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McGlacken GP, Fairlamb IJS. 2-Pyrone natural products and mimetics: isolation, characterisation and biological activity. Nat Prod Rep 2005; 22:369-85. [PMID: 16010346 DOI: 10.1039/b416651p] [Citation(s) in RCA: 274] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The review summarises natural products containing the 2-pyrone moiety. An emphasis has been placed upon the biological activity associated with 2-pyrones, particularly with respect to potential therapeutic or anti-microbial agents. Where appropriate, non-natural 2-pyrone analogues are discussed, particularly those derived from natural product lead compounds.
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Collings JC, Parsons AC, Porrès L, Beeby A, Batsanov AS, Howard JAK, Lydon DP, Low PJ, Fairlamb IJS, Marder TB. Optical properties of donor-acceptor phenylene-ethynylene systems containing the 6-methylpyran-2-one group as an acceptor. Chem Commun (Camb) 2005:2666-8. [PMID: 15917913 DOI: 10.1039/b502781k] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Donor-acceptor phenylene ethynylene systems containing the 6-methylpyran-2-one group, synthesized via classic or microwave-assisted Sonogashira cross-coupling, exhibit pronounced solvatochromism in fluorescence suggesting a highly polar excited state; 4-[4-(4-N,N-dihexylaminophenylethynyl)phenylethynyl]-6-methylpyran-2-one has a fluorescence quantum yield >0.9 in cyclohexane.
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Batsanov AS, Collings JC, Fairlamb IJS, Holland JP, Howard JAK, Lin Z, Marder TB, Parsons AC, Ward RM, Zhu J. Requirement for an oxidant in Pd/Cu co-catalyzed terminal alkyne homocoupling to give symmetrical 1,4-disubstituted 1,3-diynes. J Org Chem 2005; 70:703-6. [PMID: 15651824 DOI: 10.1021/jo048428u] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Palladium-catalyzed terminal alkyne dimerization, through oxidative homocoupling, is a useful approach to the synthesis of symmetrical 1,4-diynes. Recent investigations have suggested that this reaction might be accomplished in the absence of intentionally added stoichiometric oxidants (to reoxidize Pd(0) to Pd(II)). In this paper, we have fully addressed the question of whether oxygen (or added oxidant) is required to facilitate this process. The presence of a stoichiometric quantity of air (or added oxidant such as I2) is essential for alkyne dimerization. Excess PPh3 inhibits alkyne dimerization to enyne, which only occurs to a significant extent when the reaction is starved of oxidant. Theoretical studies shed more light on the requirement for an oxidant in the homocoupling reaction in order for the process to be theromodynamically favorable. The employment of I2 as the stoichiometric oxidant appears to be the method of choice. The dual role of Cu both in transmetalation of alkynyl units to Pd(II) and in assisting reoxidation of Pd(0) to Pd(II) is suggested.
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Fairlamb IJS. Asymmetric cycloisomerization of 1,6- and 1,7-enynes by transition-metal catalysts. Angew Chem Int Ed Engl 2005; 43:1048-52. [PMID: 14983437 DOI: 10.1002/anie.200301699] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Fairlamb IJS, Kapdi AR, Lee AF. η2-dba Complexes of Pd(0): The Substituent Effect in Suzuki−Miyaura Coupling. Org Lett 2004; 6:4435-8. [PMID: 15548044 DOI: 10.1021/ol048413i] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The influence of aryl substituents in dibenzylidene acetone (dba) ligands, for Pd(0) complexes, has been evaluated for Suzuki-Miyaura cross-coupling reactions. Electron-withdrawing substituents such as NO(2) or CF(3) deactivate the catalyst species whereas strongly donating substituents such as OMe increase catalytic activity over that of unsubstituted dba ligands. [reaction: see text]
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Fairlamb IJS, Lynam JM, Taylor IE, Whitwood AC. η1-Bound 2-Pyrone Complexes of Molybdenum and Iron: A Synthetic and Structural Study. Organometallics 2004. [DOI: 10.1021/om049523w] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Fairlamb IJS, Marrison LR, Dickinson JM, Lu FJ, Schmidt JP. 2-Pyrones possessing antimicrobial and cytotoxic activities. Bioorg Med Chem 2004; 12:4285-99. [PMID: 15246105 DOI: 10.1016/j.bmc.2004.01.051] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Accepted: 01/27/2004] [Indexed: 10/26/2022]
Abstract
The 2-pyrone sub-unit is found in a number of natural products possessing broad spectrum biological activity. Such compounds are validated as being capable of binding to specific protein domains and able to exert a remarkable range of biological effects. In an effort to identify synthetic 2-pyrones with interesting biological effects, herein we report the synthesis and biological evaluation of 4-substituted-6-methyl-2-pyrones. Synthetic routes to 4-alkyl/alkenyl/aryl/alkynyl-6-methyl-2-pyrones have been developed utilising Sonogashira, Suzuki and Negishi cross-coupling starting from readily available 4-bromo-6-methyl-2-pyrone. Specific conditions for each organometallic protocol were required for successful cross-coupling. In particular, a triethylamine/acetonitrile--base/solvent mixture was crucial to Sonogashira alkynylation of 4-bromo-6-methyl-2-pyrone, whereas thallium carbonate was a mandatory base for the Suzuki cross-coupling of trialkylboranes. The 2-pyrones demonstrate potent inhibitory activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Schizosaccharomyces pombe and Botrytis cinerea. The growth inhibitory activities of selected 2-pyrones were determined in A2780 human ovarian carcinoma and K562 human chronic myelogenous leukaemia cell lines using an in vitro cell culture system (MTT assay). These studies demonstrate that 4-phenylethynyl-, 4-tetrahydropyranylpropargyl ether- and 4-ethynyl-6-methyl-2-pyrones have excellent potential as a new class of anticancer agents.
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Demotie A, Fairlamb IJS, Lu FJ, Shaw NJ, Spencer PA, Southgate J. Synthesis of jaspaquinol and effect on viability of normal and malignant bladder epithelial cell lines. Bioorg Med Chem Lett 2004; 14:2883-7. [PMID: 15125952 DOI: 10.1016/j.bmcl.2004.03.055] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 03/15/2004] [Indexed: 11/25/2022]
Abstract
The synthesis of jaspaquinol 1, a monocyclic diterpene-benzenoid, is reported. Two synthetic routes to this natural product have been developed. The first, utilises a difunctional terpene derivative containing different leaving groups, facilitating the selective introduction of the cyclohexenyl and benzenoid fragments. The alternative route employs a regiospecific Stille cross-coupling reaction to introduce the cyclohexenyl fragment, which occurs without allylic transposition. Preliminary data shows the cell viability of 1 against normal and malignant human bladder epithelial cell lines.
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Fairlamb IJS. Asymmetrische Cycloisomerisierung von 1,6- und 1,7-Eninen mitÜbergangsmetallkatalysatoren. Angew Chem Int Ed Engl 2004. [DOI: 10.1002/ange.200301699] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Beeby A, Bettington S, Fairlamb IJS, Goeta AE, Kapdi AR, Niemelä EH, Thompson AL. A new precatalyst for the Suzuki reaction—a pyridyl-bridged dinuclear palladium complex as a source of mono-ligated palladium(0). NEW J CHEM 2004. [DOI: 10.1039/b401077a] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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137
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Fairlamb IJS, Grant S, Grogan G, Maddrell DA, Nichols JC. A one-pot remote allylic hydroxylation and Baeyer–Villiger oxidation of a bicyclo[3.2.0]hept-2-en-6-one by Cunninghamella echinulata NRRL 3655. Org Biomol Chem 2004; 2:1831-3. [PMID: 15227534 DOI: 10.1039/b406016d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
7-exo-Methyl-7-endo-phenylbicyclo[3.2.0]hept-2-en-6-one 3 undergoes Baeyer-Villiger and allylic oxidation, to yield novel hydroxylactone 8 in good yield by Cunninghamella echinulata NRRL 3655, representing a one step biocatalytic access to a cyclopentanoid scaffold with three chiral centers. Interesting, allylic oxidation occurs with transposition of the double bond.
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Fairlamb IJS, Kapdi AR, Lee AF, Sánchez G, López G, Serrano JL, García L, Pérez J, Pérez E. Mono- and binuclear cyclometallated palladium(ii) complexes containing bridging (N,O-) and terminal (N-) imidate ligands: Air stable, thermally robust and recyclable catalysts for cross-coupling processes. Dalton Trans 2004:3970-81. [PMID: 15558122 DOI: 10.1039/b413886d] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel dinuclear cyclometallated palladium complexes [{Pd(mu-NCO)(C circumflex accent N)}(2)], containing asymmetric imidato -NCO- bridging units have been synthesised [C circumflex accent N = 7,8-benzoquinolyl; -NCO- = succinimidate (1c), phthalimidate (1a-3a) or maleimidate (3c)]. The reaction of these complexes, and the previously reported analogous imidate precursors containing a phenylazophenyl (1a-3a) or 2-pyridylphenyl (1b-3b) backbone, with tertiary phosphines provides novel mononuclear N-bonded imidate derivatives of the general formula [Pd(C circumflex accent N)(imidate)(L)][L = PPh(3), P(4-F-C(6)H(4))(3) or P(4-MeO-C(6)H(4))(3)]. The single crystal structures of [Pd(azb)(phthalimidate)(P(4-MeO-C(6)H(4))(3))](9a) and [Pd(bzq)(phthalimidate)(PPh(3))](7c) have been established. Dinuclear complexes (1a-3a, 1b-3b, 1c-3c) demonstrate outstanding thermal stability in the solid-state, as shown by thermoanalytical techniques. A marked influence of bridging imidate groups on the initial decomposition temperature is observed. The dinuclear and mononuclear derivatives are shown to be active catalysts/precatalysts for the Suzuki-Miyaura cross-coupling reactions of aryl bromides with aryl boronic acids, and the Sonogashira reactions of aryl halides with phenyl acetylene (in the presence and absence of Cu(I) salts). The conversions appear to be dependent, to some extent, on the type of imidate ligand, suggesting a role for these pseudohalides in the catalytic cycle in both cross-coupling processes. Lower catalyst loadings in 'copper-free' Sonogashira cross-couplings favour higher turnover frequencies. We have further determined that these catalysts may be recycled using a poly(ethylene oxide)(PEO)/methanol solvent medium in Suzuki-Miyaura cross-coupling. Once the reaction is complete, product extraction into a hexane/diethyl ether mixture (1 : 1, v/v) gives cross-coupled products in good yields (with purity > 95%). The polar phase can then be re-used several times without appreciable loss of catalytic activity.
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Marrison LR, Dickinson JM, Fairlamb IJS. Suzuki cross-coupling approaches to the synthesis of bioactive 3-substituted and 5-substituted-4-methoxy-6-methyl-2-pyrones. Bioorg Med Chem Lett 2003; 13:2667-71. [PMID: 12873490 DOI: 10.1016/s0960-894x(03)00546-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Suzuki cross-coupling has been used to access a wide range of 3- and 5-substituted 2-pyrones, which show remarkable inhibitory activity against bacteria, yeasts and fungi. 3-Octenyl and 5-octenyl 2-pyrones inhibit human ovarium carcinoma (A2780) and human chronic myelogenous leukaemia (K562) cell lines at the micromolar level.
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Fairlamb IJS, Bäuerlein PS, Marrison LR, Dickinson JM. Pd-catalysed cross coupling of terminal alkynes to diynes in the absence of a stoichiometric additive. Chem Commun (Camb) 2003:632-3. [PMID: 12669860 DOI: 10.1039/b212430k] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An efficient, room temperature procedure for the cross-coupling of a range of terminal alkynes, using standard Sonogashira cross-coupling conditions (Pd/Cu) is presented. At higher reaction temperatures, head-to-tail or head-to-head dimerisation affords 1,3- and 1,4-disubstituted enynes, respectively as minor products.
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Fairlamb IJS, Dickinson JM, O'Connor R, Cohen LH, van Thiel CF. Synthesis and antimicrobial evaluation of farnesyl diphosphate mimetics. Bioorg Chem 2003; 31:80-97. [PMID: 12697170 DOI: 10.1016/s0045-2068(03)00025-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The synthesis and first antimicrobial evaluation of farnesyl diphosphate mimetics are described. Several analogues (10, 12, 13, and 20) are inhibitors of Candida albicans, Shizosaccharomyces pombe, and Saccharomyces cerevisiae. The activities of analogues 10, 12, and 13, which contain a omega-phenyl moiety and a diphosphate isostere, are not attributable to inhibition of sterol biosynthesis via squalene synthase. Two geranyl phenylsulphones (14 and 15) are potent inhibitors of Escherichia coli. Analogue 15 exhibits potent activity towards Salmonella typhimurium and Pseudomonas aeruginosa (MIC-2 microg/mL) and represents the first type of semi-synthetic terpenoid allylic sulphone active against these bacteria.
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Crawforth CM, Burling S, Fairlamb IJS, Taylor RJK, Whitwood AC. Bromobis(triphenylphosphine)(N-succinimide)palladium(ii) as a novel catalyst for Stille cross-coupling reactions. Chem Commun (Camb) 2003:2194-5. [PMID: 13678197 DOI: 10.1039/b304960d] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new palladium catalyst is reported for Stille cross-coupling, namely [Pd(NCOC2H4CO)(PPh3)2Br].
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Marrison LR, Dickinson JM, Fairlamb IJS. Bioactive 4-substituted-6-methyl-2-pyrones with promising cytotoxicity against A2780 and K562 cell lines. Bioorg Med Chem Lett 2002; 12:3509-13. [PMID: 12443764 DOI: 10.1016/s0960-894x(02)00824-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bioactive synthetic 4-substituted-6-methyl-2-pyrones are reported. Various 4-substitutents have been incorporated using Pd-catalysed carbon-carbon bond coupling procedures. Preliminary screening of the 2-pyrones against human ovarian carcinoma (A2780) and human chronic myelogenous leukaemia (K562) cell lines show that 4-alkynyl-6-methyl-2-pyrones have excellent potential as anticancer agents. The pyrones demonstrate broad spectrum antimicrobial activities.
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Fairlamb IJS, Lloyd-Jones GC, Vyskocil S, Kocovský P. Analysis of stereochemical convergence in asymmetric pd-catalysed allylic alkylation reactions complicated by halide and memory effects. Chemistry 2002; 8:4443-53. [PMID: 12355532 DOI: 10.1002/1521-3765(20021004)8:19<4443::aid-chem4443>3.0.co;2-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A quantitative two-term description of memory effects arising in Pd-catalysed allylic alkylation reactions formally proceeding through 'meso'-type pi-allylpalladium intermediates is presented. The utility of this description (stereochemical convergence (sc) and global enantiomeric excess (ee(g))) is demonstrated by application to a series of Pd-catalysed allylic alkylation reactions involving racemic cyclopentenyl esters. Analysis of such reactions, by employing a range of enantiomerically pure monophosphine ligands, reinforces the conclusion that selectivities (enantiomeric excess (ee) values) obtained under standard 'benchmark' type conditions may be very misleading when powerful memory effects are operative. However, by comparison of sc and ee for a given ligand/solvent combination under a range of related conditions, one may predict the limiting ('latent') selectivity that will be obtained when the memory effect is negated. This technique is exemplified with one particular ligand (4 b, 'MAP') for which a number of strategies were employed to find conditions that negate the memory effect and reveal the limiting selectivity of the ligand. These conditions give a higher limiting global selectivity than that obtainable by using standard diastereoisomer equilibration methods such as added halide. Thus, the analysis of sc versus ee(g) also allows subtle changes in selectivity to be discerned. The difference in limiting selectivity (chloride versus non-chloride conditions) is proposed to arise through the nucleophilic attack of neutral monodentate versus cationic bidentate MAP (4 b) or MOP (4 a) complexes.
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Fairlamb IJS, Dickinson JM, O'Connor R, Higson S, Grieveson L, Marin V. Identification of novel mammalian squalene synthase inhibitors using a three-dimensional pharmacophore. Bioorg Med Chem 2002; 10:2641-56. [PMID: 12057653 DOI: 10.1016/s0968-0896(02)00090-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Squalene synthase (E.C. 2.5.1.21) catalyses the reductive dimerisation of farnesyl diphosphate in a [1-4] head to head fashion to form squalene, and is the first committed step in cholesterol biosynthesis. Specific inhibitors of squalene synthase would inhibit cholesterol formation and allow production of other important compounds derived from the cholesterol biosynthetic pathway, namely the ubiquinones (co-enzyme Q(10)), dolichol, and would also allow the isoprenylation process of ras by farnesyl-protein transferase. The construction of a hypothetical squalene synthase three-dimensional pharmacophore is presented. It serves as a template for the identification of several new potential classes of inhibitors. The synthesis, anti-microbial and mammalian pig liver squalene synthase activities of analogues based on the bicyclo[3.2.0]heptane and bicyclo[3.3.0]octane ring systems are reported. Analogues of the latter system are pro-drug type inhibitors and exhibit promising biological activity.
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Fairlamb IJS. 1,2-Bis-N-[2′-(diphenylphosphino)-benzo/naphtho]-1,2-diamino-cyclo-hexane - Trost Modular Ligands. Synlett 2002. [DOI: 10.1055/s-2002-32600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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148
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Bray KL, Fairlamb IJS, Lloyd-Jones GC. Halide redistribution in Pd-catalysed 1,6-diene cycloisomerisation. Chem Commun (Camb) 2001. [DOI: 10.1039/b009356o] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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149
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Fairlamb IJS, Lloyd-Jones GC. On the effect of catalyst loading in Pd-catalysed allylic alkylation. Chem Commun (Camb) 2000. [DOI: 10.1039/b007785m] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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