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Ulrich S Schubert - One of the best experts on this subject based on the ideXlab platform.
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catalytic applications of Terpyridines and their transition metal complexes
ChemInform, 2012Co-Authors: Andreas Winter, George R Newkome, Ulrich S SchubertAbstract:The coordination compounds of the tridentate oligopyridine ligand 2,2′:6′,2′′-terpyridine (tpy) are utilized in very different fields of research, such as materials science (e.g. photovoltaics), biomedicinal chemistry (e.g. DNA intercalation), and organometallic catalysis. Applications in the latter area have arisen from initial reports on electro- or photochemical processes and, today, a broad range of reactions—from artificial photosynthesis (water splitting) to biochemical and organic transformations as well as polymerization reactions—have been catalyzed by Terpyridines and their transition metal complexes. In this review, the scope and the limitations of these applications, which emerged particularly in organic and macromolecular chemistry, will be evaluated.
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the marriage of Terpyridines and inorganic nanoparticles synthetic aspects characterization techniques and potential applications
Advanced Materials, 2011Co-Authors: Andreas Winter, Martin D Hager, George R Newkome, Ulrich S SchubertAbstract:The utilization of supramolecular chemistry, i.e., metal-to-ligand coordination, in the field of nanotechnology is evaluated with respect to 2,2':6',2″-terpyridine, as tridentate metal binding site. Stabilization as well as directed self-assembly of nanometer-sized materials into ordered arrays are the most widely studied targets of current research. Moreover, energy- and/or electron-transfer processes are enabled when redox-active terpyridine complexes are bound to (semi)conducting species (e.g., fullerenes, polyoxometalates)-thus, applications in nanoelectronics and catalysis are currently arising from these hybrid materials. Progress made in these fields, resulting from the marriage of Terpyridines (as well as their metal complexes) and nanostructures, is summarized in this Review Article.
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advances in the field of π conjugated 2 2 6 2 Terpyridines
Chemical Society Reviews, 2011Co-Authors: Andreas Wild, Florian Schlutter, Andreas Winter, Ulrich S SchubertAbstract:This critical review summarizes the research progress made in the field of π-conjugated Terpyridines within the last decade. Supramolecular materials based on metal ion complexes of 2,2′:6′,2″-terpyridine derivatives have found manifold potential applications—from opto-electronic devices to life science. In this contribution, synthetic strategies towards π-conjugated Terpyridines and their incorporation into advanced supramolecular architectures are evaluated. Applications as photoactive species in, e.g., photovoltaic devices, polymer light-emitting diodes (PLEDSs) and nanotechnology are discussed comprehensively (523 references).
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complexation of terpyridine containing dextrans toward water soluble supramolecular structures
Macromolecular Rapid Communications, 2010Co-Authors: Andreas Wild, Stephanie Hornig, Florian Schlutter, Jurgen Vitz, Christian Friebe, Martin D Hager, Andreas Winter, Ulrich S SchubertAbstract:Dextran was functionalized with 6-(2,2':6',2″-terpyridin-4'-yloxy)-hexanoic acid using two different ratios of terpyridine to dextran, leading to terpyridine-functionalized dextran esters possessing different degrees of substitution (DS = 0.23-0.41). The intra- and intermolecular complexation behavior of both functionalized biopolymers was studied using Fe(II) metal ions as well as activated Ru(III) complexes. The complexation behavior in the first case was studied by UV-visible and viscosity titration experiments. In the latter case, a water soluble comb-polymer could be obtained when using a PEG- functionalized terpyridine Ru(II) moiety for complexation. Moreover, nanoprecipitation was applied to self-assemble the functionalized dextrans into nanoparticles.
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π conjugated 2 2 6 2 bis Terpyridines systematical tuning of the optical properties by variation of the linkage between the Terpyridines and the π conjugated system
European Journal of Organic Chemistry, 2010Co-Authors: Andreas Wild, Christian Friebe, Martin D Hager, Andreas Winter, Ulrich S Schubert, Ulrichwalter GrummtAbstract:2,2':6',2"-Terpyridines bearing well-defined π-conjugated substituents at the 4'-position are known to exhibit interesting electronic and optical properties. The systematic variation of both the spacer unit and the linker in conjugated bis-(Terpyridines) has resulted in a library of π-conjugated systems, enabling the study of the structure―property relationships of these materials. We have proven the Huisgen 1,3-dipolar cycloaddition reaction to be a versatile tool for connecting conjugated systems, even though the conjugation is hindered by the introduced triazole moiety. All the terpyridine derivatives were fully characterized by 1 H and 13 C NMR spectroscopy, UV/Vis absorption and emission measurements as well as MALDI-TOF MS. Thin films of the materials were produced by spin-coating and subsequently characterized. Because tuning of the band gap of the materials over a wide range is possible, quantum yields of up to 85 % and extinction coefficients of around 100000 M -1 cm -1 could be observed, the compounds might be promising candidates for the design of new functional supramolecular materials.
Catherine E. Housecroft - One of the best experts on this subject based on the ideXlab platform.
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switching the conformation of 3 2 6 3 tpy domains in 4 4 n alkyloxyphenyl 3 2 6 3 Terpyridines
Molecules, 2020Co-Authors: Dalila Rocco, Edwin C Constable, Alessandro Prescimone, Catherine E. HousecroftAbstract:The preparation and characterization of 4'-(4-n-octyloxyphenyl)-3,2':6',3″-terpyridine (8) and 4'-(4-n-nonyloxyphenyl)-3,2':6',3″-terpyridine (9) are reported. The single crystal structures of 4'-(4-n-hexyloxyphenyl)-3,2':6',3″-terpyridine (6), 4'-(4-n-heptyloxyphenyl)-3,2':6',3″-terpyridine (7), and compounds 8 and 9 have been determined. The conformation of the 3,2':6',3″-tpy unit is trans,trans in 6 and 7, but switches to cis,trans in 8 and 9. This is associated with significant changes in the packing interactions with a more dominant role for van der Waals interactions between adjacent n-alkyloxy chains and C-Hmethylene... π interactions in 8 and 9. The solid-state structures of 6 and 7 with the n-hexyloxy and n-heptyloxy chains feature interwoven sheets of supramolecular assemblies of molecules, with pairs of n-alkyloxy chains threaded through cavities in an adjacent sheet.
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synthesis of Terpyridines simple reactions what could possibly go wrong
Molecules, 2019Co-Authors: Dalila Rocco, Catherine E. Housecroft, Edwin C ConstableAbstract:The preparation of 24-functionalized 12,22:26,32-Terpyridines (4'-functionalized 3,2:6',3''-Terpyridines) by the reaction of three 4-alkoxybenzaldehydes with 3-acetylpyridine and ammonia was investigated; under identical reaction conditions, two (R = nC4H9, C2H5) gave the expected products whereas a third (R = nC3H7) gave only a cyclohexanol derivative derived from the condensation of three molecules of 3-acetylpyridine with two of 4-(n-propoxy)benzaldehyde. A comprehensive survey of ''unexpected'' products from reactions of ArCOCH3 derivatives with aromatic aldehydes is presented. Three different types of alternative product are identified.
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Synthesis of Terpyridines: Simple Reactions—What Could Possibly Go Wrong?
'MDPI AG', 2019Co-Authors: Dalila Rocco, Catherine E. Housecroft, Edwin C ConstableAbstract:The preparation of 24-functionalized 12,22:26,32-Terpyridines (4′-functionalized 3,2:6′,3″-Terpyridines) by the reaction of three 4-alkoxybenzaldehydes with 3-acetylpyridine and ammonia was investigated; under identical reaction conditions, two (R =nC4H9, C2H5) gave the expected products whereas a third (R = nC3H7) gave only a cyclohexanol derivative derived from the condensation of three molecules of 3-acetylpyridine with two of 4-(n-propoxy)benzaldehyde. A comprehensive survey of “unexpected” products from reactions of ArCOCH3 derivatives with aromatic aldehydes is presented. Three different types of alternative product are identified
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Substituent Effects in the Crystal Packing of Derivatives of 4′-Phenyl-2,2′:6′,2″-Terpyridine
'MDPI AG', 2019Co-Authors: Maximilian Y. Klein, Edwin C Constable, Alessandro Prescimone, Mariia Karpacheva, Catherine E. HousecroftAbstract:We report the preparation of a series of new 4′-substituted 2,2′:6′,2″-Terpyridines: 4′-(3,5-dimethylphenyl)-2,2′:6′,2″-terpyridine (2), 4′-(3-fluoro-5-methylphenyl)-2,2′:6′,2″-terpyridine (3), 4′-(3,5-difluorophenyl)-2,2′:6′,2″-terpyridine (4), and 4′-(3,5- bis(trifluoromethyl)phenyl)-2,2′:6′,2″-terpyridine (5). The compounds have been characterized by mass spectrometry, solid-state IR spectroscopy and solution NMR and absorption spectroscopies. The single-crystal X-ray diffraction structures of 3, 5 and 6·EtOH (6 = 4′-(3,5-bis(tert-butyl)phenyl)-2,2′:6′,2″-terpyridine) have been elucidated. The molecular structures of the compounds are unexceptional. Since 3 and 5 crystallize without lattice solvent, we are able to understand the influence of introducing substituents in the 4′-phenyl ring and compare the packing in the structures with that of the previously reported 4′-phenyl-2,2′:6′,2″-terpyridine (1). On going from 1 to 3, face-to-face π-stacking of pairs of 3-fluoro-5-methylphenyl rings contributes to a change in packing from a herringbone assembly in 1 with no ring π-stacking to a layer-like packing. The latter arises through a combination of π-stacking of aromatic rings and N…H⁻C hydrogen bonding. On going from 3 to 5, N…H⁻C and F…H⁻C hydrogen-bonding is dominant, supplemented by π-stacking interactions between pairs of pyridine rings. A comparison of the packing of molecules of 6 with that in 1, 3 and 5 is difficult because of the incorporation of solvent in 6·EtOH
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4 functionalized 2 2 6 2 Terpyridines as the nˆn domain in ir cˆn 2 nˆn pf6 complexes
Journal of Organometallic Chemistry, 2016Co-Authors: Daniel P Ris, Edwin C Constable, Gabriel E Schneider, Cathrin D Ertl, Emanuel Kohler, Thomas Muntener, Markus Neuburger, Catherine E. HousecroftAbstract:Abstract The cyclometallated iridium(III) complexes [Ir(ppy)2(NˆN)][PF6] (Hppy = 2-phenylpyridine) with NˆN = 4′-chloro-2,2′:6′,2″-terpyridine (1), 4′-methoxy-2,2′:6′,2″-terpyridine (2), 4′-ethoxy-2,2′:6′,2″-terpyridine (3), 4′-methylthio-2,2′:6′,2″-terpyridine (4), 4′-phenylthio-2,2′:6′,2″-terpyridine (5) and 4′-dimethylamino-2,2′:6′,2″-terpyridine (6) are reported including the single crystal structures of 2{[Ir(ppy)2(1)][PF6]}·0.6Et2O·CH2Cl2, [Ir(ppy)2(5)][PF6]·0.5CH2Cl2 and [Ir(ppy)2(6)][PF6]. The single crystal structure of [Ir(ppy)2(3)]Cl·2H2O·MeCN is also reported. In each complex, the 2,2′:6′,2″-terpyridine (tpy) ligand binds to the metal centre in a bidentate fashion with the non-coordinated pyridine ring folded into the coordination sphere and engaging in a pyridine–phenyl π-stacking interaction. Solution NMR spectra are consistent with hindered rotation of the non-coordinated pyridine ring at 298 K, with intra-cation CH…N(pyridine) hydrogen bond formation between adjacent [ppy]– and tpy ligands. Trends in the electrochemical HOMO–LUMO gaps and emission maxima of the complexes (in CH2Cl2 solution) are consistent with the electron-withdrawing or releasing properties of the 4′-tpy substituent; in degassed solution, [Ir(ppy)2(6)][PF6] has a quantum yield of 24.8% and emission lifetime of 441 ns, while the other complexes exhibit significantly lower quantum yields and shorter lifetimes.
O N Chupakhin - One of the best experts on this subject based on the ideXlab platform.
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an efficient synthetic approach to 4 5 5 triaryl 2 2 6 2 Terpyridines
Tetrahedron Letters, 2016Co-Authors: Dmitry S Kopchuk, Vladimir L Rusinov, Grigory A Kim, Nikolay V Chepchugov, Grigory V Zyryanov, Igor S Kovalev, O N ChupakhinAbstract:An efficient synthetic approach is proposed to construct 4′,5,5″-triaryl-2,2′:6′,2″-Terpyridines using two methods of pyridine ring construction, that is, the Weiss method and the ‘1,2,4-triazine’ methodology. Due to the use of ‘1,2,4-triazine’ methodology in the last step, aza-analogues of Terpyridines as well as cycloalkane-annulated Terpyridines have been synthesized which are inaccessible by other reported methods. The presented approach involves the use of readily available reagents and simple procedures.
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an efficient route to 5 5 diaryl 2 2 6 2 Terpyridines through 2 6 bis 1 2 4 triazin 3 yl pyridines
Tetrahedron Letters, 2005Co-Authors: Valery N Kozhevnikov, Dmitry N Kozhevnikov, Olga V Shabunina, Vladimir L Rusinov, O N ChupakhinAbstract:Abstract A new route to substituted 2,2′:6′,2″-Terpyridines based on a new method for the synthesis of substituted 2,6-bis(1,2,4-triazin-3-yl)pyridines and their inverse electron demand Diels–Alder reaction is shown to be an efficient strategy for the synthesis of structurally diverse terpyridine ligands.
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a versatile strategy for the synthesis of functionalized 2 2 bi and 2 2 6 2 Terpyridines via their 1 2 4 triazine analogues
Journal of Organic Chemistry, 2003Co-Authors: Valery N Kozhevnikov, Dmitry N Kozhevnikov, Vladimir L Rusinov, O N Chupakhin, Tatiana V Nikitina, Manfred Zabel, Burkhard KonigAbstract:A general synthetic route for the synthesis of functionalized bi- and Terpyridines is reported. Functionalized 1,2,4-triazene 4-oxides 7 and 8-obtained from the reaction of hydrazones 1 with pyridine aldehydes and followed by oxidation-are functionalized by introduction of a cyano group via nucleophilic aromatic substitution. The thus-obtained 5-cyano-1,2,4-triazines 9 and 10 undergo facile inverse-electron-demand Diels-Alder reactions with enamines and alkenes to yield functionalized bi- and Terpyridines, respectively. The substituent at position 6 of the 1,2,4-triazene 4-oxides must be aromatic or heteroaromatic in order to allow their facile synthesis, but other substituents and reagents may vary. Each step of the synthetic route allows diversification, which makes the approach particularly useful for the facile synthesis of a large variety of functionalized bi- and Terpyridines.
Edwin C Constable - One of the best experts on this subject based on the ideXlab platform.
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switching the conformation of 3 2 6 3 tpy domains in 4 4 n alkyloxyphenyl 3 2 6 3 Terpyridines
Molecules, 2020Co-Authors: Dalila Rocco, Edwin C Constable, Alessandro Prescimone, Catherine E. HousecroftAbstract:The preparation and characterization of 4'-(4-n-octyloxyphenyl)-3,2':6',3″-terpyridine (8) and 4'-(4-n-nonyloxyphenyl)-3,2':6',3″-terpyridine (9) are reported. The single crystal structures of 4'-(4-n-hexyloxyphenyl)-3,2':6',3″-terpyridine (6), 4'-(4-n-heptyloxyphenyl)-3,2':6',3″-terpyridine (7), and compounds 8 and 9 have been determined. The conformation of the 3,2':6',3″-tpy unit is trans,trans in 6 and 7, but switches to cis,trans in 8 and 9. This is associated with significant changes in the packing interactions with a more dominant role for van der Waals interactions between adjacent n-alkyloxy chains and C-Hmethylene... π interactions in 8 and 9. The solid-state structures of 6 and 7 with the n-hexyloxy and n-heptyloxy chains feature interwoven sheets of supramolecular assemblies of molecules, with pairs of n-alkyloxy chains threaded through cavities in an adjacent sheet.
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synthesis of Terpyridines simple reactions what could possibly go wrong
Molecules, 2019Co-Authors: Dalila Rocco, Catherine E. Housecroft, Edwin C ConstableAbstract:The preparation of 24-functionalized 12,22:26,32-Terpyridines (4'-functionalized 3,2:6',3''-Terpyridines) by the reaction of three 4-alkoxybenzaldehydes with 3-acetylpyridine and ammonia was investigated; under identical reaction conditions, two (R = nC4H9, C2H5) gave the expected products whereas a third (R = nC3H7) gave only a cyclohexanol derivative derived from the condensation of three molecules of 3-acetylpyridine with two of 4-(n-propoxy)benzaldehyde. A comprehensive survey of ''unexpected'' products from reactions of ArCOCH3 derivatives with aromatic aldehydes is presented. Three different types of alternative product are identified.
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Synthesis of Terpyridines: Simple Reactions—What Could Possibly Go Wrong?
'MDPI AG', 2019Co-Authors: Dalila Rocco, Catherine E. Housecroft, Edwin C ConstableAbstract:The preparation of 24-functionalized 12,22:26,32-Terpyridines (4′-functionalized 3,2:6′,3″-Terpyridines) by the reaction of three 4-alkoxybenzaldehydes with 3-acetylpyridine and ammonia was investigated; under identical reaction conditions, two (R =nC4H9, C2H5) gave the expected products whereas a third (R = nC3H7) gave only a cyclohexanol derivative derived from the condensation of three molecules of 3-acetylpyridine with two of 4-(n-propoxy)benzaldehyde. A comprehensive survey of “unexpected” products from reactions of ArCOCH3 derivatives with aromatic aldehydes is presented. Three different types of alternative product are identified
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Substituent Effects in the Crystal Packing of Derivatives of 4′-Phenyl-2,2′:6′,2″-Terpyridine
'MDPI AG', 2019Co-Authors: Maximilian Y. Klein, Edwin C Constable, Alessandro Prescimone, Mariia Karpacheva, Catherine E. HousecroftAbstract:We report the preparation of a series of new 4′-substituted 2,2′:6′,2″-Terpyridines: 4′-(3,5-dimethylphenyl)-2,2′:6′,2″-terpyridine (2), 4′-(3-fluoro-5-methylphenyl)-2,2′:6′,2″-terpyridine (3), 4′-(3,5-difluorophenyl)-2,2′:6′,2″-terpyridine (4), and 4′-(3,5- bis(trifluoromethyl)phenyl)-2,2′:6′,2″-terpyridine (5). The compounds have been characterized by mass spectrometry, solid-state IR spectroscopy and solution NMR and absorption spectroscopies. The single-crystal X-ray diffraction structures of 3, 5 and 6·EtOH (6 = 4′-(3,5-bis(tert-butyl)phenyl)-2,2′:6′,2″-terpyridine) have been elucidated. The molecular structures of the compounds are unexceptional. Since 3 and 5 crystallize without lattice solvent, we are able to understand the influence of introducing substituents in the 4′-phenyl ring and compare the packing in the structures with that of the previously reported 4′-phenyl-2,2′:6′,2″-terpyridine (1). On going from 1 to 3, face-to-face π-stacking of pairs of 3-fluoro-5-methylphenyl rings contributes to a change in packing from a herringbone assembly in 1 with no ring π-stacking to a layer-like packing. The latter arises through a combination of π-stacking of aromatic rings and N…H⁻C hydrogen bonding. On going from 3 to 5, N…H⁻C and F…H⁻C hydrogen-bonding is dominant, supplemented by π-stacking interactions between pairs of pyridine rings. A comparison of the packing of molecules of 6 with that in 1, 3 and 5 is difficult because of the incorporation of solvent in 6·EtOH
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4 functionalized 2 2 6 2 Terpyridines as the nˆn domain in ir cˆn 2 nˆn pf6 complexes
Journal of Organometallic Chemistry, 2016Co-Authors: Daniel P Ris, Edwin C Constable, Gabriel E Schneider, Cathrin D Ertl, Emanuel Kohler, Thomas Muntener, Markus Neuburger, Catherine E. HousecroftAbstract:Abstract The cyclometallated iridium(III) complexes [Ir(ppy)2(NˆN)][PF6] (Hppy = 2-phenylpyridine) with NˆN = 4′-chloro-2,2′:6′,2″-terpyridine (1), 4′-methoxy-2,2′:6′,2″-terpyridine (2), 4′-ethoxy-2,2′:6′,2″-terpyridine (3), 4′-methylthio-2,2′:6′,2″-terpyridine (4), 4′-phenylthio-2,2′:6′,2″-terpyridine (5) and 4′-dimethylamino-2,2′:6′,2″-terpyridine (6) are reported including the single crystal structures of 2{[Ir(ppy)2(1)][PF6]}·0.6Et2O·CH2Cl2, [Ir(ppy)2(5)][PF6]·0.5CH2Cl2 and [Ir(ppy)2(6)][PF6]. The single crystal structure of [Ir(ppy)2(3)]Cl·2H2O·MeCN is also reported. In each complex, the 2,2′:6′,2″-terpyridine (tpy) ligand binds to the metal centre in a bidentate fashion with the non-coordinated pyridine ring folded into the coordination sphere and engaging in a pyridine–phenyl π-stacking interaction. Solution NMR spectra are consistent with hindered rotation of the non-coordinated pyridine ring at 298 K, with intra-cation CH…N(pyridine) hydrogen bond formation between adjacent [ppy]– and tpy ligands. Trends in the electrochemical HOMO–LUMO gaps and emission maxima of the complexes (in CH2Cl2 solution) are consistent with the electron-withdrawing or releasing properties of the 4′-tpy substituent; in degassed solution, [Ir(ppy)2(6)][PF6] has a quantum yield of 24.8% and emission lifetime of 441 ns, while the other complexes exhibit significantly lower quantum yields and shorter lifetimes.
Valery N Kozhevnikov - One of the best experts on this subject based on the ideXlab platform.
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mesomorphism and photophysics of some metallomesogens based on hexasubstituted 2 2 6 2 Terpyridines
Chemistry: A European Journal, 2016Co-Authors: N Saleesh S Kumar, Valery N Kozhevnikov, Adrian C Whitwood, Marsel Z Shafikov, Bertrand Donnio, Peter B Karadakov, Duncan W BruceAbstract:The luminescent and mesomorphic properties of a series of metal complexes based on hexacatenar 2,2′:6′,2′′-Terpyridines are investigated using experimental methods and density functional theory (DFT). Two types of ligand are examined, namely 5,5′′-di(3,4,5-trialkoxyphenyl)terpyridine with or without a fused cyclopentene ring on each pyridine and their complexes were prepared with the following transition metals: ZnII, CoIII, RhIII, IrIII, EuIII and DyIII. The exact geometry of some of these complexes was determined by single X-ray diffraction. All complexes with long alkyl chains were found to be liquid crystalline, which property was induced on complexation. The liquid-crystalline behaviour of the complexes was studied by polarising optical microscopy and small-angle X-ray diffraction. Some of the transition metal complexes (for example, those with ZnII and IrIII) are luminescent in solution, the solid state and the mesophase; their photophysical properties were studied both experimentally and using DFT methods (M06-2X and B3LYP).
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liquid crystalline Terpyridines
Chemical Communications, 2007Co-Authors: Valery N Kozhevnikov, Adrian C Whitwood, Duncan W BruceAbstract:5,5"-Disubstitution of the terpyridine core leads to the first inherently liquid-crystalline Terpyridines. Mesophases characteristic of bent-core and calamitic systems may be obtained depending on the core structure employed.
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an efficient route to 5 5 diaryl 2 2 6 2 Terpyridines through 2 6 bis 1 2 4 triazin 3 yl pyridines
Tetrahedron Letters, 2005Co-Authors: Valery N Kozhevnikov, Dmitry N Kozhevnikov, Olga V Shabunina, Vladimir L Rusinov, O N ChupakhinAbstract:Abstract A new route to substituted 2,2′:6′,2″-Terpyridines based on a new method for the synthesis of substituted 2,6-bis(1,2,4-triazin-3-yl)pyridines and their inverse electron demand Diels–Alder reaction is shown to be an efficient strategy for the synthesis of structurally diverse terpyridine ligands.
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a versatile strategy for the synthesis of functionalized 2 2 bi and 2 2 6 2 Terpyridines via their 1 2 4 triazine analogues
Journal of Organic Chemistry, 2003Co-Authors: Valery N Kozhevnikov, Dmitry N Kozhevnikov, Vladimir L Rusinov, O N Chupakhin, Tatiana V Nikitina, Manfred Zabel, Burkhard KonigAbstract:A general synthetic route for the synthesis of functionalized bi- and Terpyridines is reported. Functionalized 1,2,4-triazene 4-oxides 7 and 8-obtained from the reaction of hydrazones 1 with pyridine aldehydes and followed by oxidation-are functionalized by introduction of a cyano group via nucleophilic aromatic substitution. The thus-obtained 5-cyano-1,2,4-triazines 9 and 10 undergo facile inverse-electron-demand Diels-Alder reactions with enamines and alkenes to yield functionalized bi- and Terpyridines, respectively. The substituent at position 6 of the 1,2,4-triazene 4-oxides must be aromatic or heteroaromatic in order to allow their facile synthesis, but other substituents and reagents may vary. Each step of the synthetic route allows diversification, which makes the approach particularly useful for the facile synthesis of a large variety of functionalized bi- and Terpyridines.
