- Efficient and regioselective access to bis-heterocycles via palladium- catalysed coupling of organostannanes and organozincates derived from C-6 lithiated 2-methoxypyridine
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The efficient and regioselective synthesis of various bis-heterocyclic compounds was performed using a regioselective one-pot lithiation- transmetallation-cross-coupling of 2-methoxypyridine.
- Gros, Philippe,Fort, Yves
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- Platinum(II), palladium(II) and gold(III) adducts and cyclometalated derivatives of 6-methoxy-2,2′-bipyridine: A comparative study
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Reaction of 6-methoxy-2,2′-bipyridine (bpy6OMe) with the electron-rich platinum(II) complex [Pt(Me)2(DMSO)2] gave the rollover cyclometalated complex [Pt(κ2-N,C-bpy6OMe-H) (Me) (DMSO)] under mild conditions. The occurrence of rollover cyclometalation was demonstrated by single crystal X-ray diffraction structure determination. In contrast, reaction of bpy6OMewith [Pt(Ph)2(DMSO)2] and [Pt(Cl)2(DMSO)2] under mild conditions gave only adduct species of the type [Pt(X)2(bpy6OMe)] (X = Ph, Cl). Under harsher conditions, activation of a C-H bond in the methoxy substituent yielded the terdentate cyclometalated complex [Pt (κ3-N,N,C-bpy6OMe-H)Cl]. Finally, reaction of Pd(II) and Au(III) derivatives invariably gave adduct species, with the exception of the dimeric complex [Pd(κ2-N,C-bpy6OMe-H) (OAc)]2, which, however, was not isolated in pure form. The reactivity of bpy6OMe, as emerged from this study, was compared with that of the corresponding disubstituted ligand 6,6′-dimethoxy-2,2′-bipyridine, previously studied by us.
- Maidich, Luca,Cinellu, Maria Agostina,Cocco, Fabio,Stoccoro, Sergio,Sedda, Mondina,Galli, Simona,Zucca, Antonio
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- Stabilization and destabilization of the Ru-CO bond during the 2,2′-bipyridin-6-onato (bpyO)-localized redox reaction of [Ru(terpy)(bpyO)(CO)](PF6)
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Two stereoisomers of [Ru(terpy)(bpyO)(CO)](PF6)([1]+ and [2]+; terpy = 2,2′:6′,2″-terpyridine, bpyO = 2,2′-bipyridin-6-onato) were prepared. The pyridonato moiety in the bpyO ligand of [1]+ and [2]+ is located trans and cis, respectively, to CO. Treatment of [1]+ and [2]+ with HPF6 produced [1H]2+ and [2H]2+, both of which contain bpyOH (bpyOH = 6-hydroxy-2,2′-bipyridine). The difference in the pKa values of [1H]2+ (3.5) and [2H]2+ (3.9) reflects the stronger electronic interaction between CO and the pyridonato moiety in the bpyO ligand in the trans position compared with that in the cis position. The molecular structures of [1](PF6), [2](PF 6)·H2O and [2H](PF6)2· 2H2O were determined by X-ray structure analyses. [1]+ and [2]+ undergo one, reversible reduction at E1/2 = -1.65 V and -1.51 V, respectively, and one irreversible reduction at Ep,c = -2.07 and Ep,c = -2.13 V, respectively. Both reductions are assigned to redox reactions localized at the terpy and bpyO ligands. Irreversible reduction of [1]0 results from reductive cleavage of the Ru-CO bond of [1]-. On the other hand, a two-electron oxidation of [2] - almost regenerates [2]+ because of the depression of the reductive Ru-CO bond cleavage of [2]- due to cyclometalation formed by an attack of oxygen of bpyO to the carbon of the Ru-CO bond. An unusually large shift of the ν(C≡O) band on going from [2]0 (1950 cm-1) to [2]- (1587 cm-1) also supports a reversible cyclometalation driven by the bpyO-localized redox reaction. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Tomon, Takashi,Koizumi, Take-Aki,Tanaka, Koji
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- Rhodium(iii)-catalyzed switchable C-H acylmethylation and annulation of 2,2′-bipyridine derivatives with sulfoxonium ylides
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A novel protocol for Rh(iii)-catalyzed switchable C-H acylmethylation and annulation of 2,2′-bipyridine derivatives with sulfoxonium ylides is reported. This protocol provides a facile approach to synthesize structurally diverse acylmethylated 2,2′-bipyridine derivatives and acyl pyrido[2,3-a]indolizines with a broad range of functional group tolerance.
- Chen, Chen,Chen, Mengjia,Meng, Haifang,Wang, Yani,Yang, Fang,Zhu, Bolin
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supporting information
p. 4268 - 4271
(2021/05/31)
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- New Access Routes to Privileged and Chiral Ligands for Transition-Metal Catalyzed Hydrogen Autotransfer (Borrowing Hydrogen), Dehydrogenative Condensation, and Alkene Isomerization Reactions
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A group of transition-metal catalyzed hydrogen moving reactions, encompassing hydrogen autotransfer (HAT; also called borrowing hydrogen, BH), dehydrogenative condensation (DHC) and alkene isomerization, displays high atom economy and relies on widely ava
- Hintermann, Lukas,Jandl, Christian,Klein, Philippe,Koller, Sebastian,Ochmann, Lukas,P?thig, Alexander,Reinhardt, Katja,Seitz, Antonia
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- A novel approach for rhodium(iii)-catalyzed C-H functionalization of 2,2′-bipyridine derivatives with alkynes: A significant substituent effect
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We described a novel approach for the C-H functionalization of 2,2′-bipyridine derivatives with alkynes. DFT calculations and experimental data showed a significant substituent effect at the 6-position of 2,2′-bipyridine, which weakened the adjacent N-Rh bond and provided the possibility of subsequent rollover cyclometalation, C-H activation, and functionalization.
- Wu, Shaonan,Wang, Zhuo,Bao, Yinwei,Chen, Chen,Liu, Kun,Zhu, Bolin
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supporting information
p. 4408 - 4411
(2020/05/05)
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- Synthesis of Pyridylsulfonium Salts and Their Application in the Formation of Functionalized Bipyridines
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An S-selective arylation of pyridylsulfides with good functional group tolerance was developed. To demonstrate synthetic utility, the resulting pyridylsulfonium salts were used in a scalable transition-metal-free coupling protocol, yielding functionalized bipyridines with extensive functional group tolerance. This modular methodology permits selective introduction of functional groups from commercially available pyridyl halides, furnishing symmetrical and unsymmetrical 2,2′- A nd 2,3′-bipyridines. Iterative application of the methodology enabled the synthesis of a functionalized terpyridine with three different pyridine components.
- Duong, Vincent K.,Horan, Alexandra M.,McGarrigle, Eoghan M.
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p. 8451 - 8457
(2020/11/12)
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- Structural and Synthetic Insights into Pyridine Homocouplings Mediated by a β-Diketiminato Magnesium Amide Complex
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The reaction of [(DippNacnac)Mg(TMP)] (1) with 4-subtituted pyridines proceeds via sequential regioselective metallation and 1,2-addition to furnish a range of symmetric 4,4′-R2-2,2′-bipyridines in good yield, representing a new entry into bipyridine synthesis. Interestingly, the reaction of 1 with 2-OMe-pyridine led to formation of asymmetric bipyridine 6, resulting from the C6-magnesiation of the heterocycle followed by a C?C coupling step by addition to the C2 position of a second, non-metallated molecule, and subsequent elimination of [DippNacnacMgOMe]2 (7). Synthesis combined with spectroscopic and structural analysis help rationalise the underlying processes resulting in the observed reactivity, and elucidate the key role that the sterically encumbered β-diketiminate ligand plays in determining regioselectivity.
- Davin, Laia,Clegg, William,Kennedy, Alan R.,Probert, Michael R.,McLellan, Ross,Hevia, Eva
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supporting information
p. 14830 - 14835
(2018/09/25)
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- [Cu(P^P)(N^N)][PF6] compounds with bis(phosphane) and 6-alkoxy, 6-alkylthio, 6-phenyloxy and 6-phenylthio-substituted 2,2′-bipyridine ligands for light-emitting electrochemical cells
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We report a series of [Cu(P^P)(N^N)][PF6] complexes with P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) and N^N = 6-methoxy-2,2′-bipyridine (MeObpy), 6-ethoxy-2,2′-bipyridine (EtObpy), 6-phenyloxy-2,2′-bipyridine (PhObpy), 6-methylthio-2,2′-bipyridine (MeSbpy), 6-ethylthio-2,2′-bipyridine (EtSbpy) and 6-phenylthio-2,2′-bipyridine (PhSbpy). The single crystal structures of all twelve compounds have been determined and confirm chelating modes for each N^N and P^P ligand, and a distorted tetrahedral geometry for copper(i). For the xantphos-containing complexes, the asymmetrical bpy ligand is arranged with the 6-substituent lying over the xanthene ‘bowl'. The compounds have been characterized in solution by1H,13C and31P NMR spectroscopies, and their photophysical and electrochemical properties are described. They are yellow emitters and solid samples show photoluminescence quantum yields in the range up to 38%, with emission lifetimes ≤10.2 μs. On going from powder to frozen Me-THF, the excited state lifetimes increase which might suggest the presence of thermally activated delayed fluorescence (TADF). All the compounds have been tested in light-emitting electrochemical cells (LECs). Bright and stable LECs are obtained with complexes containing alkoxy- or phenyloxy-substituted ligands, making this family of compounds very relevant for the future development of copper-based electroluminescent devices.
- Alkan-Zambada, Murat,Keller, Sarah,Martínez-Sarti, Laura,Prescimone, Alessandro,Junquera-Hernández, José M.,Constable, Edwin C.,Bolink, Henk J.,Sessolo, Michele,Ortí, Enrique,Housecroft, Catherine E.
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supporting information
p. 8460 - 8471
(2018/08/21)
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- Csp2-Br bond activation of Br-pyridine by neophylpalladacycle: Formation of binuclear seven-membered palladacycle and bipyridine species
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In this work, the synthesis and reactivity of seven-membered palladacycles are described, and a novel bi-pyridine synthesis in a catalytic pathway is reported. Neophyl-palladacycle(i) reacts with an excess of 2-Br-pyridine, giving the desired new binuclear seven-membered palladacycle (1) and unexpectedly, a bipyridine complex, [Pd(BiPy)Br2]. ESI-HRMS experiments show that fragmentation of the Pd-Br bond in 1 can take place producing unusual two coordinated Pd(ii) molecular ions, [Pd(NeoPyR)]+.
- Nicasio-Collazo, Juan,Wrobel, Katarzyna,Wrobel, Kazimierz,Serrano, Oracio
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supporting information
p. 8729 - 8733
(2017/08/29)
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- Pyridine sulfinates as general nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions with aryl halides
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Pyridine rings are ubiquitous in drug molecules; however, the pre-eminent reaction used to form carbon-carbon bonds in the pharmaceutical industry, the Suzuki-Miyaura cross-coupling reaction, often fails when applied to these structures. This phenomenon is most pronounced in 2-substituted pyridines, and results from the difficulty in preparing, the poor stability of, and low efficiency in reactions of pyridine-2-boronates. We demonstrate that by replacing these boronates with pyridine-2-sulfinates, a cross-coupling process of unrivalled scope and utility is realized. The corresponding 3-And 4-substituted pyridine variants are also efficient coupling partners. In addition, we apply these sulfinates in a library format to the preparation of medicinally relevant derivatives of the drugs varenicline (Chantix) and mepyramine (Anthisan).
- Markovic, Tim,Rocke, Benjamin N.,Blakemore, David C.,Mascitti, Vincent,Willis, Michael C.
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p. 4437 - 4442
(2017/07/11)
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- Phosphine-Free Suzuki Cross-Coupling Reaction Using an Efficient and Reusable Pd Catalyst in an Aqueous Medium under Microwave Irradiation
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We report here an improved, highly efficient, and general method for the ligand-free Suzuki cross-coupling reaction to the synthesis of biaryls, bipyridyls, thienylpyridine, and allylphenols. Microwave irradiation of (het)aryl halides and (hetaryl, allyl)arylboronic acid N-methyl-iminodiacetic acid (MIDA) ester, using polyurea microencapsulated palladium catalyst (Pd EnCat 30), gave the coupling adducts 1a-x in excellent yields in just 10-18 min.
- Da Silva, Joaquim F. M.,Yepes Perez, Andres F.,De Almeida, Natália P.
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supporting information
p. 1995 - 2004
(2015/08/18)
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- An efficient and new protocol for phosphine-free Suzuki coupling reaction using palladium-encapsulated and air-stable MIDA boronates in an aqueous medium
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A simple methodology that uses a system based on polyurea microencapsulated palladium (PdEnCat 30) and aryl or (2-pyridyl) MIDA boronates for Suzuki-Miyaura cross-coupling reactions of (hetero)aryl halides in water-alcohol under phosphine-free conditions was developed. This journal is the Partner Organisations 2014.
- Mendes Da Silva, Joaquim Fernando,Yepes Perez, Andres Felipe,Pinto De Almeida, Natalia
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p. 28148 - 28155
(2014/07/21)
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- Palladacycle-catalyzed Suzuki-Miyaura reaction of aryl/heteroaryl halides with MIDA boronates in EtOH/H2O or H2O
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With good to excellent yields, a series of mono- or diheteroaryl compounds were synthesized via the palladacycle-catalyzed Suzuki-Miyaura reaction of various N-methyliminodiacetic acid (MIDA) boronates with aryl/heteroaryl halides in EtOH/H2O or H2O. This journal is the Partner Organisations 2014.
- Li, Yabo,Wang, Jingran,Wang, Zhiwei,Huang, Mengmeng,Yan, Beiqi,Cui, Xiuling,Wu, Yusheng,Wu, Yangjie
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p. 36262 - 36266
(2014/11/08)
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- Reductive couplings of 2-halopyridines without external ligand: Phosphine-free nickel-catalyzed synthesis of symmetrical and unsymmetrical 2,2'-bipyridines
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An unexpectedly facile synthetic approach for symmetrical and unsymmetrical 2,2'-bipyridines through the Ni-catalyzed reductive couplings of 2-halopyridines was developed. The couplings were efficiently catalyzed by 5 mol % of NiCl2.6H2O without the use of external ligands. A variety of 2,2'-bipyridines including caerulomycin F have been efficiently synthesized.
- Liao, Lian-Yan,Kong, Xing-Rui,Duan, Xin-Fang
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p. 777 - 782
(2014/04/03)
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- Tetrabutylammonium 2-pyridyltriolborate salts for Suzuki-Miyaura cross-coupling reactions with aryl chlorides
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Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of tetrabutylammonium 2-pyridyltriolborate salts with various aryl (heteroaryl) chlorides can produce the corresponding desired coupling products with good to excellent yields. These tetrabutylammonium salts are more reactive than the corresponding lithium salts. The coupling reactions with aryl chlorides progressed in the presence of PdCl2dcpp (3 mol %) and CuI/MeNHCH 2CH2OH (20 mol %) in anhydrous DMF without bases.
- Sakashita, Shohei,Takizawa, Miho,Sugai, Juugaku,Ito, Hajime,Yamamoto, Yasunori
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supporting information
p. 4308 - 4311
(2013/09/24)
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- Synthesis, characterisation and application of iridium(III) photosensitisers for catalytic water reduction
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The synthesis of novel, monocationic iridium(III) photosensitisers (Ir-PSs) with the general formula [IrIII(C^N)2(N^N)]+ (C^N: cyclometallating phenylpyridine ligand, N^N: neutral bidentate ligand) is described. The structures obtained were examined by cyclic voltammetry, UV/Vis and photoluminescence spectroscopy and X-ray analysis. All iridium complexes were tested for their ability as photosensitisers to promote homogeneously catalysed hydrogen generation from water. In the presence of [HNEt 3][HFe3(CO)11] as a water-reduction catalyst (WRC) and triethylamine as a sacrificial reductant (SR), seven of the new iridium complexes showed activity. [Ir(6-iPr-bpy)(ppy)2]PF 6 (bpy: 2,2′-bipyridine, ppy: 2-phenylpyridine) turned out to be the most efficient photosensitiser. This complex was also tested in combination with other WRCs based on rhodium, platinum, cobalt and manganese. In all cases, significant hydrogen evolution took place. Maximum turnover numbers of 4550 for this Ir-PS and 2770 for the Fe WRC generated in situ from [HNEt 3][HFe3(CO)11] and tris[3,5- bis(trifluoromethyl)phenyl]phosphine was obtained. These are the highest overall efficiencies for any Ir/Fe water-reduction system reported to date. The incident photon to hydrogen yield reaches 16.4 % with the best system. Copyright
- Gaertner, Felix,Cozzula, Daniela,Losse, Sebastian,Boddien, Albert,Anilkumar, Gopinatan,Junge, Henrik,Schulz, Thomas,Marquet, Nicolas,Spannenberg, Anke,Gladiali, Serafino,Beller, Matthias
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body text
p. 6998 - 7006
(2011/07/29)
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- Palladium(0)-catalysed cross-coupling of 2-trimethylsilylpyridine with aryl halides
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A general method for the Hiyama coupling reaction between aryl halides and 2-trimethylsilylpyridine has been developed. These conditions have been successfully applied to the synthesis of bis-heteroaryl systems, a key disconnection for the pharmaceutical industry in the synthesis of drug-like molecules.
- Blakemore, David C.,Marples, Louise A.
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supporting information; experimental part
p. 4192 - 4195
(2011/09/19)
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- Synthesis of 2,2-Bipyridines via Suzuki-Miyaura Cross-Coupling
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For a long time, the Suzuki-Miyaura cross-coupling reaction could not be used for the synthesis of 2,2′-bipyridines due to the lack of sufficiently stable 2-pyridylboron compounds. Stabilized 2-pyridylboronic acid esters recently developed by Hodgson, however, were found to be ideally suited for this purpose. Two general protocols could be developed and demonstrated to be valuable alternatives, which can be used very efficiently for the synthesis of functionalized 2,2-bipyridines.
- Guetz, Christoph,Luetzen, Arne
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experimental part
p. 85 - 90
(2010/04/29)
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- 2-Pyridyl and 3-pyridylzinc bromides: direct preparation and coupling reaction
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A facile synthetic approach to the direct preparation of 2-pyridyl and 3-pyridylzinc bromides has been demonstrated using Rieke zinc with 2-bromopyridine and 3-bromopyridine, respectively. A variety of different electrophiles have been coupled with the resulting organozinc reagents to give the corresponding cross-coupling products in moderate to good yields.
- Kim, Seung-Hoi,Rieke, Reuben D.
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scheme or table
p. 3135 - 3146
(2010/06/13)
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- Homoleptic zincate-promoted room-temperature halogen-metal exchange of bromopyridines
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Homoleptic lithium tri- and tetraalkyl zincates were reacted with a set of bromopyridines. Efficient and chemoselective bromine-metal exchanges were realized at room temperature with a substoichiometric amount of nBu 4ZnLi2·TMEDA reagent (1/3 equiv; TMEDA=N,N,N′,N′-tetramethylethylenediamine). This reactivity contrasted with that of tBu4ZnLi2·TMEDA, which was inefficient below one equivalent. DFT calculations allowed us to rationalize the formation of N...Li stabilized polypyridyl zincates in the reaction. The one-pot difunctionalization of dibromopyridines was also realized using the reagent stoichiometrically. The direct creation of C-Zn bonds in bromopyridines enabled us to perform efficient Negishi-type cross-couplings. Mild zincation! nBu4ZnLi2·TMEDA (in substoichiometric amounts) promoted efficient and chemoselective room-temperature bromine-metal exchange of a range of bromopyridines (see scheme). DFT calculations strongly supported the formation of a stabilized tripyridylzincate, which could be reacted with electrophiles or be directly involved in palladium-catalyzed cross-coupling reactions.
- Chau, Nguyet Trang Thanh,Meyer, Maxime,Komagawa, Shinsuke,Chevallier, Floris,Fort, Yves,Uchiyama, Masanobu,Mongin, Florence,Gros, Philippe C.
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experimental part
p. 12425 - 12433
(2011/01/05)
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- A facile synthetic route for 2-pyridyl derivatives: direct preparation of a stable 2-pyridylzinc bromide and its copper-free and pd-catalyzed coupling reactions
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Direct preparation of 2-pyridylzinc bromide has been developed. Interestingly, the subsequent coupling reactions with acid chlorides have been carried out without any transition metal catalyst. 2-Pyridylaryl compounds, symmetrical and unsymmetrical 2,2′-b
- Kim, Seung-Hoi,Rieke, Reuben D.
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supporting information; experimental part
p. 5329 - 5331
(2009/12/06)
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- Direct synthesis of unsymmetrical bis-heterocycles from 2-heterosubstituted 6-lithiopyridines
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Unsymmetrical bis-heteroaromatic compounds have been synthesized by nucleophilic coupling of C-6 lithiated 2-heterosubstituted pyridines with various heterocycles.
- Gros, Philippe,Fort, Yves
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p. 3515 - 3516
(2007/10/03)
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