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

• spirodienone 3a (Table 1, entry 3). We therefore decided to proceed with 1,10-phenanthroline as the optimal ligand and subsequently tested different Cu(II) and Cu(I) salts (Table 1, entries 4–7). The best results were obtained using 40 mol % CuI which provided 3a in 46% isolated yield (Table 1, entry 7). A

Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• displaying the typical octahedral geometry. The reaction of [RuL1(CH3CN)4](PF6)2 with triphenylphosphine and 1,10-phenanthroline resulted in the substitution of one and two coordinated acetonitrile ligands and afforded [RuL1(PPh3)(CH3CN)3](PF6)2 (4) and [RuL1(phen)(CH3CN)2](PF6)2 (5), respectively. The

• complexes show good catalytic activity in the transfer hydrogenation of ketones. The reaction of acetonitrile-coordinated Ru–NHC complex 2 with other donors such as triphenylphosphine and 1,10-phenanthroline was also studied. Results and Discussion Synthesis and characterization of [Ru(L1)2(CH3CN)2](PF6)2

• triphenylphosphine and 1,10-phenanthroline The coordinated acetonitrile ligands could be easily replaced by various N- and P-donors [22]. The reactions of the acetonitrile-coordinated Ru–NHC complexes with other ligands were studied. The reaction of complex 2 with an excess of triphenylphosphine and 1,10

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• 70% overall yield. The synthesis started with 4-bromo-1,10-phenanthroline subjected to an oxidative cleavage with potassium permanganate to afford binicotinic acid. The binicotinic acid product was esterified using dicyclohexylcarbodiimide (DCC) in methanol and the resulting ester was cross-coupled

• ) has been performed by Lotter and Bracher [67]. The route included four steps, but unfortunately, the overall yield was only 7%. Like in method A, the synthesis started with 1,10-phenanthroline to prepare binicotinic acid via oxidative cleavage by potassium permanganate. The esterification took place

• decarboxylated to give kynuramine (65). The latter, by reaction with dopamine, forms the benzo-3,6-phenanthroline intermediate 68, which in turn gave shermilamine B (67) upon reaction with cysteine (Figure 8) [76]. The compounds 13-didemethylaminocycloshermilamine D (31) and demethyldeoxyamphimedine (9) (Figure

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

• without putting a considerable amount of steric strain into the aggregate. In the search for ligand structures that fulfill these requirements we came up with ligands 1 and 2 that are depicted in Figure 1. Ligand 1 has a very rigid twisted V-shaped structure that presents its phenanthroline units in a way

• . Scheme 5 summarizes the coordination behavior of the two ligands 1 and 2 and their mixture towards copper(I) ions. Conclusion In summary, we have synthesized two concave or V-shaped multivalent ligands − a dissymmetric bis(phenanthroline) ligand (rac)-1 based on the Tröger's base scaffold in its racemic

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Copper-promoted hydration and annulation of 2-fluorophenylacetylene derivatives: from alkynes to benzo[b]furans and benzo[b]thiophenes

• Yibiao Li,
• Liang Cheng,
• Xiaohang Liu,
• Bin Li and
• Ning Sun

Beilstein J. Org. Chem. 2014, 10, 2886–2891, doi:10.3762/bjoc.10.305

• product (Table 1, entry 1). The usage of CuCl and 1,10-phenanthroline (1,10-phen) as a ligand in CH3CN at 80 °C showed that 2a could be isolated in 35% yield (Table 1, entry 2). The screening of the various solvents revealed that the solvent played an important role in this hydration and annulation

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

• phenanthroline did not improve the yield to appreciable extent, thus the Rh-complex was used. Other photomaterials which are active upon visible light irradiation were also tested, such as Fe/ZnS, Co/ZnS, Ag/ZnS, ZnBiO4, AgVO4, NiO, CrF3@TiO2, tiron@TiO2. However, they did not show significant activity in the

• green precipitate was obtained, isolated and analyzed, resulting in the title compound. Synthesis of [Cp*Rh(bpy)H2O]Cl2 [Cp*Rh(bpy)H2O]Cl2 was obtained from [Cp*RhCl2]2 as reported in [29]. Phenanthroline was used instead of bpy to generate [Cp*Rh(phen)(H2O)]Cl2. The analogous Ir complex was prepared

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

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

• ][32][33][34][35]. Thus, we chose to prepare 2,9-bis[2,6-dimethoxyphenyl]-1,10-phenanthroline (22) as such a sterically congested ligand (Scheme 6) [36]. 22 was synthesised starting from 1,10-phenanthroline via N,N'-dialkylation to dibromide 23 in very good yield [37]. Oxidation of 23 with potassium

• )]PF6, and [Zn(22)(1)](OTf)2 as evidenced by MALDI mass spectrometry and NMR spectroscopy (Figure 6 and Figure 7). Hence, zinc(II) ions or their complexes with a single, sterically demanding phenanthroline ligand like 22 as well as a similar [Cu(22)]+ complex were all found to be good effectors for

• metal-to-ligand-to-substrate assemblies. Zinc(II) or copper(I) phenanthroline complexes with sterically very demanding phenanthrolines were found to be effective to achieve a 1:1 effector–receptor stoichiometry. This makes these ligands promising candidates that could act as potential allosteric

Copper–phenanthroline catalysts for regioselective synthesis of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and of pyrrolo[1,2-a]phenanthrolines under mild conditions

• Rupankar Paira,
• Tarique Anwar,
• Maitreyee Banerjee,
• Yogesh P. Bharitkar,
• Shyamal Mondal,
• Sandip Kundu,
• Abhijit Hazra,
• Prakas R. Maulik and
• Nirup B. Mondal

Beilstein J. Org. Chem. 2014, 10, 692–700, doi:10.3762/bjoc.10.62

• -700032, India 10.3762/bjoc.10.62 Abstract A new series of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and pyrrolo[1,2-a]phenanthrolines were efficiently built up from an 8-hydroxyquinoline derivative or phenanthroline via 1,3-dipolar cycloaddition reaction involving non-stabilized

• azomethine ylides, generated in situ from the parent furo[3,2-h]quinoliniums/phenanthroliums, in presence of a copper(II) chloride–phenanthroline catalytic system. The methodology combines general applicability with high yields. Keywords: copper(II) chloride–phenanthroline; 1,3-dipolar cycloaddition; furo

• after an extensive screening, we found copper(II) chloride–phenanthroline as the best catalytic pair for this purpose. Herein we wish to present the results of our recent synthetic efforts to synthesize a series of unique pentacyclic pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines using

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• electronpoor 1,10-phenanthroline as ligands was published [32], however, in our hands no favorable effect on the isolated yields of 2a was found (Table 1, entries 4–8). The cyclization works equally well with conductive heating in an oil bath instead of microwave heating (Table 1, entry 8). At higher

Cu-Mediated trifluoromethylation of benzyl, allyl and propargyl methanesulfonates with TMSCF₃

• Xueliang Jiang and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2013, 9, 2862–2865, doi:10.3762/bjoc.9.322

• Ar atmosphere. However, only 17% yield of the desired product 2a was observed in this case (Table 1, entry 1). The yield was improved to 31% when the reaction was carried out in the presence of 1,10-phenanthroline (phen) (Table 1, entry 2). Increasing the substrate concentration (from 0.1 M to 0.4 M

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

• -phenanthroline derivatives is present in the reaction mixture [80]. Although the structural characteristics of the corresponding copper complexes remain elusive, these ligands are frequently applied in CuAAC reactions, especially in macromolecular chemistry [15]. Apart from N-donor ligands, the use of phosphorus

• toluene proceeds within 40 minutes at room temperature to give 96% yield. Under neat conditions, the amount of catalyst can be lowered to 50 ppm and the reaction still gives 81% yield after 24 hours [142]. Recently, it has been shown that the phenanthroline complex [Cu(phen)(PPh3)2]NO3 outperforms their

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• 1,10-phenanthroline and KF respectively [73]. In addition to activating the silyl group of the trifluoromethylating agent, the silver salt also acts as a stabilizer for the CF3− species and prevents its self-decomposition (Figure 4). As a result, the more economical TMSCF3 can be employed, and good

• convenient sources of trifluoromethyl anion [75]. H. Amii et al. reported on the use of an O-silylated hemiaminal as a cross-coupling partner for aromatic trifluoromethylation with a copper iodide/1,10-phenanthroline catalytic system [76]. Compound B was prepared from commercially available hemiacetal of

• base and an oxidant. The reaction conditions had to be slightly customized for each class of substrates. The methodology was first developed for 2-substituted 1,3,4-oxadiazoles (Cu(OAc)2/1,10-phenanthroline/t-BuONa/NaOAc/air, Table 20), then extended to benzo[d]oxazoles, benzo[d]imidazoles, benzo[d

Cu-catalyzed trifluoromethylation of aryl iodides with trifluoromethylzinc reagent prepared in situ from trifluoromethyl iodide

• Yuzo Nakamura,
• Motohiro Fujiu,
• Tatsuya Murase,
• Yoshimitsu Itoh,
• Hiroki Serizawa,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2013, 9, 2404–2409, doi:10.3762/bjoc.9.277

• reaction are summarized in Table 1. After Zn(CF3)I was prepared in situ by the treatment of CF3I (ca. 5 equiv) with Zn dust (2 equiv) [22] in various solvents at room temperature for 2 hours, the reactions were explored by adding a catalytic amount of copper(I) salt and 1,10-phenanthroline (phen) [18][19

• 1,10-phenanthroline. Further studies on highly efficient trifluoromethylation and difluoromethylation reactions with trifluoromethylzinc reagents are under way. Experimental Typical procedure for copper-catalyzed trifluoromethylation of aryl iodide To the suspension of zinc powder (without activation

• -phenanthroline (1.8 mg, 0.01 mmol, 2 mol %), and then aryl iodide 1a (138.0 mg, 0.5 mmol) were added. The reaction mixture was stirred at 50 °C for 24 h. After cooling to room temperature, the yield of product 2a was determined by 19F NMR analysis by using benzotrifluoride (BTF) as an internal standard. Except

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• instead of DTBP reduced the yield to only 38% (Table 1, entry 2). With the help of 1,10-phenanthroline (30 mol %) as the ligand, the yield could be slightly improved to 68% (Table 1, entry 3). Iron(III) acetylacetonate provided a superior yield (91%) compared to the other Fe salts such as FeCl3, ferrocene

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

• ) and solvent (S17) forms [53]. Energetically accessible T-shaped species can also be intermediates in the site exchange of bidentate ligands of square-planar complexes. Fluxional motions of the 2,9-dimethyl-1,10-phenanthroline ligand (dmphen) have been observed in cationic complexes as [Pt(Me)(NN)(L

• -phenanthroline ligand is used. Interestingly, the mechanism can be switchable between associative and dissociative [107][108][109]. For the latter scenario, 14-electron T-shaped species involving phosphine ligands can be envisaged as feasible intermediates. The dissociative pathway fully prevails when

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• hydrocarbons, Xu and co-workers developed other redox initiators in addition to the NHPI/quinone systems previously described. In 2005 they reported the selective oxygenation of ethylbenzene to the corresponding acetophenone by means of a NHPI/o-phenanthroline-mediated organocatalytic system, in the presence

• of molecular bromine as a co-catalyst [68] (Scheme 24). According to the proposed mechanism, Br2 generates ET processes by oxidizing the o-phenanthroline to the corresponding cation radicals. The latter promote in turn ET and HAT processes with NHPI, leading to the formation of PINO. In 2009 the same

• from N-alkoxyphthalimides. Visible-light/g-C3N4 induced metal-free oxidation of allylic substrates. NHPI/o-phenanthroline-mediated organocatalytic system. NHPI/DMG-mediated organocatalytic system. NHPI catalyzed oxidative cleavage of C=C bonds. Synthesis of hydrazine derivatives. Acknowledgements We

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

• could be trapped by O2 to form the new C–O bonds. Herein, we report the realization of this concept mainly for the aerobic synthesis of 1,4-diols from hydroperoxides, which could be catalyzed by the Cu(OAc)2-1,10-phenanthroline system in the presence of Et3N as a terminal reductant of the Cu(II) species

• -phenanthroline (1,10-phen) accelerated the reaction (Table 1, entries 2 and 3). The reactions with CuCl2 (Table 1, entry 4) as well as CuCl (Table 1, entry 5) resulted in comparable results with that by Cu(OAc)2. Further optimization of the reaction conditions by the solvent screening (Table 1, entries 6–11

Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes

• Amaresh Mishra,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2013, 9, 866–876, doi:10.3762/bjoc.9.100

• )2]2+ complex (Δλem = 41 nm) compared to the parent [Ru(tpy)2]2+ (see Table 1) [48]. Recently, Andvincula et al. also reported a large red-shift (Δλem = 165 nm) of the 3MLCT emission for the ruthenium(II)-cored phenanthroline-oligothiophene dendrimer compared to the parent phenanthroline complex [51

Efficient Cu-catalyzed base-free C–S coupling under conventional and microwave heating. A simple access to S-heterocycles and sulfides

• Silvia M. Soria-Castro and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2013, 9, 467–475, doi:10.3762/bjoc.9.50

• of inexpensive potassium thioacetate with both electron-rich and electron-poor aryl iodides under a base-free copper/ligand catalytic system. CuI as copper source affords S-aryl thioacetates in good to excellent yields, by using 1,10-phenanthroline as a ligand in toluene at 100 °C after 24 h. Under

• . More recently, S-aryl thioacetates have been obtained by the catalyst system [Pd2(dba)3-Xantphos] in 1,4-dioxane under microwave heating at 160 °C in good yields [51]. The synthesis of arylthiobenzoates by a CuI/1,10-phenanthroline, starting from thiobenzoic acid and iPr2NEt (DIPEA) in toluene after 24

• Initially, we tried PhCOSH with PhI using the catalytic systems of CuI/1,10-phenanthroline in toluene according to the method described by Sawada [52]. This methodology proved particularly sensitive to the nature and concentration of the base used in the deprotonation of the phenyl thiobenzoic acid due to

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

• after the discovery of thermal ST by Cambi et al. the first iron(II) coordination compound, viz. [Fe(phen)2(NCS)2] (phen = 1,10-phenanthroline), was observed to show also thermally induced ST between HS and LS states: the spin transition takes place very abruptly near to 175 K [14][15]. Since then, many

• ] 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

• highest pressure applied, the HS (S = 2) state has entirely been suppressed in the room-temperature region (Figure 9). Figure 10 shows the results of a pressure-effect study on [Fe(phy)2](BF4)2 (phy = 1, 10-phenanthroline-2-carbaldehydephenylhydrazone) [167]. This system exhibits hysteresis during the

Intramolecular carbolithiation of N-allyl-ynamides: an efficient entry to 1,4-dihydropyridines and pyridines – application to a formal synthesis of sarizotan

• Wafa Gati,
• Mohamed M. Rammah,
• Mohamed B. Rammah and
• Gwilherm Evano

Beilstein J. Org. Chem. 2012, 8, 2214–2222, doi:10.3762/bjoc.8.250

• nucleophiles. By using a slightly modified Hsung’s procedure, a series of N-allyl-ynamides 1 could be readily prepared in acceptable yields using a combination of copper(II) sulfate pentahydrate (40 mol %) and 1,10-phenanthroline (80 mol %) with potassium phosphate in refluxing toluene, the major side reaction

C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation

• Zhenhua Ding and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2012, 8, 1536–1542, doi:10.3762/bjoc.8.174

• pyrimidyl group functions as a readily removable directing group [34]. We also reported an ortho-alkylation reaction of aromatic imines with vinylsilanes and simple olefins using a cobalt–phenanthroline catalyst (Scheme 1b) [35]. Building on these studies, we have developed a cobalt–bathocuproine catalyst

• -phenanthroline (phen, 10 mol %) and neopentylmagnesium bromide (100 mol %), which was effective for ortho-alkylation of aromatic imines [35], afforded the desired adduct 3aa in only 17% yield accompanied by a small amount of a C2-neopentylated product 4 (Table 1, entry 1). Subsequent examination of

• phenanthroline and bipyridine-type ligands (Table 1, entries 2–5) revealed that 2,9-dimethyl-1,10-phenanthroline (neocuproine) and 2,9-dimethyl-4,7-diphenylphenanthroline (bathocuproine) improved the yield of 3aa, while the byproduct 4 could not be suppressed (Table 1, entries 3 and 4). The P,N-bidentate ligand

Organocatalytic C–H activation reactions

• Subhas Chandra Pan

Beilstein J. Org. Chem. 2012, 8, 1374–1384, doi:10.3762/bjoc.8.159

• under the same reaction conditions. Shi and co-workers reported a similar reaction with 1,10-phenanthroline as catalyst at 100 °C employing aryl iodides and aryl bromides as the substrates [34]. Whereas 40 mol % of the catalyst and 3.0 equivalents of potassium tert-butoxide as base were needed for the