Mark G. Moloney
The Journal of Organic Chemistry 2011 Volume 76(Issue 5) pp:1342-1354
Publication Date(Web):January 20, 2011
DOI:10.1021/jo102304y
The synthesis of 3-acyltetramic acids, the substructure of bioactive natural products, via O-acylation of tetramic acids with carboxylic acids followed by acyl migration, has been investigated. This acylation sequence is mediated by N,N′-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) and is very sensitive to the nature of the nitrogen substituent (R1), the nature of the carboxylic acid (R2CO2H), and the amount of DMAP. Acylation of N-acyl tetramic acids with an alkyl carboxylic acid using 1.3 equiv of DMAP (with 1.1 equiv of DCC) unexpectedly gave the 3-acyltetramic acid directly as a result of acyl migration induced by excess amounts of DMAP. On the other hand, N-unsubstituted, N-alkyl, and N-acyl tetramic acids with alkyl and aromatic carboxylic acids gave the O-acyl tetramic acids by using only 0.1 equiv of DMAP (with 1.1 equiv of DCC); these could be further rearranged to the acyl product by treatment with excess DMAP. The tautomeric equilibrium of these 3-acyltetramic acids in solution was found to strongly depend on the nitrogen substituent group (R1) rather than the 3-acyl group.
Co-reporter:Xin-Gui Li, Hu Li, Mei-Rong Huang, and Mark G. Moloney
The Journal of Physical Chemistry C 2011 Volume 115(Issue 19) pp:9486-9497
Publication Date(Web):April 26, 2011
DOI:10.1021/jp201967n
Intrinsically self-stabilized nanofibril bundles of poly(1-aminoanthraquinone) (PAQ) were facilely synthesized by the chemical oxidative polymerization of 1-aminoanthraquinone. Critical polymerization parameters such as the monomer concentration, medium, oxidant species, temperature, and time were studied to significantly optimize the synthesis, size, properties, and multifunctionality of the resulting nanofibrils by IR, UV–vis, and fluorescence spectroscopy, X-ray diffraction, SEM, TEM, DSC, and thermogravimetry. It is found that the polymerization of 1-aminoanthraquinone with (NH4)2S2O8 as an oxidant in HClO4/acetonitrile without external stabilizer simply affords finer PAQ nanofibrils with an optimal combination of diameter of ca. 15 nm, a length of ∼6 μm, a higher preparation yield, a purer composition, a higher conductivity, and higher melting and decomposition temperatures than that with CrO3 and H2O2/Fe2+. Furthermore, the polymer nanofibrils exhibit high self-stability, powerful redispersibility, and a clean surface because of the complete avoidance of contamination from an external stabilizer. PAQ exhibits remarkably good solubility in polar solvents, colorful solvatochromism, widely controllable conductivity moving across 10 orders of magnitude from 10–9 to 50 S/cm, fluorescence, lead-ion adsorbability, high thermostability in air, and a very high carbon yield in nitrogen at 1000 °C. In particular, the nanoeffect of the PAQ nanofibrils with a large specific surface area and aspect ratio further enhances their fluorescence, lead-ion adsorbability, and nanocomposite ability of facilely forming a unique nanonetwork. PAQ would be useful as advanced materials including fluorescent emitters, sorbents of toxic metallic ions, cost-effective carbon foam precursors, and conducting nanocomposites with low percolation thresholds.
Co-reporter:Claire L. Bagwell, Mark G. Moloney, Muhammad Yaqoob
Bioorganic & Medicinal Chemistry Letters 2010 Volume 20(Issue 7) pp:2090-2094
Publication Date(Web):1 April 2010
DOI:10.1016/j.bmcl.2010.02.066
Conjugation of amide and lactam subunits by a ‘Click’ type approach provides access to structural mimics of the oxazolomycin series of natural products, some of which exhibit antibacterial activity.Conjugation of lactams and amides by Click homologation gives bioactive mimics of oxazolomycin.
Co-reporter:Xin-Gui Li ;You-Wei Liu;Mei-Rong Huang ;Sai Peng;Ling-Zhi Gong;MarkG. Moloney Dr.
Chemistry - A European Journal 2010 Volume 16( Issue 16) pp:4803-4813
Publication Date(Web):
DOI:10.1002/chem.200902621
Abstract
A wholly aromatic polypyrene was synthesized by direct chemical oxidative polymerization of pyrene with ferric chloride as oxidant in hexane/nitromethane. Successful synthesis of polypyrene was thoroughly confirmed by IR, UV/Vis, 1D 1H NMR, 2D 1H–1H COSY, 2D 1H–13C HSQC, MALDI-TOF MS, elemental analysis, and X-ray diffraction methods. The results indicated that the polypyrene was formed mainly through dehydro coupling between 2- or 1- and 2′- or 1′-positions on pyrene rings having a degree of polymerization of around 24. The polypyrene was purified and then separated into THF-soluble (ca. 10 %) and THF-insoluble (ca. 90 %) fractions. Compared with insulating pyrene monomer, the polypyrene is a controllably conducting polymer that has low conductivity of 3.4×10−8 S cm−1 in its virgin state, moderate conductivity of 2.28×10−4 S cm−1 upon iodine doping, but much higher conductivity of up to 81.2 S cm−1 after the insoluble polypyrene was heated up to 1300 °C in nitrogen with a high char yield of 70.6 %. In particular, the soluble polypyrene demonstrates much stronger visible color fluorescence and much lower toxicity than pyrene. The soluble polypyrene would be advantageous for detecting Fe3+ with almost no interference of other metal ions. The soluble and insoluble polypyrene fractions have potential applications as intrinsically luminescent and highly conducting carbon materials, respectively.
Co-reporter:Muhammad Anwar, Andrew R. Cowley, Mark G. Moloney
Tetrahedron: Asymmetry 2010 Volume 21(13–14) pp:1758-1770
Publication Date(Web):14 July 2010
DOI:10.1016/j.tetasy.2010.04.064
Co-reporter:Jon-Paul Griffiths, Bushra Maliha, Mark G. Moloney and Amber L. Thompson, Ishtiaq Hussain
Langmuir 2010 Volume 26(Issue 17) pp:14142-14153
Publication Date(Web):July 30, 2010
DOI:10.1021/la1023482
Functionalized diarylcarbenes are excellent reactive intermediates suitable for the direct surface modification of organic polymers, and these may be used to introduce urea and thiourea functions onto polystyrene at loading levels of up to 2.3 × 1013 molecules/cm2. These functions are capable of the reversible binding and release of peroxide at loading levels of up to 0.6 mmol/g and give polymers that display biocidal activity against a spectrum of gram-positive and gram-negative bacteria.
Co-reporter:Xin-Gui Li, Zhen-Zhong Hou, Mei-Rong Huang and Mark G. Moloney
The Journal of Physical Chemistry C 2009 Volume 113(Issue 52) pp:21586-21595
Publication Date(Web):November 25, 2009
DOI:10.1021/jp9081504
Self-stabilized copolymer nanoparticles are easily and productively synthesized by a chemical oxidative polymerization of pyrrole (Py) and 2-hydroxy-5-sulfonic aniline (HS) in 1 M HCl without any external template. UV−vis, IR, 1D 1H NMR, 2D 1H−1H COSY NMR, and 2D 1H−13C HSQC NMR all indicate that a real copolymerization occurs between HS and Py comonomers and Py units construct the main position of the copolymer. On the basis of the elemental analysis, the reactivity ratios of HS and Py comonomers are calculated to be 0.043 and 1.14, respectively. The polymerization yield, size, morphology, and electrical conductivity of the copolymer particles can significantly be optimized by the comonomer ratio, polymerization temperature, and ammonium persulfate oxidant/comonomer ratio. The copolymer particles always keep narrow size distribution with a small polydispersity index (PDI) of 1.05−1.08. HS/Py(50/50) copolymer nanoparticles synthesized at 0 °C are found to generally have irregular granular morphology with the smallest diameter of 35−60 nm and the lowest PDI of 1.05 by laser particle-size analyzer, FE-SEM, and TEM. The mechanisms of the formation and intrinsic self-stabilization of the nanoparticles are proposed based on the powerful static repulsion from negatively charged sulfonic and hydroxyl groups on the nanoparticles. Through simple dedoping and redoping procedures, the copolymer particles exhibit a widely adjustable conductivity from 10−9 to 1.12 S cm−1. These copolymer nanoparticles show high conductivity, good self-stability, and powerful redispersibility in water and organic media. Nanocomposite films of the copolymer nanoparticles in polyvinylalcohol possess a low percolation threshold down to 0.09 wt % as well as retain 80−95% transparency and 102−108 times the conductivity of the pure polyvinylalcohol film in the nanoparticle loading from 0.09 to 3 wt %.
Co-reporter:Ian F. Cottrell, Mark G. Moloney, Kirsty Smithies
Tetrahedron Letters 2009 50(10) pp: 1097-1099
Publication Date(Web):
DOI:10.1016/j.tetlet.2008.12.071
Co-reporter:Ian F. Cottrell, Andrew R. Cowley, Laura J. Croft, Lauren Hymns, Mark G. Moloney, Ewan J. Nettleton, H. Kirsty Smithies, Amber L. Thompson
Tetrahedron 2009 65(12) pp: 2537-2550
Publication Date(Web):
DOI:10.1016/j.tet.2009.01.042
Co-reporter:Lawrence Harris, Martin Gilpin, Amber L. Thompson, Andrew R. Cowley, Mark G. Moloney
Tetrahedron: Asymmetry 2009 Volume 20(6–8) pp:726-729
Publication Date(Web):7 May 2009
DOI:10.1016/j.tetasy.2009.02.037
Co-reporter:Cleo Choong, Jon-Paul Griffiths, Mark G. Moloney, James Triffitt, Diane Swallow
Reactive and Functional Polymers 2009 69(2) pp: 77-85
Publication Date(Web):February 2009
DOI:10.1016/j.reactfunctpolym.2008.11.003
Co-reporter:Amjid Iqbal, Mark G. Moloney, Hamid Latif Siddiqui, Amber L. Thompson
Tetrahedron Letters 2009 50(31) pp: 4523-4525
Publication Date(Web):
DOI:10.1016/j.tetlet.2009.05.086
Co-reporter:Karim M. Awenat, Philip J. Davis, Mark G. Moloney and Warren Ebenezer
Chemical Communications 2005 (Issue 8) pp:990-992
Publication Date(Web):12 Jan 2005
DOI:10.1039/B414856H
A method for the application of carbenes as reactive intermediates for surface modification of polymeric substrates has been developed; the efficacy of the process has been demonstrated by irreversible dyeing of polystyrene, polythene, nylon, silica, and controlled pore glass, and to a limited extent, polytetrafluoroethylene.
Co-reporter:Jonathan E. H. Buston, Tim D. W. Claridge, Stephen J. Heyes, Michael A. Leech, Mark G. Moloney, Keith Prout and Maya Stevenson
Dalton Transactions 2005 (Issue 19) pp:3195-3203
Publication Date(Web):18 Aug 2005
DOI:10.1039/B506366C
A 1 : 1 crystalline complex of lead(IV) tetraacetate and pyridine (LTA–py) has been prepared. The single-crystal X-ray structure, at 296 and 150 K, establishes the presence of a relatively short Pb–N bond (2.307 Å) within an intriguing seven-coordinate lead inner sphere consisting of the pyridine ligand and two bidentate and two monodentate acetate ligands. The pyridine occupies a surprising amount of the available coordination space and has induced a dramatic change in coordination compared to the four chelating acetate ligands found in lead tetraacetate (LTA). Thermal measurements (TGA/DSC) indicate the de-coordination of pyridine and its loss from the solid between 360 and 380 K. 207Pb CP/MAS NMR spectroscopy also demonstrates the existence of the Pb–N bond through observation of 1J(207Pb,14N)
= 63 Hz and a 207Pb–14N dipolar coupling constant, of 149 Hz. The solid-state 207Pb NMR parameters are used to give insight into the coordination environment of Pb(IV) in LTA–py. In solution, ligand exchange is rapid on chemical shift and J-coupling time scales. A 207Pb NMR study of the titration of an LTA solution by pyridine yields a stability constant for LTA–py of K = 1.5 M−1 and predicts it to have a 207Pb NMR chemical shift essentially identical to that observed by CP/MAS NMR in the solid state. This correlation between the solid state and solution indicates that the seven-coordinate LTA–py structure found in the crystalline state does persist in solution, and this could further explain why the addition of pyridine has such profound effects on lead(IV) carboxylate-mediated organic reactions. Simulations of exchange-broadened line shapes of 13C CP/MAS NMR spectra in the temperature regime above 280 K indicate local motion of the pyridine rings in the form of 180° jumps (activation energy 72.5 kJ mol−1); these are first such ring flips reported for a coordinated pyridine ligand.
Co-reporter:Emilie L. Bentz, Rajesh Goswami, Mark G. Moloney and Susan M. Westaway
Organic & Biomolecular Chemistry 2005 vol. 3(Issue 15) pp:2872-2882
Publication Date(Web):01 Jul 2005
DOI:10.1039/B503994K
Bicyclic lactams derived from pyroglutamic acid provide a useful scaffold for synthesis of conformationally restricted analogues of lysine, ornithine and glutamine, as well as an Ala–Ala dipeptide analogue. Amino alcohol and carboxylic acid derivatives are accessible from a common intermediate. In this strategy, the bicyclic lactam system not only controls, but also facilitates the determination of the stereochemistry of the synthetic intermediates.
Co-reporter:Andrew G. Brewster, Simon Broady, Catherine E. Davies (née Mills), Thomas D. Heightman, Stephen A. Hermitage, Mark Hughes, Mark G. Moloney and Gordon Woods
Organic & Biomolecular Chemistry 2004 vol. 2(Issue 7) pp:1031-1043
Publication Date(Web):03 Mar 2004
DOI:10.1039/B316037H
The synthesis and alkylation of [4.3.0]-bicyclic lactams, derived from 6-oxopipecolic acid, have been investigated. Alkylation can proceed with predominantly exo-diastereoselectivity, but the efficiency of this process depends on the substitution at the hemiaminal ether system. These products can be readily deprotected to give substituted hydroxymethyl lactams in good yield.
Co-reporter:Ian F. Cottrell, Philip J. Davis, Mark G. Moloney
Tetrahedron: Asymmetry 2004 Volume 15(Issue 8) pp:1239-1242
Publication Date(Web):19 April 2004
DOI:10.1016/j.tetasy.2004.03.008
Stereoselective syntheses of the epoxy and diol derivatives of a bicyclic lactam derived from pyroglutamic acid are reported, and their reactivity is discussed.Graphic6,7-Epoxy-7-ethoxycarbonyl-8-oxo-2-phenyl-1-aza-3-oxa-bicyclo[3.3.0]octaneC15H16NO5[α]D22=+20.9 (c=1, CHCl3)Source of chirality: (S)-pyroglutamic acidAbsolute configuration: (2R,5R,6R,7R)3,4-Epoxy-4-ethoxycarbonyl-2-hydroxymethyl-5-oxo-pyrrolidineC8H12NO5[α]D22=+0.3 (c=0.075, CHCl3)Source of chirality: (S)-pyroglutamic acidAbsolute configuration: (2R,3R,4R)7-Ethoxycarbonyl-8-oxo-2-phenyl-6,7-dihydroxy-1-aza-3-oxa-bicyclo[3.3.0]octaneC15H18NO6[α]D22=+127 (c=1, CHCl3)Source of chirality: (S)-pyroglutamic acidAbsolute configuration: (2R,5R,6R,7R)6-Acetoxy-7-ethoxycarbonyl-8-oxo-2-phenyl-7-hydroxy-1-aza-3-oxa-bicyclo[3.3.0]octaneC17H20NO7[α]D22=+2.9 (c=0.025, CHCl3)Source of chirality: (S)-pyroglutamic acidAbsolute configuration: (2R,5R,6R,7R)
Co-reporter:Philip W. H. Chan, Ian F. Cottrell and Mark G. Moloney
Organic & Biomolecular Chemistry 2001 (Issue 22) pp:3007-3012
Publication Date(Web):25 Oct 2001
DOI:10.1039/B106783B
The electrophilic amination of a β-aminolactam, itself derived from the conjugate addition of O,N-dibenzylhydroxylamine to a highly activated α,β-unsaturated bicyclic lactam, provides direct access to conformationally constrained diamines. Sequential deprotection allows the synthesis of 3,4-diaminopyroglutaminols.
Co-reporter:Philip W. H. Chan, Ian F. Cottrell and Mark G. Moloney
Organic & Biomolecular Chemistry 2001 (Issue 22) pp:2997-3006
Publication Date(Web):25 Oct 2001
DOI:10.1039/B106782F
The conjugate addition of activated nitrogen nucleophiles, such as hydroxylamine and hydrazine derivatives, to α,β-unsaturated bicyclic lactam 1a gave the corresponding β-amino products 9a–g in good yield and excellent diastereoselectivity. These products can be manipulated to afford enantiopure β-aminopyrrolidinones of potential application as conformationally-constrained, substituted glutamate templates of well-defined stereochemistry.
Co-reporter:Tim D. W. Claridge;Jonathan E. H. Buston;Stephen J. Heyes;Jeremy L. Bretherton;Maya Stevenson
Magnetic Resonance in Chemistry 2001 Volume 39(Issue 2) pp:68-76
Publication Date(Web):12 JAN 2001
DOI:10.1002/1097-458X(200102)39:2<68::AID-MRC802>3.0.CO;2-C
207Pb NMR spectroscopy was used to investigate 20 lead(IV) tetracarboxylates both in solution and in the solid state by cross-polarization magic angle spinning (CP/MAS) NMR. There is generally good correlation between isotropic chemical shifts in the solid state and those in solution. Multiple CP/MAS NMR isotropic resonances are observed for three of the compounds and are interpreted in terms of multiple molecules in the crystallographic asymmetric unit. From an analysis of the range of, and trends in, the NMR chemical shifts, circumstantial evidence is presented for augmentary coordination by Lewis basic ortho-aromatic substituents of the carboxylate groups. The 207Pb chemical shift anisotropy (CSA) parameters were extracted from analysis of the spinning sideband manifolds of the CP/MAS spectra. The CSA spreads are small in comparison with others reported for 207Pb, and all have positive skew, in contrast to the typical case for lead(II) compounds. Thirteen of the 20 CSA analyses performed show effectively axial CSA tensors. A simple shielding model which rationalizes this typical CSA pattern is presented, based on an analysis of geometric information derived from the two known single-crystal x-ray structures of lead(IV) carboxylates. Copyright © 2001 John Wiley & Sons, Ltd.
Co-reporter:Jonathan H. Bailey, Andrew T. J. Byfield, Philip J. Davis, Alison C. Foster, Michael Leech, Mark G. Moloney, Matthias Müller and C. Keith Prout
Organic & Biomolecular Chemistry 2000 (Issue 12) pp:1977-1982
Publication Date(Web):30 May 2000
DOI:10.1039/B000432O
The diastereoselectivity in the alkylation of the enolates of bicyclic lactams 2 derived from pyroglutaminol 1a has been found to depend upon the nature of the hemiaminal ether protecting group. Although exo-alkylation has been widely reported for 2a,b,e, endo-alkylation is favoured for 2d. It is postulated that this is a result of the opening of the bicyclic structure of the enolate derived from 2d, and the consequent stereoelectronic facilitation of endo-facial attack.
Co-reporter:James Dyer, Amanda King, Steve Keeling and Mark G. Moloney
Organic & Biomolecular Chemistry 2000 (Issue 16) pp:2793-2804
Publication Date(Web):21 Jul 2000
DOI:10.1039/B002001J
Novel conformationally constrained glutamate analogues are readily available from (S)-pyroglutamic acid using a bicyclic lactam as a synthetic template; diastereocontrolled modification of the pyrrolidine ring using a sequential conjugate addition–substitution strategy permits access to several kainoid analogues in a versatile strategy. The pyrrolidinone ring conformation appears to be controllable by the nature of remote substituents on the heterocyclic ring.
Co-reporter:Jonathan H. Bailey, David T. Cherry, James Dyer, Mark G. Moloney, Mark J. Bamford, Steve Keeling and R. Brian Lamont
Organic & Biomolecular Chemistry 2000 (Issue 16) pp:2783-2792
Publication Date(Web):21 Jul 2000
DOI:10.1039/B001999M
Novel conformationally constrained pyroglutaminols and pyroglutamates are readily available using an α,β-unsaturated bicyclic lactam as a template for diastereocontrolled enolate additions in the key step; zinc enolates are particularly effective in this regard. The bicyclic ring system both controls and permits the determination of ring stereochemistry. The utility of this methodology is demonstrated by a formal total synthesis of the NMDA receptor agonist, CPAA 11.
Co-reporter:Jonathan E. H. Buston;Tim D. W. Claridge;Richard G. Compton
Magnetic Resonance in Chemistry 1998 Volume 36(Issue 2) pp:140-144
Publication Date(Web):4 DEC 1998
DOI:10.1002/(SICI)1097-458X(199802)36:2<140::AID-OMR245>3.0.CO;2-7
207Pb NMR spectroscopy was used to investigate the nature of aryllead(IV) tricarboxylate species in solution. The 207Pb chemical shifts of p-Br- and p-MeO-aryllead tricarboxylates were found to depend on both electronic (as measured by the pKa of the parent acid) and steric effects of the neighbouring carboxylic acid ligands. © 1998 John Wiley & Sons, Ltd.
Co-reporter:Mark G. Moloney
Trends in Pharmacological Sciences (August 2016) Volume 37(Issue 8) pp:689-701
Publication Date(Web):1 August 2016
DOI:10.1016/j.tips.2016.05.001
Natural products have historically been of crucial importance in the identification and development of antibacterial agents. Interest in these systems has waned in recent years, but the rapid emergence of resistant bacterial strains has forced their re-evaluation as a route to identify novel chemical skeletons with antibacterial activity for elaboration in drug development. This overview examines the current situation, highlights new natural product systems which have been found, together with re-examination of some old ones, and new technologies for their identification. While natural products certainly have the potential to re-emerge as a key start-point in antibacterial drug discovery, reports of new or reinvestigated structures need to be supported with sufficient quality chemical (solubility, stability), biochemical (including toxicity in particular, along with target information) and microbiological [minimum inhibitory concentration (MIC) and resistance frequency] validation data to assist in the identification of promising hit structures and to avoid wasted effort from trawling over already cultivated territory. This is particularly important in a resource-limited research environment.
Co-reporter:Apichat Aphaiwong, Mark G. Moloney and Martin Christlieb
Journal of Materials Chemistry A 2012 - vol. 22(Issue 47) pp:NaN24636-24636
Publication Date(Web):2012/09/21
DOI:10.1039/C2JM34942F
Functionalised diarylcarbenes can be used as anchoring agents for the introduction of metal chelating ligands onto the surface of a polystyrene substrate, rapidly creating a library of chelating polymers from a common precursor; although exemplified for polystyrene, the method is potentially applicable to a wide range of polymer substrates. Evaluation of the binding of zinc complexes followed by ligand transfer and release of copper complexes indicated that a pyridyl modified system offered considerable potential for application in the rapid generation of ligand systems of relevance for radiopharmaceutical synthesis.
Co-reporter:Yong-Chul Jeong, Muhammad Anwar, Zsolt Bikadi, Eszter Hazai and Mark G. Moloney
Chemical Science (2010-Present) 2013 - vol. 4(Issue 3) pp:NaN1015-1015
Publication Date(Web):2012/11/28
DOI:10.1039/C2SC21713A
The application of natural product inspired synthesis has identified novel antibacterial tetramic acids which exhibit wide ranging antibacterial activity, and which provide potential lead structures for antibacterial drug discovery. Their phenotypic activity appears to correlate with action at two enzymes, UPPS and RNAP, which operate in independent metabolic pathways. SAR maps and identification of their relevant binding sites by molecular modelling has been achieved, and characterisation of the most active compounds suggests that these systems offer potential for topical antibiotics but that for oral and injectable use further optimisation is required.
Co-reporter:Plamen Angelov, Yui Kwan Sonia Chau, Paul J. Fryer, Mark G. Moloney, Amber L. Thompson and Paul C. Trippier
Organic & Biomolecular Chemistry 2012 - vol. 10(Issue 17) pp:NaN3485-3485
Publication Date(Web):2012/02/29
DOI:10.1039/C2OB00042C
Biomimetic intramolecular aldol reactions on oxazolidine templates derived from serine may be used to generate densely functionalised pyroglutamates, which are simpler mimics of the right hand side of oxazolomycin. Some of the compounds from this sequence exhibit in vivo activity against S. aureus and E. coli, suggesting that pyroglutamate scaffolds may be useful templates for the development of novel antibacterials, and cheminformatic analysis has been used to provide some structure–activity data.
Co-reporter:Tharindi D. Panduwawala, Sarosh Iqbal, Rémi Tirfoin and Mark G. Moloney
Organic & Biomolecular Chemistry 2016 - vol. 14(Issue 19) pp:NaN4478-4478
Publication Date(Web):2016/04/12
DOI:10.1039/C6OB00557H
Chemoselective Dieckmann cyclisation reactions on N-malonyl thiazolidine templates derived from cysteine and pivaldehyde or aromatic aldehydes may be used to access bicyclic tetramates, for which different pathways operate as a result of differing ring-chain tautomeric behaviour of the respective intermediate imines.
Co-reporter:Song Wei Benjamin Tan, Christina L. L. Chai and Mark G. Moloney
Organic & Biomolecular Chemistry 2017 - vol. 15(Issue 8) pp:NaN1912-1912
Publication Date(Web):2017/01/31
DOI:10.1039/C6OB02828D
Mono and dihydroxypyrrolidinones are readily available by direct oxygenation of a pyroglutamate-derived bicyclic lactam with high diastereoselectivity, and these may be manipulated further in protected or unprotected form by Grignard addition to a pendant Weinreb amide to give acylhydroxypyrrolidinones, which are analogues of the natural product, pramanicin. Preliminary bioassay against S. aureus and E. coli indicated that some compounds exhibit selective Gram-negative antibacterial activity, and may offer promise for the development of novel systems suitable for antibacterial drug development.
Co-reporter:Yong-Chul Jeong, Muhammad Anwar, Tuan Minh Nguyen, Benjamin Song Wei Tan, Christina Li Lin Chai and Mark G. Moloney
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 19) pp:NaN6669-6669
Publication Date(Web):2011/06/20
DOI:10.1039/C1OB05816A
An efficient strategy for the control of the chemoselectivity in Dieckmann ring closures leading to tetramic acids derived from serine and α-methyl serine is reported, and this provides pathways to diversely substituted systems from a common starting material.
Co-reporter:Song Wei Benjamin Tan, Christina L. L. Chai and Mark G. Moloney
Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 11) pp:NaN1716-1716
Publication Date(Web):2014/02/04
DOI:10.1039/C4OB00095A
An efficient approach for the introduction of 3-acyl side chain groups onto a core tetramate system, which are suitable for further manipulation by nucleophilic displacement or Horner–Wadsworth–Emmons coupling, provides access to a diverse library of substituted tetramates related to two distinct classes of natural products, equisetin and pramanicin. Assessment against S. aureus and E. coli indicated that some compounds exhibit significant antibacterial activity, providing unusual leads for further optimisation in the drug discovery process.
Co-reporter:Nandkishor Chandan, Amber L. Thompson and Mark G. Moloney
Organic & Biomolecular Chemistry 2012 - vol. 10(Issue 39) pp:NaN7868-7868
Publication Date(Web):2012/08/15
DOI:10.1039/C2OB26423D
Substituted pyrrolines are available by ring closure initiated by direct nucleophilic attack of stabilized enolates at the nitrogen of oximes activated with a leaving group, in a process which effectively out-competes the more usual Beckmann rearrangement. Subsequent reduction provides diastereoselective access to the corresponding pyrrolidines. This provides a rapid route to saturated heterocyclic systems from readily available precursors.
Co-reporter:Lawrence Harris, Martin Gilpin, Amber L. Thompson, Andrew R. Cowley and Mark G. Moloney
Organic & Biomolecular Chemistry 2015 - vol. 13(Issue 23) pp:NaN6550-6550
Publication Date(Web):2015/05/05
DOI:10.1039/C5OB00648A
The uncatalysed cycloaddition of substituted diaryldiazo compounds onto bicyclic unsaturated lactams derived from pyroglutamic acid efficiently leads to highly functionalised azatricyclononanes. The products are readily elaborated to deprotected pyroglutamate derivatives, providing rapid access to conformationally constrained amino acids and their analogues. Preliminary assessment of antibacterial activity against one Gram positive and one Gram negative organism indicated high levels of efficacy in some cases.