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

CuCl-catalyzed aerobic oxidation of 2,3-allenols to 1,2-allenic ketones with 1:1 combination of phenanthroline and bipyridine as ligands

• Shuxu Gao,
• Yu Liu and
• Shengming Ma

Beilstein J. Org. Chem. 2011, 7, 396–403, doi:10.3762/bjoc.7.51

• order to improve the yield further, we examined the effect of ligands. When 2,2'-bipyridine, which has a weaker coordinating ability, was used [36], the yield of 2a was lower (Table 3, entry 2). With 4,7-diphenyl-1,10-phenanthroline the yield was slightly improved to 66% (Table 3, entry 3). These

• , it was interesting to observe that when 4,7-diphenyl-1,10-phenanthroline and 2,2'-bipyridine were mixed in the ratio of 1:1 [37][38], the isolated yield was improved to 82% (Table 3, entry 6). The yield with 1,10-phenanthroline and 2,2'-bipyridine (1:1) was 83% (Table 3, entry 10). However, 4,7

• -diphenyl-1,10-phenanthroline is relatively expensive (1 g, $ 94, Aldrich), so the cheaper 1,10-phenanthroline (5 g, $ 26.4, Aldrich) was used for further study. The effect of ratio of 1,10-phenanthroline vs 2,2'-bipyridine on the yield was also studied: A ratio of 1:1 proved to be the best (Table 3

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• complex [RuCl2(=CHPh)(SIMes)(PCy3)], CuCl, and dHbipy (SIMes is 1,3-dimesitylimidazolin-2-ylidene, dHbipy is 4,4'-di-n-heptyl-2,2'-bipyridine) was able to promote the ATRA of trichloroacetic acid onto cyclopentadiene followed by a lactonization into 3,3-dichloro-3,3a,4,6a-tetrahydro-2H-cyclopenta[b]furan

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• polymer dissolved in toluene. The synthesis of fluorescent conjugated particles of poly(arylene diethynylenes) in direct miniemulsions by Glaser coupling has also been reported [133]. 4,4'-Dinonyl-2,2'-bipyridine was found to be a suitable ligand for solubilizing the copper(I) chloride catalyst in the

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• functionality under the polymerization conditions [33]. The catalytic system employed in the synthesis is based on copper(I) bromide and 2,2´-bipyridine in a DMSO solution. After 24 h of stirring at ambient temperature, viscous, deep brown magnetic dispersions are obtained. The success of the surface-initiated

• solution (Fluka, 25%), Nα-benzoyl-D,L-arginin-4-nitroanilide hydrochloride (BAPNA) (Sigma, 98%), benzylamine (BzA) (Janssen Chimica), 2,2´-bipyridine (bpy) (Aldrich, 99%), citric acid monohydrate (Grüssing GmbH, 99,5%), (4-(chloromethyl)phenyl)trimethoxysilane (CPS) (ABCR, 95%), copper(I) bromide (CuBr

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• stationary phase for enantioseparation of racemic protonated primary arylalkyl amines [153]. Comparable enantioselectivities with a stronger co-ordinating ligand can be achieved using a crown ether bearing a bispyridyl (bpy) unit in the ring (23). A series of these C2-symmetric 2,2-bipyridine-containing

Size selective recognition of small esters by a negative allosteric hemicarcerand

• Holger Staats and
• Arne Lützen

Beilstein J. Org. Chem. 2010, 6, No. 10, doi:10.3762/bjoc.6.10

• Holger Staats Arne Lutzen University of Bonn, Kekulé-Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany 10.3762/bjoc.6.10 Abstract A bis(resorcinarene) substituted 2,2′-bipyridine was found to bind weakly to small esters like ethyl acetate whereas more

• resorcinarene moieties in different directions so that they cannot act cooperatively in the binding of the substrate. Keywords: allosteric receptors; 2,2′-bipyridine; hemicarcerand; molecular recognition; resorcin[4]arene; Introduction Nature uses allosteric effects in a very elegant manner to control

• 2,2′-bipyridine. This structure has proved to be an excellent allosteric centre [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] due to its well defined ability to switch between syn- and an anti-conformations [27]. Recently, we were able to synthesize a number of

Functional properties of metallomesogens modulated by molecular and supramolecular exotic arrangements

• Alessandra Crispini,
• Mauro Ghedini and
• Daniela Pucci

Beilstein J. Org. Chem. 2009, 5, No. 54, doi:10.3762/bjoc.5.54

• -mesogenic 4,4′-disubstituted 2,2′-bipyridine ligands with Pt(II) salts confirmed the role of coordination chemistry in the metal-mediated formation of liquid crystals. Indeed the induction of a dipole moment upon coordination with an MX2 moiety, allowed most of the half-disc shaped complexes [LnPtX2