Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• will focus our attention on recently reported Pt(II) complexes by breaking down the different classes into those containing monodentate, bidentate, tridentate and tetradentate chromophoric ligands, in order to put in context and compare their photophysical and electroluminescent properties. Finally

• doped films, OLED devices were fabricated showing remarkable efficiency attaining EQE of 21.5% at a luminance of 1029 cd m−2 with small roll-off [21]. These performances are the best reported so far for such a practical luminance. Systems based on bidentate ligands In the past, the most common synthetic

• strategy to obtain luminescent platinum(II) complexes has been the use of π-conjugated chelating ligands with a bidentate motif bearing π-accepting (hetero)aromatic units. Compared to monodentate ligands, the more rigid structure of the bidentate motif is expected to reduce excited-state molecular

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• selectivity of ortho-lithiation could be tuned by changing the alkyllithium reagent employed. The performance of four inherently chiral bidentate calix[4]arene ligands in the asymmetric Tsuji–Trost allylation reaction (Scheme 10) has been evaluated and compared to that of the planar model ligands. Inherently

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• -phenylbut-1-yne [119] tridentate tris(benzimidazole) ligands completely failed and tris(triazole) ligands gave only poor to moderate yields (16–65%) even at 100 °C, whereas all the bidentate ligands (phenanthrolines L1, L2 and diimidazo[1,2-a:2',1'-c]quinoxalines L3–L6) were found to be more efficient both

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

• Rebecca Pittkowski and
• Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

• challenging [7][8]. Tetradentate [9][10][11], terdentate [12][13][14][15], and bidentate [16][17][18][19][20] cyclometalated Pt(II) complexes were recently shown to be promising phosphorescent triplet emitters in OLEDs (PhOLEDs), which emit light with high quantum yields in the blue spectral region. The

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• enhancing its practicality. Comparative reactions were carried out to evaluate its catalytic activity in IEDDA reactions of diazine including phthalazine as well as 1,2,4,5-tetrazine. Keywords: air-stable catalyst; bidentate; bisboron; diazine; Diels–Alder; Lewis acid; Introduction The development of

• LUMOs are rather high in energy [9][10][11][12]. In the past years, we demonstrated a bisboron bidentate Lewis acid (Scheme 1, A) as an efficient catalyst for the IEDDA reaction of 1,2-diazines to access 1,2-substituted aromatics [13][14]. Additionally, we could incorporate this reactivity in domino

• -orbital of the boron atom. This may prevent the boron compound from decomposition as well as hydrolysis and provide a practical Lewis acid catalyst for organic reactions. To test the hypothesis, several Lewis bases were subjected to the coordination reaction with the bidentate bisboron catalyst, 5,10

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

• Kohsuke Aikawa,
• Kohei Yabuuchi,
• Kota Torii and
• Koichi Mikami

Beilstein J. Org. Chem. 2018, 14, 576–582, doi:10.3762/bjoc.14.44

• , CF2Br, and n-CnF2n+1 (n = 2, 3, 8) groups. Results and Discussion Our initial investigation was focused on the methylation of ethyl trifluoropyruvate (1a) with Me2Zn in the presence of a copper salt bearing a chiral bidentate phosphine ligand (Table 1). We were delighted to find that the reaction

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

• Irwan Iskandar Roslan,
• Kian-Hong Ng,
• Gaik-Khuan Chuah and
• Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

• silylation [72]. In these reactions, the single electron transfer (SET) is initiated by KOt-Bu/DMF [63][67][69][71] or KOt-Bu in combination with additives such as bidentate diamine ligands [61][62][63][64][65], 18-crown-6 [70] or azobisisobutyronitrile (AIBN) [62][66]. Herein, we report the synthesis of

Diastereoselective Mannich reactions of pseudo-C₂-symmetric glutarimide with activated imines

• Tatsuya Ishikawa,
• Tomoko Kawasaki-Takasuka,
• Toshio Kubota and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 2473–2477, doi:10.3762/bjoc.13.244

• unambiguously determined by X-ray crystallographic analysis (Figure 1) [16]. Based on this information a possible reaction mechanism was formulated as depicted in Scheme 1. It is well-known that oxazolidinone-derived imides in general construct bidentate chelation when they are converted to the corresponding

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

• Alexis Perry and
• Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

• ). The extension of this basic bidentate ligand with further substituents has been employed to generate structures with bespoke binding characteristics (e.g., metal ion specificity, control of complex stoichiometry, greater binding affinity) [17]. Typifying this approach, Natali et al. synthesised

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

• Kohei Yamada,
• Naoto Kamimura and
• Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

• Suzuki–Miyaura coupling between 5-(triazinyloxy)oxazole 3aa and phenylboronic acid (4a, Table 2). As expected, the desired trisubstituted oxazole 5aaa was obtained in 21% yield (Table 2, entry 1). The use of different bidentate (dppp) or monodentate (PCy3) phosphines as ligands for the Ni catalyst

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

• Desirée Leistenschneider,
• Nicolas Jäckel,
• Felix Hippauf,
• Volker Presser and
• Lars Borchardt

Beilstein J. Org. Chem. 2017, 13, 1332–1341, doi:10.3762/bjoc.13.130

• they are gradually consumed by the mechanically-induced polymerization. The spectrum of the Ti-containing polymer (Polymer-SF-3) displays the appearance of a band at 1558 cm−1, which corresponds to titanium, bidentate to a carboxylic group [50]. Additionally, the blue-shift of the vibration at 1703 cm

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

• catalysts. However, copper catalysts often have a low catalytic activity to activate the C–Hal bond. Fortunately, along with the development of various bidentate ligands, the copper-catalyzed C–O coupling reaction has been extensively applied in the synthesis of phenols from aryl halides. However, the

• combination of CuI and bidentate ligand could promote the conversion of aryl halides to the corresponding phenols in a mixed solvent system of DMSO/H2O (1:1). Using iodobenzene as model substrate, various ligands were successfully tested: L-proline (yield 70%), 2-hydroxyacetophenone (yield 85%), N,N-dimethyl

• 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

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

• Nikolay V. Lukashev,
• Gennadii A. Grabovyi,
• Dmitry A. Erzunov,
• Alexey V. Kazantsev,
• Gennadij V. Latyshev,
• Alexei D. Averin and
• Irina P. Beletskaya.

Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55

• anthraquinones. Further attempts to apply the Cu-based catalytic system in this reaction with L-proline and other commonly used N,N, N,O, and O,O bidentate ligands were fruitless. Previously, some of us successfully used the classic conditions of the Buchwald–Hartwig amination for the preparation of bis-amino

• with copper cation in comparison to bidentate ligands 5c and 5d. However, the cholane skeleton in 5c and 5d can be useful for integration of these ligands into lipophilic membranes. Conclusion Cu- and Pd-catalyzed cross-coupling reactions were applied for the preparation of arylamino derivatives of

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

• Yi Lai,
• Zhijian Zong,
• Yujie Tang,
• Weimin Mo,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen,
• Liqun Jin,
• Wen-hua Sun and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 213–221, doi:10.3762/bjoc.13.24

• ]. Alternatively, the palladacycles reported by Herrmann and Beller in the 1990s [30] effectively elongated the lifetime of the active Pd species through employing bidentate or multidentate ligands [31][32][33][34][35][36]. Meanwhile nitrogen ligands are also widely used for palladium catalysts in coupling

• reactions with the advantage of convenient synthetic methods, easy functional group modifications and better stability [37][38][39][40][41][42][43]. Pyridine, azole and imine-based N(sp2) ligands received considerable attention, especially bidentate N,N-ligands. In general, most bidentate N,N(sp2) ligands

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

• Ming Liu,
• Jan C. Namyslo,
• Martin Nieger,
• Mika Polamo and
• Andreas Schmidt

Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264

• , MICs) and vice versa [34]. Herein, conjugated mesomeric betaine 2-(1-butyl-1H-imidazolium-3-yl)phenolate, its tautomeric NHC and its anionic NHC are shown to serve as monodentate and bidentate ligands, respectively. Results and Discussion Salt 5 is available via a three-step procedure [35

• ), 6.72 ppm, and 5.81 ppm, respectively. Single crystals of [Rh(7)3] (11) were obtained by slow evaporation of a concentrated solution of 11 in a mixture of EtOAc and MeOH. The single crystal X-ray analysis proved that three anionic N-heterocyclic carbenes 7 serve as bidentate ligands, respectively

• –Ccarbene bonds have lengths between 184.06(19) pm and 184.82(19) pm, respectively. These values correspond to literature-known bond lengths of cis arranged bidentate ligands around Ni [42][43][44], but, as expected, they differ from those of [(PEt3)(Ph)Ni(imidazo[1,5-a]quinolin-9-olate-1-ylidene)] [45] as

Organometallic chemistry

• Bernd F. Straub,
• Rolf Gleiter,
• Claudia Meier and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 2216–2221, doi:10.3762/bjoc.12.213

• the very few chemists with a history of research and teaching in theoretical, organic and inorganic chemistry. His research interests combined all three fields, with a focus on homogeneous catalysis with transition metal complexes. Bidentate donor ligands with a small bite angle such as bis(di-tert

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• absorber; non-fullerene acceptor; zinc(II) complex; Introduction Azadipyrromethenes (ADPs) (Figure 1a) are a class of monoanionic bidentate ligands with strong absorption in the visible and near IR range. Their absorbance and emission properties can be readily tuned through structural modifications and

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• shown to occur by an associative mechanism via a trigonal bipyramidal intermediate [66][67], which was also crystallographically characterized in the case of a cationic Rh complex bearing a bidentate phosphine ligand [68]. Our DFT-calculations for the tricarbonyl complex 3a bearing the dipiy ligand show

A T-shape diphosphinoborane palladium(0) complex

• Patrick Steinhoff and
• Michael E. Tauchert

Beilstein J. Org. Chem. 2016, 12, 1573–1576, doi:10.3762/bjoc.12.152

• (CyDPBPh)Pd(0) 9, which was characterized by X-ray analysis. Keywords: ambiphilic ligand; coordination chemistry; diphosphinoborane; organometallics; palladium; Introduction The amplification of traditional bidentate chelating L2-type ligands with a tethered borane functionality (e.g., Bourissou’s

Ring-whizzing in polyene-PtL₂ complexes revisited

• Oluwakemi A. Oloba-Whenu,
• Thomas A. Albright and
• Chirine Soubra-Ghaoui

Beilstein J. Org. Chem. 2016, 12, 1410–1420, doi:10.3762/bjoc.12.135

• is Pt and a phosphine. The second method employs the use of a bidentate phosphine. In this regard we have chosen diphosphinylethane (dpe). This idea here is that the P–Pt–P angle is around 100° in polyene–ML2 complexes. Upon dissociation the 14 electron PtL2 complex strongly prefers to be linear [22

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• ) fragment in a bidentate fashion and undergoes a redox isomerization reaction wherein the carbinol proton performs a 1,2-hydride shift. The resulting vinylruthenium intermediate can be seen as a resonance structure of a ruthenium carbene, which coordinates to a pendant alkene, performs a [2 + 2

• , indicating that the tethered sulfoxide complex is much more efficient at catalyzing redox bicycloisomerization (Table 4, entry 2). As one would expect from the lessons learned in the previous studies, chiral bidentate (R)-BINAP completely inhibits any reactivity (Table 4, entry 3). Surprisingly, monodentate

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• corresponding products were found to have improved diastereoselectivities. Phenols with electron-withdrawing groups failed to afford the expected products under the same conditions. Mechanistically, Ga(OTf)3 may activate the allene and phenol substrates simultaneously via the bidentate model. In contrast, the

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• efficient platforms for bidentate coordination in metal catalysis and good precursors of carboxylic acids, ketones and aldehydes upon oxidative cleavage of the keto/diol moiety [72]. More recently, a comprehensive study on the first evidence of the utility of these acceptors in organocatalysis has been

Bi- and trinuclear copper(I) complexes of 1,2,3-triazole-tethered NHC ligands: synthesis, structure, and catalytic properties

• Shaojin Gu,
• Jiehao Du,
• Jingjing Huang,
• Huan Xia,
• Ling Yang,
• Weilin Xu and
• Chunxin Lu

Beilstein J. Org. Chem. 2016, 12, 863–873, doi:10.3762/bjoc.12.85

• precatalysts in the transfer semihydrogenation of alkynes to Z-alkenes. Messerle et al. [26] synthesized a series of new cationic Rh(I), Rh(III) and Ir(III) complexes containing hybrid bidentate N-heterocyclic carbene-1,2,3-triazolyl donors. We [27] have synthesized a series of nonsymmetrical pincer palladium

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

• Vladislav Vasilenko,
• Torsten Roth,
• Clemens K. Blasius,
• Sebastian N. Intorp,
• Hubert Wadepohl and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

• have a significant influence on the binding geometry und coordination properties of these bidentate P,N-donors. Keywords: P,N-ligands; phosphanylformamidines; phosphine imines; transition metal complexes; Introduction P,N-ligands have been applied in a wide variety of chemical reactions ranging from

• previous protocols was reversed, that means, the carbon–nitrogen bond was formed in the second step of the synthesis. Condensation of aldehyde 6 with mesitylamine gave ligand 7 in good yield [14][15][16]. The connectivity of the ligands 2, 3, 5 and 7 imposes a varying level of rigidity on these bidentate