CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• , consequently resulting in higher yields indifferently of the substrate. Enol acetates as another type of masked enol(ates) also proved to be appropriate substrates to access α-trifluoromethylated ketones (Scheme 3) [10]. In the presence of 1 mol % of (4,4'-di-tert-butyl-2,2'-bipyridine)bis[(2-pyridinyl)phenyl

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• stoichiometric amounts of oxidant and further transformation of the azotrifluoromethyl products allowed a Fisher indole synthesis. From a mechanistic point of view, the excited photocatalyst was oxidised by the aryldiazonium salt to produce [Ru(bpy)3]3+ (bpy: 2,2’-bipyridine) as the oxidant to generate the CF3

• authors also realised the same chemical transformation under visible light irradiation at 450 nm by means of the iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 ([4,4’-bis(tert-butyl)-2,2’-bipyridine]bis[3,5-difluoro-2-[5-(trifluoromethyl)-2-pyridinyl]phenyl]iridium(III) hexafluorophosphate), which

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

• Andrea Porcheddu,
• Evelina Colacino,
• Giancarlo Cravotto,
• Francesco Delogu and
• Lidia De Luca

Beilstein J. Org. Chem. 2017, 13, 2049–2055, doi:10.3762/bjoc.13.202

• first stage [Cu(MeCN)4]OTf (5 mol %), 2,2′-bipyridine (5 mol %), NMI (10 mol %), and TEMPO (5 mol %) were milled (1 min) in a stainless steel reactor using four stainless steel balls of different sizes. Following the mechanical treatment, the catalyst uniformly covered the reactor walls forming a dark

• of [Cu(MeCN)4]OTf, 2,2′-bipyridine and TEMPO to 3 mol % and NMI loading to 7 mol % without affecting the reaction time or the product yield. Interestingly, the alcohol-to-aldehyde oxidation under ball milling conditions was faster (15 min overall) than that in solution (1 h) [25]. In addition, the

Chemoselective synthesis of diaryl disulfides via a visible light-mediated coupling of arenediazonium tetrafluoroborates and CS₂

• Jing Leng,
• Shi-Meng Wang and
• Hua-Li Qin

Beilstein J. Org. Chem. 2017, 13, 903–909, doi:10.3762/bjoc.13.91

• reactions [15][22]. Based on the above research results, we envisioned that a radical pathway may facilitate the formation of diaryl disulfides. Therefore the photocatalyst Ru(bpy)3(PF6)2 (bpy = 2,2’-bipyridine) [23] and a 20 W blue-light LED were chosen as catalyst and the source of visible light

• . Ru(bpy)3Cl2 catalyzed this coupling to afford the desired product 3a in a moderate yield of 65% (Table 3, entry 8). However, when the iridium-based photocatalysts Ir(ppy)3 [24], [Ir(ppy)2(bpy)]PF6 and [Ir(ppy)2(dtbbpy)]PF6 (bpy = 2,2’-bipyridine, ppy = 2-phenylpyridine, dtbbpy = 4,4’-di-tert-butyl

• -2,2’-bipyridine) [25][26] were used, the product yield of diphenyl disulfide (3a) was much lower compared to reactions performed in the presence of ruthenium catalysts (Table 3, entries 9–11). A plausible reaction mechanism has been proposed and is depicted in Scheme 2. We envision that the phenyl

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• that a N,N-bidentate ligand, 2,2’-bipyridine (L5) could prompt the conversion of aryl halides to phenols in the presence of KOH as coupling partner (Scheme 8) [30]. Aryl iodides and electron-deficient aryl bromides were easily converted to the corresponding phenols in good to excellent yields. A broad

• hydroxylation of hydroxylation of aryl halides. MCM-41-dzt-Pd catalyzed hydroxylation of aryl halides. Hydroxylation of aryl halides using dibenzoylmethane as ligand. Hydroxylation of aryl halides using 2,2’-bipyridine as ligand. Hydroxylation of aryl bromides using imidazolyl pyridine as ligand. Hydroxylation

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• singlet oxygen. Photooxygenation of N-methyl-1,2,3,6-tetrahydrophthalimide and reductive work-up to alcohol 3a. Oxidation of N-methyl-1,2,3,6-tetrahydro-3-acetamidophthalimide and reductive work-up to alcohol 3b. Molar attenuation coefficients of common photosensitizersa (bpy = 2,2‘-bipyridine

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• or O-nonaflation led to functionalized pyridine derivatives. Scheme 1 illustrates this sequence with the synthesis of two 2,2´-bipyridine derivatives 4a or 5b that were obtained by employing picolinic acid chloride for the N-acylations followed by O-methylation with methyl iodide or by O-nonaflation

• have to conclude that this approach to β-ketoenamides is not efficient. With N-pyridyl-substituted β-ketoenamides 3a–h in hand, we investigated their cyclocondensations to the corresponding 2,2´-bipyridine derivatives 5a–h (Table 1). As in our preliminary experiments the use of trimethylsilyl

• of the cyclocondensation step and subjected the unpurified compounds to the O-nonaflation procedure. Treatment with an excess of sodium hydride in THF followed by reaction with nonafluorobutanesulfonyl fluoride (NfF) afforded the desired 2,2´-bipyridine derivatives 5a–g containing the 4-nonafloxy

Chiral Cu(II)-catalyzed enantioselective β-borylation of α,β-unsaturated nitriles in water

• Lei Zhu,
• Taku Kitanosono,
• Pengyu Xu and
• Shū Kobayashi

Beilstein J. Org. Chem. 2015, 11, 2007–2011, doi:10.3762/bjoc.11.217

• -unsaturated nitriles in water. The catalyst system, which consisted of Cu(OAc)2 and a chiral 2,2′-bipyridine ligand, enabled β-borylation and chiral induction in water. Subsequent protonation, which was accelerated in aqueous medium, led to high activity of this asymmetric catalysis. Both solid and liquid

• chiral 2,2′-bipyridine ligand L for 1 h. After successive addition of cinnamonitrile (1a) and bis(pinacolato)diboron, the resulting mixture was stirred at room temperature for 12 h. Subsequent oxidation by treatment with NaBO3 was conducted to determine the enantioselectivity. The desired β

• formed with chiral 2,2′-bipyridine ligand L constitutes a green and efficient catalyst for asymmetric boron conjugate addition of α,β-unsaturated nitriles in water. Both aromatic and aliphatic α,β-unsaturated nitriles were applicable, and both gave the corresponding chiral β-hydroxynitriles after

Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines

• Ya Lin Tnay,
• Gim Yean Ang and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209

• additive 1,10-phenanthroline to 40 mol % slightly improved the yield, giving 3a in 40% yield (Table 1, entry 1). The use of 2,2’-bipyridine (bpy) provided a comparable result (Table 1, entry 2), while performing the reaction in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) led to lower yields of

The simple production of nonsymmetric quaterpyridines through Kröhnke pyridine synthesis

• Isabelle Sasaki,
• Jean-Claude Daran and
• Gérard Commenges

Beilstein J. Org. Chem. 2015, 11, 1781–1785, doi:10.3762/bjoc.11.193

• is easily introduced on the 2,2’-bipyridine or 2,2’:6’,2”:6”-terpyridine moieties [31][32]. In fact, the use of a chiral enone (i.e., (−)-myrtenal) led to the chiral 5,6-substituted quaterpyridine 8. The corresponding platinum complex 9 was obtained by a classical synthesis, which entails the

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• attention of synthetic chemists. Liu and co-workers [166] have constructed the [10]paracyclophane 208 (skeleton of hirsutellones) via RCM. The 2,2’-bipyridine unit is an interesting building block due to its use in chelating ligands, as a binding agent and also a useful template in supramolecular chemistry

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

• Christian Benkhäuser and
• Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

• Christian Benkhauser Arne Lutzen Kekulé-Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany 10.3762/bjoc.11.79 Abstract A Tröger's base-derived racemic bis(1,10-phenanthroline) ligand (rac)-1 and a bis(2,2'-bipyridine) ligand with a

• alkyne 11 in 96% yield [28]. Finally, a two-fold Sonogashira reaction with 1,3-diiodobenzene afforded the desired bis(2,2’-bipyridine) ligand 2 in quantitative yield. Metal coordination After the successful synthesis we prepared a DMSO solution of copper(I) ions, added it to the ligands (rac)-1 and 2

• form and a bis(2,2'-bipyridine) ligand 2. Upon coordination to copper(I) ions none of these ligands alone self-assembles into discrete homoleptic oligonuclear metallosupramolecular aggregates. When mixed in an equimolar ratio, however, these ligands undergo highly selective self-assembly into

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• ] [Cp*Rh(bpy)(H2O)]Cl2 [aquo(2,2’-bipyridine)(pentamethylcyclopentadienyl)]rhodium(III), where Cp* = pentamethylcyclopentadienyl. For comparison we have also used its iridium analog, with phenantroline as a bidentate N-ligand replacing bpy. Iridium showed interesting activity, comparable to that of Rh

Molecular ordering at electrified interfaces: Template and potential effects

• Thanh Hai Phan and
• Klaus Wandelt

Beilstein J. Org. Chem. 2014, 10, 2243–2254, doi:10.3762/bjoc.10.233

• distances have also been observed for π–π stacked phases of 2,2'-bipyridine on Au(111) [28] and Cu(111) [26]. Even though this distance is typical for π–π-interacting aromats [29], the measured distance of 0.36 nm agrees perfectly with the separation between parallel densely packed rows of chloride anions

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• an initial photoredox electron transfer that we considered in analogy to the Barton–McCombie technology to be crucial to trigger deoxygenations. Initial deoxygenation experiments were carried out with either Ru(bpy)3Cl2·6H2O [bpy = 2,2'-bipyridine] or [Ir(ppy)2(dtb-bpy)](PF6) [ppy = 2-phenylpyridine

• ; dtb-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine] as photocatalysts, Hantzsch ester (diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate) as hydrogen donor, and iPr2NEt as sacrificial electron donor in DMF (Scheme 3). Light generated from a high power LED was channeled into the reaction solution in

Direct C–H trifluoromethylation of di- and trisubstituted alkenes by photoredox catalysis

• Ren Tomita,
• Yusuke Yasu,
• Takashi Koike and
• Munetaka Akita

Beilstein J. Org. Chem. 2014, 10, 1099–1106, doi:10.3762/bjoc.10.108

• –CF3 bonds is highly demanded. Results: The photoredox reaction of alkenes with 5-(trifluoromethyl)dibenzo[b,d]thiophenium tetrafluoroborate, Umemoto’s reagent, as a CF3 source in the presence of [Ru(bpy)3]2+ catalyst (bpy = 2,2’-bipyridine) under visible light irradiation without any additive afforded

• ]2+ (bpy: 2,2’-bipyridine)), the relevant Ir cyclometalated complexes (e.g., fac-Ir(ppy)3 (ppy: 2-phenylpyridine)) and organic dyes has been developed; the trifluoromethyl radical (·CF3) can be easily generated from conventional CF3 radical precursors such as CF3I, CF3SO2Cl and CF3SO2Na through

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic α,β-unsaturated carbonyl compounds

• Dominik Lenhart and
• Thorsten Bach

Beilstein J. Org. Chem. 2014, 10, 890–896, doi:10.3762/bjoc.10.86

• = phenylpyridyl; bpy = 2,2’-bipyridine) and [Ir(ppy)2(dtbbpy)]BF4 (7) (dtbbpy = 4,4’-di-tert-butyl-2,2’-bipyridine) gave the best results while other iridium catalysts turned out to be inferior. Remarkably, the desired tricyclic product 10 was isolated as the only product while the direct addition product 11 was

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• states using metal ions (not coordinated: anti, coordinated: syn) and was not used in our work for this reason. Some time ago we developed a series of 2,2’-bipyridine-based allosteric analogues [20][21][22] of the well-known resorcinarene-based hemicarcerands [23][24]. However, these possess only rather

• bipyridine structure to potentially affect the binding of another substrate. Rhenium(I), on the other hand, obviously prefers coordination to nitrogen compared to sulfur as we could demonstrate by coordinating 4,4’-dithioisocyanato-2,2’-bipyridine (14) to it. Figure 1 shows the molecular structure of this

• thermodynamically stable binding ligand. In this way one can make sure that just one single other chelating ligand like a 2,2’-bipyridine can be bound to this metal complex fragment. Sterically hindered 1,10-phenanthrolines and their copper(I) complexes have been proven to be perfectly suited for this purpose [21

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• additives, Fokin and Finn have presented 2,2’-bipyridine and 1,10-phenanthroline derivatives as effective ligands for CuAAC reactions with copper(II) sulfate and sodium ascorbate (Figure 2) [84]. A two- to three-fold increase in the rate of reaction was observed with this class of ligands

• quantities (ligand:metal ratio > 2:1), the reaction is dramatically slowed down or does not work at all. As the rigid chelating ligands of this class bind so strongly to copper(I) ions, they form inhibitory species. Catalysis is usually shut down completely when an excess of 2,2’-bipyridine or 1,10

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• ]. The complex [Pt(Me)(OTf)(dbbipy)] C3 (dbbipy = 4,4'-di-tert-butyl-2,2'-bipyridine) was prepared by treatment of [PtCl(Me)(dbbipy)] with AgOTf [49]. Regarding tridentate ligands, the X-ray structure of the triflate complex [Pt(3,3'-iPr2-BQA)(OTf)] C4b (BQA = bis(8-quinolinyl)amine) shows a coordinated

Copper-catalyzed aerobic aliphatic C–H oxygenation with hydroperoxides

• Pei Chui Too,
• Ya Lin Tnay and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2013, 9, 1217–1225, doi:10.3762/bjoc.9.138

• presence of Et3N (2 equiv) in DMF, the reaction proceeded at room temperature for 17 h to afford C–H oxygenation products, cyclic hemiacetal 2a and 1,4-diol 3a in 49% and 8% yields, respectively (Table 1, entry 1). It was found that addition of nitrogen ligands such as 2,2’-bipyridine and 1,10

Aqueous reductive amination using a dendritic metal catalyst in a dialysis bag

• Jorgen S. Willemsen,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 960–965, doi:10.3762/bjoc.9.110

• ). The first step involved demethylation of 4,4’-dimethoxy-2,2’-bipyridine (1) in 92% yield [31]. Monofunctionalization of the ligand will lead to the highest possible catalyst loading per dendrimer and also prevents cross-linking between dendrimers. Therefore, a 1:1 mixture of isopropyl mesylate (5) and

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

• ] complexes, among them the classical complexes with 1,10-phenanthroline (phen) and 2,2'-bipyridine (bipy) as bisdentate diimine ligands, which were among the first SCO compounds of iron(II) reported in the literature [14][15]. An example of [FeN6] complexes with trisdentate N-donor ligands is bis[hydro-tris

• based on the cationic LS [Fe(2,2”-bipyridine)3]2+ or [Fe(2,2":2',6'-terpyridine)2]2+ ions, where the critical field strength to reach the crossover condition is fulfilled by introducing sterically hindering groups adjacent to the donor atoms or by replacing the pyridine rings by five-membered

• heterocycles [25][26]. Examples are the SCO systems tris(6-methyl-2,2'-bipyridine)iron(II) and bis(2,4-bis(pyridin-2-yl)thiazole)iron(II) ions [49]. The [FeN6] system can also exhibit SCO behavior when six monodentate N-donating ligand molecules are involved. The best known examples are the [Fe(N-alkyl

Synthesis of new pyrrole–pyridine-based ligands using an in situ Suzuki coupling method

• Matthias Böttger,
• Björn Wiegmann,
• Steffen Schaumburg,
• Peter G. Jones,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2012, 8, 1037–1047, doi:10.3762/bjoc.8.116

• , Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.8.116 Abstract The compounds 6-(pyrrol-2-yl)-2,2‘-bipyridine, 2-(pyrrol-2-yl)-1,10-phenanthroline and 2-(2-(N-methylbenz[d,e]imidazole)-6-(pyrrol-2-yl)-pyridine were synthesized by using an in situ generated boronic

• substructures of common neutral ligands used in europium complex chemistry [6][9]: 2,2’-bipyridine and 1,10-phenanthroline. Compound 3 comprises a benzimidazole heterocycle, which was also used by the Bünzli group [1][2][3][4]. The synthesis of the resulting complexes was to date unsuccessful. We report here on

• Centre as supplementary publications no. CCDC-871428 (1), CCDC-871429 (2·CH3OH), CCDC-871430 (3·C2H5OH). Copies of the data can be obtained free of charge from http://www.ccdc.cam.ac.uk/data_request/cif. Synthesis and characterization of the heteroaryl bromides 8 and 9 starting from 2,2’-bipyridine (11

Toward unidirectional switches: 2-(2-Hydroxyphenyl)pyridine and 2-(2-methoxyphenyl)pyridine derivatives as pH-triggered pivots

• Christina Tepper and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2012, 8, 977–985, doi:10.3762/bjoc.8.110

• , is the 2,2′-bipyridine unit [32][34][35]. Rotation around the C–C bond that connects the two pyridine units is induced by the addition of a metal salt, which leads to the corresponding metal complexes. The back rotation is caused by the removal of the metal ion by the addition of cyclam, which