Enantioselective synthesis of planar chiral ferrocenes via palladium-catalyzed annulation with diarylethynes

• Yan-Chao Shi,
• Rong-Fei Yang,
• De-Wei Gao and
• Shu-Li You

Beilstein J. Org. Chem. 2013, 9, 1891–1896, doi:10.3762/bjoc.9.222

• Road, BDA, Beijing, 100176, China 10.3762/bjoc.9.222 Abstract When Boc-L-Val-OH was used as a ligand for the enantioselective Pd(II)-catalyzed annulation of N,N-substituted aminomethyl ferrocene derivatives with diarylethynes, ferrocenes with planar chirality could be achieved with excellent

• enantioselectivity (up to 99% ee). Keywords: annulation; asymmetric catalysis; C–H activation; ferrocene; palladium; planar chirality; Introduction Chiral ferrocene derivatives have been widely applied to asymmetric catalysis, materials science, biomedical research, etc. [1][2][3][4]. Particularly, ferrocenes with

• ][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. Inspired by their works, we reported a direct arylation of ferrrocene with arylboronic acid to introduce planar chirality into the ferrocene backbone using N,N-dimethylaminomethyl as the directing group and Boc-L-Val-OH as the ligand

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

Efficient continuous-flow synthesis of novel 1,2,3-triazole-substituted β-aminocyclohexanecarboxylic acid derivatives with gram-scale production

• Sándor B. Ötvös,
• Ádám Georgiádes,
• István M. Mándity,
• Lóránd Kiss and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1508–1516, doi:10.3762/bjoc.9.172

• -aminocyclohexanecarboxylates 11–14 were prepared previously by a diastereoselective epoxidation of the corresponding 2-aminocyclohexenecarboxylates, followed by a regioselective oxirane ring opening with NaN3 [68]. Three different alkynes (phenylacetylene, diethyl acetylenedicarboxylate and ethynyl ferrocene) were employed as

• difference was observed between the performances of the two methods. Ferrocene-triazole conjugates play a crucial role in the labelling and detection of various systems, such as biomolecules, polymers, nanomaterials and supramolecular assemblies [70]. They also have potential applications in medicinal

• chemistry and drug discovery as biosensing probes, in immunoassays and in host–guest chemistry [71]. Ferrocene-substituted amino acids have been of significant importance in the investigation of the secondary structures of different peptides and foldamers [72]. Thus, conjugates of the azido-functionalized β

Linkage of α-cyclodextrin-terminated poly(dimethylsiloxanes) by inclusion of quasi bifunctional ferrocene

• Helmut Ritter,
• Berit Knudsen and
• Valerij Durnev

Beilstein J. Org. Chem. 2013, 9, 1278–1284, doi:10.3762/bjoc.9.144

• terminally substituted oligo(dimethylsiloxanes) bearing α-cyclodextrins (α-CD) as host end groups for the cyclopentadienyl rings of ferrocene. This double complexation of unsubstituted ferrocene leads to a supramolecuar formation of the siloxane strands. Structural characterization was performed by the use

• of 1H NMR and IR spectroscopy and by mass spectrometry. Electron microscopy studies and dynamic light scattering measurements show a significant decrease of the derivative size after the complexation with ferrocene. In addition, further evidence for the successful complexation of the end groups was

• verified by the shifts of the protons in the 1H NMR spectra and in the correlation signals of the 2D ROESY NMR spectra. Keywords: cyclodextrins; ferrocene; host–guest systems; polysiloxanes; supramolecular chemistry; Introduction Polymers containing cyclodextrins (CD) covalently or supramolecularly

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• −5.72 eV and the LUMO −2.74 eV with reference to ferrocene, which was used as an internal standard and has a HOMO of −4.8 eV. In comparison to the HOMO and LUMO values for T1 [14] (−5.6 and −2.2 eV) there is a decrease in the HOMO and a large decrease in the LUMO, with a reduction in the HOMO–LUMO gap

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• saturated calomel electrode-SCE). Ferrocene was used as a standard and the potentials were determined from half-peak potentials. The free energy change ΔGet for an electron-transfer reaction is calculated from the classical Rehm–Weller equation (Equation 1) [60] where Eox, Ered, ES and C are the oxidation

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

• platinum wire, and the reference electrode was an Ag/AgCl secondary electrode. All potentials were internally referenced to the ferrocene/ferricenium couple. Calculations. Full geometry optimizations were performed in the gas phase by using density functional theory (DFT) calculations based on the B3LYP

Inter- and intramolecular enantioselective carbolithiation reactions

• Asier Gómez-SanJuan,
• Nuria Sotomayor and
• Esther Lete

Beilstein J. Org. Chem. 2013, 9, 313–322, doi:10.3762/bjoc.9.36

• intermediates that can be converted into various types of chiral ferrocene derivatives through diastereoselective ortho-lithiation [21]. Some years ago, the concept of flash chemistry was proposed, involving fast chemical synthesis by using flow microreactors, which enabled the use of highly reactive

New enzymatically polymerized copolymers from 4-tert-butylphenol and 4-ferrocenylphenol and their modification and inclusion complexes with β-cyclodextrin

• Adam Mondrzyk,
• Beate Mondrzik,
• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2118–2123, doi:10.3762/bjoc.8.238

• combined successfully with mono-6-azido-6-deoxy-β-cyclodextrin (6) in a click-type reaction to give copolymer 7 (Scheme 1). ROESY measurements show some weak interaction of the protons of β-CD with the protons of the ferrocene (Fc) moiety and the tert-butyl-moiety (Supporting Information File 1

• ferrocene- and β-cyclodextrin-containing copolymer 7. Supporting Information File 324: ROESY of copolymer 7.

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• ; ferrocene; rhodium; Introduction Ferrocene and its derivatives are among the most useful organometallic compounds because of their chemical and thermal stabilities, structures, and redox activity [1][2]. One of the most remarkable applications of ferrocene derivatives is as chiral ligands [3][4]. A variety

• ]. Planar chiral 1,2-disubstituted ferrocene derivatives are usually synthesized by using diastereoselective ortho-lithiation of monosubstituted ferrocenes with an appropriate chiral ortho-directing substituent such as chiral amines, sulfoxides, and oxazolines [3]. However, this method suffers from low atom

• economy, and requires stoichiometric amounts of metal reagents. Functionalization of ferrocene derivatives by transition-metal-catalyzed enantioselective C–H activation is a potentially more atom-economical alternative. However, only a few catalytic C–H activation reactions of ferrocenes have been

Modulating the activity of short arginine-tryptophan containing antibacterial peptides with N-terminal metallocenoyl groups

• H. Bauke Albada,
• Alina-Iulia Chiriac,
• Michaela Wenzel,
• Maya Penkova,
• Julia E. Bandow,
• Hans-Georg Sahl and
• Nils Metzler-Nolte

Beilstein J. Org. Chem. 2012, 8, 1753–1764, doi:10.3762/bjoc.8.200

• of small synthetic arginine and tryptophan containing peptides was prepared and analyzed for their antibacterial activity. The effect of N-terminal substitution with metallocenoyl groups such as ferrocene (FcCO) and ruthenocene (RcCO) was investigated. Antibacterial activity in different media

• activity of WRWRW-peptides against Gram-positive and Gram-negative bacteria. MIC values of 2–6 µM for RcCO-W(RW)2 and 1–11 µM for (RW)3 were determined. Interestingly, W(RW)2-peptides derivatized with ferrocene were significantly less active than those derivatized with ruthenocene which have similar

• constructs [33]. Our group has previously shown that the covalent attachment of metal complexes to RW-based synAMPs yields more active derivatives with a changed activity profile for Gram-positive and Gram-negative bacteria. In this work, the attachment of the neutral ferrocenoyl group (ferrocene

Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119

• unit of 1,1',3,3'-tetrasubstituted ferrocene, two phenyl groups as scissor blades and two phenylethylene groups as handles linked through an azobenzene [117][118]. The light irradiation of λ = 350 nm (180 min) leads to a mixture of isomers trans/cis 11:89, while exposure to visible light (λ > 400 nm

• , 15 min) again enriches 46% of the trans isomer. The molecular motion was studied by circular dichroism (CD), 1H NMR and DFT calculations confirming that the change in the configuration of the N=N double bond modifies the initial position of the ferrocene resulting in an opening (cis) and closing

• enrichment of the trans isomer (63%). The study of the photoisomerization process of 13 revealed that the configurational change of the azobenzene unit causes a sequence of molecular motions of the units connected to it. The ferrocene unit rapidly responds by turning, which in turn induces an opening motion

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• glass tube with a surface area of A = 0.785 mm2, which was polished down to 0.5 µm with Buehler polishing paste prior to use. The counter electrode consisted of a platinum wire and the reference electrode was an Ag/AgCl secondary electrode. All potentials were internally referenced to the ferrocene

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

• Nicholas G. White and
• Paul D. Beer

Beilstein J. Org. Chem. 2012, 8, 246–252, doi:10.3762/bjoc.8.25

• Nicholas G. White Paul D. Beer Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom 10.3762/bjoc.8.25 Abstract A ferrocene bis(triazole) macrocycle was synthesised in good yield by the Eglinton coupling of an acyclic bis(alkyne) precursor and characterised in the solid

• that the redox-active macrocycle is capable of sensing chloride in CH3CN solution. Keywords: anion binding; C–H···anion interactions; electrochemistry; ferrocene; triazolium; Introduction The copper(I)-catalysed cycloaddition of alkynes and azides (CuAAC) [1][2] to give the 1,2,3-triazole group is

• ][7]. More recently, we [8], and others [9][10], have shown that alkylating the triazole group to give the triazolium group increases the strength of anion binding significantly by further polarising the C–H bond of the heterocycle. With one notable recent exception of an acyclic ferrocene-appended

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• . Ferrocene was added as an internal standard on completion of each experiment and tabulated potentials are given vs the saturated calomel electrode [E0(Fc/Fc+) = 460 mV vs SCE (dichloromethane)]. Cyclic voltammetry was performed with a sweep rate of 100 mVs−1. X-ray crystallography Crystals were mounted

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• phenothiazine derivatives 72 starting from primary amines, 2-bromothiophenol and substituted 1-bromo-2-iodobenzenes [40]. Ferrocene ligands, such as dppf, and Pd2dba3 as the palladium source were found to be the most suitable and efficient catalyst systems for the preparation of a series of phenotiazine

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• 165, 166), and Fc is the abbreviation of ferrocene of molecular formula C5H4FeC5H5. From the reaction of 5-(chloromercuri)-nucleosides 4 or 94 with ethenylferrocene, methoxyderivatives 164 or 167 were also formed along with nucleosides 165, 166, 168 and 169. Synthesis of pseudouridines Pseudouridine

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• spectroelectrochemical plots of P-25 and P-26 as thin films on ITO glass. Scan rate: 100 mVs−1; potential vs. ferrocene (from [50]). Synthesis of DPP monomers. Pd-catalyzed coupling reactions for preparation of DPP-containing polymers. Thiophenyl-DPP-based polymers. List of diphenylDPP-based polymers prepared upon

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• the disalts. All of the cyclic voltammograms showed reversible redox chemistry, featuring the transfer of two electrons, as indicated by calibration with ferrocene/ferrocenium (Fc/Fc+). Restricting the bridge length to two carbons made donor 14 a less effective reducing agent (Figure 3) compared to 8

Free radical homopolymerization of a vinylferrocene/cyclodextrin complex in water

• Helmut Ritter,
• Beate E. Mondrzik,
• Matthias Rehahn and
• Markus Gallei

Beilstein J. Org. Chem. 2010, 6, No. 60, doi:10.3762/bjoc.6.60

• insoluble in water. Complexation of 1 with methyl-β-cyclodextrin 2 results in clearly water-soluble structures due to incorporation of the ferrocene moiety into the cyclodextrin cavity. After free radical polymerization of the water-soluble complexed monomer, corresponding to polyvinylferrocene (PVFc), the

• scanning calorimetry (DSC), and lower critical solution temperature (LCST) measurements. Keywords: cyclodextrin; free radical polymerization; polyvinylferrocene; vinylferrocene; Introduction Since its discovery in 1951, ferrocene [1] and its derivatives and their applications have been the subject of

• a second step, the reduction of PVFc+ 6 to PVFc 4 was exothermic, hence the complexed polyvinylferrocene 3 was destabilized and the orange colored reduced form of polyvinylferrocene 4 precipitated, indicating that the individual ferrocene units along the chain no longer fit into the cavity of the

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

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• was stirred for 2 h at room temperature. A solution of ferrocene carboxaldehyde (10-fold excess based on initiator) in CH2Cl2 was added and the mixture was stirred for 1 h at room temperature. The polymer was precipitated by addition of pentane, filtered off, thoroughly washed with pentane and dried

• mmol) was dissolved in 5 mL of CH2Cl2 and treated with a solution of [Mo] (3.0 mg, 0.0042 mmol) in 1 mL of CH2Cl2. The resulting white cloudy reaction mixture was stirred for 2 h at room temperature. A solution of ferrocene carboxaldehyde (10-fold excess based on initiator) in CH2Cl2 was added and the

• dissolved in 2 mL of CH2Cl2 and this solution was added to the reaction mixture. The resulting white cloudy reaction mixture was stirred for another 90 min. The polymerization was terminated with ferrocene carboxaldehyde (10-fold excess based on initiator) and the reaction was stirred for a further hour

Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

• Andreas Speicher,
• Timo Backes,
• Kerstin Hesidens and
• Jürgen Kolz

Beilstein J. Org. Chem. 2009, 5, No. 71, doi:10.3762/bjoc.5.71

• was obligatory to prevent exclusive pinacolborane reduction. ddppf: 1,1′-bis(diphenylphosphino)ferrocene. Synthesis of the tolane precursors 27 and 28 for cyclization. Synthesis of the modified macrocycles 5–7 from the dialdehyde precursors 28–30. Synthesis of the known macrocycle 3 via McMurry

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles

• Dingqiao Yang,
• Ping Hu,
• Yuhua Long,
• Yujuan Wu,
• Heping Zeng,
• Hui Wang and
• Xiongjun Zuo

Beilstein J. Org. Chem. 2009, 5, No. 53, doi:10.3762/bjoc.5.53

• molecules with the dihydronaphthalene skeleton. Results and Discussion The ARO reaction involves many components of the chemical agents; we first attempted to optimize the ligand to iridium catalyst system (Scheme 1). In our initial experiments, we chose an achiral 1,1′-bis(diphenylphosphino)ferrocene (DPPF

Synthesis of mesogenic phthalocyanine-C₆₀ donor–acceptor dyads designed for molecular heterojunction photovoltaic devices

• Yves Henri Geerts,
• Olivier Debever,
• Claire Amato and
• Sergey Sergeyev

Beilstein J. Org. Chem. 2009, 5, No. 49, doi:10.3762/bjoc.5.49

• as a working electrode. A spiral platinum wire was employed as counter electrode and an Ag/AgCl/KCl(sat) used as reference electrode was connected to the cell solution via a salt bridge containing a saturated aqueous KCl solution. The Ag/AgCl electrode was checked against the ferrocene/ferrocinium