Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• (Figure 2) [26][27]. In addition, 1-acyl-5-hydroxypyrazolines are bidentate ligands for zinc complexes and by virtue of being ring tautomers of β-enolhydrazones they can also act as tridentate ligands for nickel [28] and tin [29][30] complexes. In contrast, dimethylzinc forms dimeric complexes where the 1

• -acyl-5-hydroxypyrazoline acts as a bidentate ligand [31]. Upon treatment with TMEDA mononuclear complexes with concomitant ring opening to give a seven-membered bidentate chelate are generated. Although numerous syntheses of pyrazolines [3][4][5] in general and 1-acyl-5-hydroxypyrazolines [24][25][26

Design of a double-decker coordination cage revisited to make new cages and exemplify ligand isomerism

• Sagarika Samantray,
• Sreenivasulu Bandi and
• Dillip K. Chand

Beilstein J. Org. Chem. 2019, 15, 1129–1140, doi:10.3762/bjoc.15.109

• ]. Complexation of cis-protected palladium(II), i.e., (PdL’) or bare palladium(II) with non-chelating bidentate ligands is known to afford a series of (PdL’)mLm or PdmL2m-type self-assembled coordination complexes [5]. Pd2L4-type cages are the simplest representatives among the PdmL2m-type complexes, yet most

Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation

• Yang Liu,
• Julie Oble and
• Giovanni Poli

Beilstein J. Org. Chem. 2019, 15, 1107–1115, doi:10.3762/bjoc.15.107

• . The effect of the solvent was then assessed. While no reaction took place in CH3CN (Table 1, entry 3), DMF (Table 1, entry 4) and DMSO (Table 1, entry 5) allowed the formation of 4a in 66% and 75% yield, respectively. The use of another bidentate phosphine such as dppe gave no improvement (Table 1

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• alkyl chain is used (as in 8). These observations suggest that the herein synthesized bidentate analogues of GlcNAc would interact with WGA differently than compounds bearing one sugar residue. The short distance between the two sugar moieties as well as the presence of the non-polar alkyl chains seems

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• appropriate metal ion(s) and ligand(s) has been demonstrated in various reports [46][47][48][49]. In Figure 1, a comprehensive framework is shown in which nanoscale architectures are built from various monodentate (pyridine; Figure 1a), bidentate (bipyridine, phenanthroline; Figure 1b) and tridentate

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• bidentate ligands investigated by a number of research groups [5]. The pyridinyl alcohol found its way to the Grubbs-type complexes from research by Van Der Schaaf and co-workers on the Schrock-type analogues [6][7]. Grubbs 1-type complexes 3a–f (Figure 2) were used to catalyse the ring-closing metathesis

• an increase in IPs) indicates decomposition of the precatalyst to active isomerisation species, probably metal hydride species. In our NMR study no indication of the existence of metal hydride species was found. Conclusion The aim of our research is to control the Ru–N bond strength of the bidentate

• bidentate pyridinyl-alcoholato ligand by Me and OMe groups. We synthesised the 3-, 4-, and 5-methyl and 3-methoxy-substituted 5d precatalysts. The catalytic activity, selectivity and stability results of the Me- and OMe-substituted 5d precatalysts, in 1-octene metathesis, showed promising results at high

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• symmetrical counterparts fail or show poor efficiency [5][6]. Moreover, the use of catalysts incorporating bidentate unsymmetrical NHCs has allowed for significant enhancements in the field of both asymmetric and Z-selective olefin metathesis reactions [7][8][9]. The aim of the present review is to provide a

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• Pd sources, namely Pd(PPh3)4 or Pd(OAc)2 were used, the latter without the addition of any mono- or bidentate P-ligand. Although Et3N can usually be used successfully, the dealkylation of the phosphite reagent may occur. In order to avoid this unwanted side reaction, K2CO3 was also involved in

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• -phenanthroline) as the catalyst, 4a-Me was obtained in 86% yield after esterification. Other bidentate ligands such as bpy, phen, and dppe were not suitable for this reaction. Control experiments revealed that both the Co catalyst and the Mn reductant were indispensable to the reaction. The carboxylation of

• . reported that a Rh complex with a suitable bidentate ligand was an efficient catalyst for the [2 + 2 + 2] cycloaddition reaction (Scheme 39) [79]. The reaction of 43a was performed using 20 mol % [Rh(cod)2]BF4 and a bidentate phosphine in 1,2-dichloroethane at room temperature. Prior to the addition of 43a

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• the formation of the corresponding pincer complexes 17c and 17d directly without formation of an isolable bidentate intermediate observed during the synthesis of complexes 17a and 17b. Furthermore, the successful synthesis of the pincer complexes was confirmed by X-ray crystallography and the

• (93%, 80% and 75% for the 1st, 2nd and 3rd run, respectively) considering the fact that some of it could have been extracted along with the product and the results are summarised in Figure 5. Since the bidentate complexes 20a and 20b are also potential catalysts in their own right, the catalytic

• and complexes 17a–d. Proposed mechanism of the Suzuki–Miyaura coupling reaction using pincer complex 17d. Investigation on the reusability of the catalyst. Suzuki–Miyaura coupling reaction catalysed by the SN-bidentate complex 20a. Crystal data and structure refinement parameters for 17d. Optimization

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• cyclic diaryl-λ3-iodanes (Scheme 26) [66]. The palladium phosphine ligand plays a crucial role as a bidentate ligand with a bite angle greater than 100° such as DPEphos (104°) or Xantphos (108°) significantly improves the yields. The reaction applies to a series of anilines and aliphatic amines, but

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