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

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

• hydrogen bond N17–H17…N1 involving the peripheral rings, which connects the molecules via the a-glide plane to form chains parallel to the a-axis. The structure of the methanol solvate of compound 2 is shown in Figure 3. The 1,10-phenanthroline ring system is planar (mean deviation 0.01 Å), and the pyrrole

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• of the π-linker, particularly in chromophores 53–57, caused β enhancement up to 320 × 10−30 esu (Table 8). This clearly demonstrates the beneficial role of the thiophene as a polarizable unit and auxiliary electron donor. A combination of fused phenanthroline-imidazole acceptor moiety, N,N

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• arylation of heterocycles, including electron-rich azoles with aryl bromides, by using potassium phosphate as a base and phenanthroline as a ligand (Scheme 8) [47]. Over the past few decades, it has also been demonstrated that copper catalysis is not required in order to attain good yield and selectivity in

• -formylthiophene by using Cu(I) cocatalyst and 1,10-phenanthroline in DMA solvent (Scheme 31a) [82]. This year, Oliaf studied more specifically the palladium- and copper-catalyzed oxidative C–H/C–H cross-coupling of various electron-rich 1,3-diazoles and reported notably the direct coupling of benzothiazole with

Impact of the level of complexity in self-sorting: Fabrication of a supramolecular scalene triangle

• Kingsuk Mahata and
• Michael Schmittel

Beilstein J. Org. Chem. 2011, 7, 1555–1561, doi:10.3762/bjoc.7.183

• various scalene triangles. It turned out that the self-sorting system with a higher level of complexity was far superior to less complex sorting algorithms. Keywords: copper; metallosupramolecular chemistry; phenanthroline; self-assembly; self-sorting; Introduction Self-assembly guided by self-sorting

• -coupling reactions [15]. A known procedure was followed to prepare the terpyridine–phenanthroline hybrid 7 [8]. The lengths of the ligands were chosen in such a way that they provide the geometrically different sides of a scalene triangle. Results and Discussion We tested both self-sorting algorithms as

• purification. The 1H NMR spectrum was found to be broad (Figure 3a). The broadening of the signals is partly due to the presence of a phenanthroline–Cu+–terpyridine complex. Due to the tetrahedral coordination behaviour of Cu+, one pyridine nitrogen atom of the terpyridine unit is left uncoordinated [30], and

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

• under mild conditions. In this reaction CuCl (20 mol %) with 1,10-phenanthroline (10 mol %) and bipyridine (10 mol %) was used as the catalyst. It is interesting to observe that the use of the mixed ligands is important for the higher yields of this transformation: With the monoligand approach developed

• (1a) with O2 based on the pioneering study of oxidation of normal simple alcohols by Markó et al. [12]. Under the original conditions [12], the expected allenylic ketone 2a was obtained in 59% yield when CuCl and 1,10-phenanthroline were used (Table 1, entry 1). A series of bases and solvents were

• 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

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• achieved, all reactions required elevated reaction temperatures (≥ 80 °C) and, in most cases, high catalyst loadings (up to 20%). However, the results were greatly improved for the 1,10-phenanthroline (phen) systems 29/MnCl2 and 32/MnCl2 – MnCl2 is added to remove the phen-ligand by precipitation of MnCl2

• expense of higher catalyst loadings (10 mol %) and elevated reaction temperatures. In contrast, the phenanthroline–alkylidyne system 32 requires higher temperatures (80 °C) only for the activation with MnCl2, whereas the metathesis reaction can be carried out at ambient temperature. Noteworthy, it is the

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• , was achieved by reacting 9-N-purines 91 with an excess of arylboronic acid 92 in the presence of copper(II) acetate, molecular sieves and phenanthroline (Scheme 22). Bakkestuen and Gundersen showed that electron-donating and electron-withdrawing substituents on the arylboronic acid were tolerated

• , reaction temperatures (90–115 °C) and reaction times (48 h) are comparable to the palladium-catalysed processes. Ligand-free and ligand-assisted reaction conditions have been applied in the synthesis of biologically active compounds. DMEDA, proline and phenanthroline are the most commonly used ligands. In

Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

• Monika Mazik and
• André Hartmann

Beilstein J. Org. Chem. 2010, 6, No. 9, doi:10.3762/bjoc.6.9

• observed for 4 and 5 are quite different to those of the recently described phenanthroline/aminopyridine-based receptors 22 and 23 (see Figure 4) [27][29], which show a strong preference for α-glucoside and α-galactoside vs. the β-anomers. Thus, depending on the nature of the recognition units used as

• structure. In contrast to 4 and 5, the previously described phenanthroline/aminopyridine-based receptors 22 and 23 were shown to display a high binding affinity towards α-galactoside as well as a strong α- vs. β-anomer binding preference. Thus, depending on the nature of the recognition units incorporated

• -glucose [3], b) Amaranthus caudatus agglutinin with Galβ3GalNAc [1]. Structures of receptors 1–5. Structures of sugars investigated in this study. Structures of the recently described phenanthroline/aminopyridine-based receptors showing α- vs. β-anomer binding preferences in the recognition of glycosides