101
|
Atkin AJ, Williams S, Sawle P, Motterlini R, Lynam JM, Fairlamb IJS. μ2-Alkyne dicobalt(0)hexacarbonyl complexes as carbon monoxide-releasing molecules (CO-RMs): probing the release mechanism. Dalton Trans 2009:3653-6. [DOI: 10.1039/b904627p] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
102
|
Zhang WQ, Atkin AJ, Thatcher RJ, Whitwood AC, Fairlamb IJS, Lynam JM. Diversity and design of metal-based carbon monoxide-releasing molecules (CO-RMs) in aqueous systems: revealing the essential trends. Dalton Trans 2009:4351-8. [DOI: 10.1039/b822157j] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
103
|
Bäuerlein PS, Fairlamb IJS, Jarvis AG, Lee AF, Müller C, Slattery JM, Thatcher RJ, Vogt D, Whitwood AC. Ion-tagged π-acidic alkene ligands promote Pd-catalysed allyl–aryl couplings in an ionic liquid. Chem Commun (Camb) 2009:5734-6. [DOI: 10.1039/b906823f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
104
|
Fairlamb IJS. pi-Acidic alkene ligand effects in Pd-catalysed cross-coupling processes: exploiting the interaction of dibenzylidene acetone (dba) and related ligands with Pd(0) and Pd(II). Org Biomol Chem 2008; 6:3645-56. [PMID: 18843391 DOI: 10.1039/b811772a] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
pi-Acidic alkene (olefin) ligands positively influence Pd-catalysed cross-coupling processes, interacting with both palladium(0) and palladium(ii) species, in some cases stabilising key catalytic intermediates. Rates of oxidative addition and reductive elimination are both affected. In certain cases, beta-hydrogen elimination can be slowed down by pi-acidic alkenes, which opens up new reaction pathways (e.g. interception of sigma-alkylpalladium(ii) species by appropriate nucleophiles). pi-Acidic alkene ligands can act independently or in a synergistic fashion with another two-electron donor ligand (e.g. amine, phosphine or N-heterocyclic carbene). The purpose of this perspective article is to highlight the impressive results that can be obtained using pi-acidic alkene ligands, with a particular focus on dibenzylidene acetone (dba) derivatives. Other types of alkene ligands, e.g. macrocyclic alkenes, are also discussed.
Collapse
|
105
|
Sawle P, Moulton BE, Jarzykowska M, Green CJ, Foresti R, Fairlamb IJS, Motterlini R. Structure−Activity Relationships of Methoxychalcones as Inducers of Heme Oxygenase-1. Chem Res Toxicol 2008; 21:1484-94. [DOI: 10.1021/tx800115g] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
106
|
Moulton BE, Dong H, O'Brien CT, Duckett SB, Lin Z, Fairlamb IJS. A natural light induced regioselective 6π-electrocyclisation–oxidative aromatisation reaction: experimental and theoretical insights. Org Biomol Chem 2008; 6:4523-32. [PMID: 19039360 DOI: 10.1039/b811284c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
107
|
Burns MJ, Fairlamb IJS, Kapdi AR, Sehnal P, Taylor RJK. Simple Palladium(II) Precatalyst for Suzuki−Miyaura Couplings: Efficient Reactions of Benzylic, Aryl, Heteroaryl, and Vinyl Coupling Partners. Org Lett 2007; 9:5397-400. [DOI: 10.1021/ol702291r] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
108
|
Moulton BE, Duhme-Klair AK, Fairlamb IJS, Lynam JM, Whitwood AC. A Rationale for the Linear Correlation of Aryl Substituent Effects in Iron(0) Tricarbonyl Complexes Containing α,β-Unsaturated Enone (Chalcone) Ligands. Organometallics 2007. [DOI: 10.1021/om7006425] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
109
|
Fairlamb IJS, Lee AF. In-Silico Prediction of Pd-Catalyzed Cross-Coupling Processes: Dibenzylidene Acetone (dba) Ligand Control. Organometallics 2007. [DOI: 10.1021/om700617r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
110
|
Fairlamb IJS, Tommasi S, Moulton BE, Zheng W, Lin Z, Whitwood AC. Conformational Flexibility in a Carbobicyclic Diphosphinite Ligand. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700484] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
111
|
McGlacken GP, O'Brien CT, Whitwood AC, Fairlamb IJS. Chiral Mono- and Bis-annelated Cyclopentadienyl Ligands Derived from Tartaric Acid: Synthesis of [(η5-Cyclopentadienyl)RuCl(cod)] and [(η5-Cyclopentadienyl)(η6-benzene)Ru]PF6 Derivatives. Organometallics 2007. [DOI: 10.1021/om700393b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
112
|
Fairlamb IJS. Regioselective (site-selective) functionalisation of unsaturated halogenated nitrogen, oxygen and sulfur heterocycles by Pd-catalysed cross-couplings and direct arylation processes. Chem Soc Rev 2007; 36:1036-45. [PMID: 17576472 DOI: 10.1039/b611177g] [Citation(s) in RCA: 315] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This tutorial review focuses on several practical synthetic transformations utilising palladium catalysis that facilitate the synthesis of functionalized unsaturated heterocycles in a regioselective (site-selective) manner. Cross-couplings of electron-deficient, electron-neutral and electron-rich unsaturated halogenated heterocycles with various organometallic reagents, and other types of nucleophiles, are detailed. Direct arylation of electron-rich unsaturated heterocyclic compounds by C-H functionalization is also presented.
Collapse
|
113
|
S. Fairlamb IJ. Transition metals in organic synthesis: cross-coupling, C–H activation processes and cyclisation strategies. ACTA ACUST UNITED AC 2007. [DOI: 10.1039/b614710k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
114
|
Fairlamb IJS, Grant S, McCormack P, Whittall J. Alkoxy- and amidocarbonylation of functionalised aryl and heteroaryl halides catalysed by a Bedford palladacycle and dppf: a comparison with the primary Pd(ii) precursors (PhCN)2PdCl2 and Pd(OAc)2. Dalton Trans 2007:859-65. [PMID: 17297513 DOI: 10.1039/b615874a] [Citation(s) in RCA: 37] [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
The versatility of a Bedford-type palladacycle , namely [{Pd(micro-Cl){kappa2-P,C-P(OC6H(2)-2,4-tBu2)(OC6H(3)-2,4-tBu2)2}}2], as a primary Pd source, in combination with the ligand bis-1,1'-(diphenylphosphino)ferrocene (dppf) has been established in carbonylation reactions of aryl and heteroaryl bromides with methanol, piperidine and related nucleophiles. Palladacycle has been compared with other primary Pd sources, e.g. (PhCN)2PdCl2 and Pd(OAc)2. The efficacy of the carbonylation processes appear to be linked to the [Pd] concentration, substrate : catalyst ratio, CO pressure and reaction temperature. In amidocarbonylation, double carbonylation is observed for certain organohalides. In the case of 2,5-dibromopyridine, regioselective amination (Hartwig-Buchwald type) also occurs as a side-reaction.
Collapse
|
115
|
Fairlamb IJS, Lynam JM, Moulton BE, Taylor IE, Duhme-Klair AK, Sawle P, Motterlini R. η1-2-Pyrone metal carbonyl complexes as CO-releasing molecules (CO-RMs): A delicate balance between stability and CO liberation. Dalton Trans 2007:3603-5. [PMID: 17700821 DOI: 10.1039/b707377a] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An evaluation of the CO releasing ability of iron(II) and molybdenum(II) complexes has facilitated the discovery of the most rapid CO releaser, namely [Mo(CO)(3)(eta(5)-C(5)H(5))(eta(1)-{O}-C{=O}-O-CMe=CH-COMe=CBr)]BF(4) (CORM-F10), reported to date. The rate of CO release is related to the overall solution phase stability of the transition metal carbonyl complex. The cytotoxicity and vasodilatory properties of CORM-F10 have been determined.
Collapse
|
116
|
Fairlamb IJS, Kapdi AR, Lee AF, McGlacken GP, Weissburger F, de Vries AHM, Schmieder-van de Vondervoort L. Exploiting Noninnocent (E,E)-Dibenzylideneacetone (dba) Effects in Palladium(0)-Mediated Cross-Coupling Reactions: Modulation of the Electronic Properties of dba Affects Catalyst Activity and Stability in Ligand and Ligand-Free Reaction Systems. Chemistry 2006; 12:8750-61. [PMID: 16952128 DOI: 10.1002/chem.200600473] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The reactivity of palladium(0) complexes, [Pd(0) (2)(dba-n,n'-Z)(3)] (n,n'-Z=4,4'-F; 4,4'-CF(3); 4,4'-H; 4,4'-MeO) and [Pd(0)(dba-n,n'-Z)(2)] (n,n'-Z=4,4'-CF(3); 4,4'-H; 3,3',5,5'-OMe), used as precursor catalysts with suitable donor ligands (e.g. phosphines, N-heterocyclic carbenes), has been correlated in several palladium(0)-mediated cross-coupling processes. Increasing the electron density on the aryl moiety of the dba-n,n'-Z ligand increases the overall catalytic activity in the majority of these processes. This effect primarily derives from destabilization of the L(n)Pd(0)-eta(2)-dba interaction (in dpi-pi* synergic bonding, n=1 or 2), which ultimately increases the global concentration of catalytically active L(n)Pd(0) available for reaction with aryl halide in the first committed step in the general catalytic cycle(s) (oxidative addition). Decreasing electron density on the aryl moiety of the dba-n,n'-Z ligand stabilizes the Pd(0)-eta(2)-dba interaction, reducing catalytic activity. The specific type of dba-n,n'-Z ligand appears to also play a stabilizing role in the catalytic cycle, preventing Pd agglomeration, and increasing catalyst longevity. A subtle balance therefore exists between the L(n)Pd(0) concentration (and the associated catalytic activity) and catalyst longevity. Changing the type of dba-n,n'-Z ligand controls the concentration of L(n)Pd(0) and the rate of the oxidative addition step, and not other intimate steps within the catalytic cycle(s), for example, transmetallation (or carbopalladation) and reductive elimination. The role of dba-n,n'-Z ligands in Heck arylation is more convoluted and dependent on the alkene substrate employed, although trends have emerged. Changes in the structure of dba-n,n'-Z had a minimal affect on Buchwald-Hartwig aryl amination processes. A secondary Michael reaction of dba-n,n'-Z with amine and/or base effectively lessens its interference in the catalytic cycle.
Collapse
|
117
|
Ariafard A, Lin Z, Fairlamb IJS. Effect of the Leaving Ligand X on Transmetalation of Organostannanes (vinylSnR3) with LnPd(Ar)(X) in Stille Cross-Coupling Reactions. A Density Functional Theory Study. Organometallics 2006. [DOI: 10.1021/om0607705] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
118
|
Sawle P, Hammad J, Fairlamb IJS, Moulton B, O'Brien CT, Lynam JM, Duhme-Klair AK, Foresti R, Motterlini R. Bioactive properties of iron-containing carbon monoxide-releasing molecules. J Pharmacol Exp Ther 2006; 318:403-10. [PMID: 16603670 DOI: 10.1124/jpet.106.101758] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Carbon monoxide-releasing molecules (CO-RMs) are compounds capable of delivering controlled amounts of CO within a cellular environment. Ruthenium-based carbonyls [tricarbonyldichloro ruthenium(II) dimer and tricarbonylchloro-(glycinato)ruthenium(II)] and boronacorbonates (sodium boranocarbonate) have been shown to promote vasodilatory, cardioprotective, and anti-inflammatory activities in a variety of experimental models. Here, we extend our previous studies by showing that eta-4-(4-bromo-6-methyl-2-pyrone)tricarbonyl iron (0) (CORM-F3), an irontricarbonyl complex that contains a 2-pyrone motif, liberates CO in vitro and exerts pharmacological actions that are typical of CO gas. Specifically, CORM-F3 caused vasorelaxation in isolated aortic rings and inhibited the inflammatory response (e.g., nitrite production) of RAW264.7 macrophages stimulated with endotoxin in a dose-dependent fashion. By analyzing the rate of CO release, we found that when the bromide at the 4-position of the 2-pyrone CORM-F3 is substituted with a chloride group [eta-4-(4-chloro-6-methyl-2-pyrone)tricarbonyl iron (0) (CORM-F8)], the rate of CO release is significantly decreased (4.5-fold), and a further decrease is observed when the 4- and 6-positions are substituted with a methyl group [eta-4-(4-methyl-6-methyl-2-pyrone)tricarbonyl iron (0) (CORM-F11)] or a hydrogen [eta-4-(4-chloro-2-pyrone)tricarbonyl iron (0) (CORM-F7)], respectively. Interestingly, the compounds containing halogens at the 4-position and the methyl at the 6-position of the 2-pyrone ring (CORM-F3 and CORM-F8) were found to be less cytotoxic compared with other CO-RMs when tested in RAW246.7 macrophages. Thus, iron-based carbonyls mediate pharmacological responses that are achieved through liberation of CO and the nature of the substituents in the organic ligand have a profound effect on both the rate of CO release and cytotoxicity.
Collapse
|
119
|
Macé Y, Kapdi AR, Fairlamb IJS, Jutand A. Influence of the dba Substitution on the Reactivity of Palladium(0) Complexes Generated from Pd02(dba-n,n‘-Z)3 or Pd0(dba-n,n‘-Z)2 and PPh3 in Oxidative Addition with Iodobenzene. Organometallics 2006. [DOI: 10.1021/om0510876] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
120
|
Fairlamb IJS, Duhme-Klair AK, Lynam JM, Moulton BE, O'Brien CT, Sawle P, Hammad J, Motterlini R. η4-Pyrone iron(0)carbonyl complexes as effective CO-releasing molecules (CO-RMs). Bioorg Med Chem Lett 2006; 16:995-8. [PMID: 16289810 DOI: 10.1016/j.bmcl.2005.10.085] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 10/24/2005] [Accepted: 10/26/2005] [Indexed: 11/24/2022]
Abstract
The CO-releasing properties of iron(0)tricarbonyl complexes bearing a 2-pyrone ligand have been evaluated. In this report, we demonstrate that the intrinsic stability of the (eta4-2-pyrone)Fe(CO)3 complex influences the extent and rate of CO release, which is affected by the presence of a halogen substituent on the 2-pyrone ring. The cell viability index has been highlighted for the active carbon monoxide-releasing molecules (CO-RMs), demonstrating that these complexes and related derivatives are a promising new class of compounds with potential therapeutic applications.
Collapse
|
121
|
Bonsor D, Butz SF, Solomons J, Grant S, Fairlamb IJS, Fogg MJ, Grogan G. Ligation independent cloning (LIC) as a rapid route to families of recombinant biocatalysts from sequenced prokaryotic genomes. Org Biomol Chem 2006; 4:1252-60. [PMID: 16557313 DOI: 10.1039/b517338h] [Citation(s) in RCA: 72] [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
A technique is presented for the high throughput generation of families of recombinant biocatalysts sourced from prokaryotic genomes, providing rapid access to the naturally evolved diversity of enzyme specificity for biocatalyst discovery. The method exploits a novel ligation independent cloning strategy, based on the locally engineered vector pET-YSBLIC and has been used for the rapid generation of a suite of expression plasmids containing genes encoding a family of six Baeyer-Villiger monooxygenases (BVMOs) from Mycobacterium tuberculosis H37Rv (MTb). The six resultant recombinant strains of E. coli B834 (DE3) expressing the genes were assayed for oxygenating activity in respect of the target reaction; the resolution of bicyclo[3.2.0]hept-2-en-6-one. The analysis of biotransformations catalysed by growing cells of E. coli was complicated by the production of indole in the reaction mixtures, possibly resulting from the in vivo activity of E. coli tryptophanase. Four of the recombinant strains expressing different BVMOs catalysed the oxidation of one or more of four screening substrates, well above controls that had been transformed with the re-ligated parent vector. One of the recombinant strains, E. coli B834 (DE3) pDB5, expressing the Rv3049c gene from MTb, was found to effectively resolve the target substrate, yielding a 19% yield of (1R, 5S)-(+)-bicyclo[3.2.0]hept-2-en-6-one with >95% enantiomeric excess in a 4 L fermentation reaction.
Collapse
|
122
|
Fairlamb IJS, McGlacken GP, Weissberger F. Ruthenium(ii)-catalysed cycloisomerisation of 1,6-dienes by focused microwave dielectric heating: improved rates and selectivities leading to exo-methylenecyclopentanes. Chem Commun (Camb) 2006:988-90. [PMID: 16491185 DOI: 10.1039/b513798e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We herein report the effect of microwave dielectric heating in the Ru-catalysed cycloisomerisation of 1,6-dienes. Substantially improved reaction rates are attained for a series of 1,6-diene substrates, with equivalent or higher isomeric purity than conventional thermal heating.
Collapse
|
123
|
Fairlamb IJS. Transition metals in organic synthesis: cross-coupling and C–H activation processes. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b515096p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
124
|
Fairlamb IJS, Taylor RJK, Serrano JL, Sanchez G. Halide and pseudohalide effects in Pd-catalysed cross-coupling reactions. NEW J CHEM 2006. [DOI: 10.1039/b605699g] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
125
|
Fairlamb IJS, O'Brien CT, Lin Z, Lam KC. Regioselectivity in the Sonogashira coupling of 4,6-dichloro-2-pyrone. Org Biomol Chem 2006; 4:1213-6. [PMID: 16557307 DOI: 10.1039/b518232h] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Sonogashira cross-coupling of 4,6-dichloro-2-pyrone with terminal acetylenes proceeds in good yields and high regioselectivity for the 6-position; dibenzylidene acetone (dba) type ligands play a non-innocent role in reactions mediated by Pd(dba)2/PPh3; theoretical studies indicate that C-6 oxidative addition is favoured both kinetically and thermodynamically.
Collapse
|