The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• conditions [32][33]. Although the introduction of an electroauxiliary requires an additional synthetic step to prepare, the resulting carbon–tin, carbon–silicon or carbon–sulfur bond has a less positive oxidation potential than an unfunctionalised carbamate. Therefore, exquisite control can be exerted on the

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• groups are therefore not compatible with direct oxidation [48]. A milder and more selective approach is represented by the installation of an electroauxiliary (EA), a functional group which lowers the oxidation potential of the compound, in α-position to the oxygen/nitrogen [30][49]. In this context, the

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• +0.73 V. In both cases, the first oxidation wave is assigned to the formation of the radical cation on one of the bi/terthiophene segments of the molecule. The lower oxidation potential for 10 compared to 9 is consistent with the tendency to decrease the oxidation potential when the oligothiophene chain

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• focused on the fixation of CO2 using sacrificial anodes [38][39][40] (Scheme 6a). The higher oxidation potential of sacrificial anodes compared to that of the other reaction species makes this setup readily compatible with a simple undivided electrolysis cell, without a membrane separating the catholyte

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

• Sarah Bay,
• Gamall Makhloufi,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 1006–1016, doi:10.3762/bjoc.10.100

• have become attractive electrophores due to their reversible and tunable oxidation potential. Interestingly quenching of the phenothiazine inherent fluorescence offers a facile evidence for the occurrence of intramolecular PET in phenothiazine-containing Do–Acc dyads [41][42]. As suitable acceptor

• ] Where is the difference of the first oxidation potential of the donor and first reduction potential of the acceptor, respectively, E00 expresses the energy of the photonic excitation, RDo–Acc delineates the distance between the centers of the donor and acceptor moieties, εs and εref are the dielectric

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• ]. The last important step is the dye regeneration. In order for the cycle and for the catalytic behavior to occur, the corresponding Gibbs free energy change should be negative. If one assumes that the reduction potential of PS•+ is given by the oxidation potential of PS, then . Thus, in order to

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• ]. Such long lifetimes for triplet states are important in photoredox catalysis to ensure an efficient quenching by the oxidation agents. Ir(piq)2(tmd) is characterized by an oxidation potential of 0.67 V vs SCE (Figure 7A); its triplet-state energy level (ET ~ 2.07 eV) was determined from absorption

• and C are the oxidation potential of Ir(piq)2(tmd), the reduction potential of Ph2I+, the excited triplet state energy of Ir(piq)2(tmd), and the electrostatic interaction energy for the initially formed ion pair, generally considered as negligible in polar solvents) [69]. This favorable 3PIC/Ph2I

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

• oxidation potential E1/20/+1. This gap was estimated by the cross-section of the absorption and emission spectra. For the missing oxidation potentials of 2f, 2g, 2m, and 2l the HOMO and LUMO energies were determined by DFT calculations [48]. For validation of the experimental and computational data the

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• carbophilicity, low oxophilicity and high oxidation potential between gold(I) and gold(III) have shown a unique potential to unveil novel types of chemoselective and stereoselective cycloadditions involving alkynes, allenes or alkenes [24][25][26]. A lot of interest has been directed to the development of these

Anodic coupling of carboxylic acids to electron-rich double bonds: A surprising non-Kolbe pathway to lactones

• Robert J. Perkins,
• Hai-Chao Xu,
• John M. Campbell and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2013, 9, 1630–1636, doi:10.3762/bjoc.9.186

• afforded the five-membered ring product using either lithium methoxide or 2,6-lutidine as a base. Clearly, decarboxylation of the carboxylate anion was not a problem. In fact, cyclic voltammetry data suggest that the reaction originated from an oxidation of the ketene dithioacetal. The oxidation potential

• (Ep/2) for 14a was measured to be +0.68 V versus Ag/AgCl. For comparison, the oxidation potential measured for 10-undecenoic acid was +1.91 V versus Ag/AgCl in DMF solvent and +1.85 V versus Ag/AgCl in acetonitrile. When 0.5 equivalents of benzyltrimethylammonium hydroxide was added to the cyclic

• voltammetry solutions in order to generate the carboxylate and mimic the preparative oxidation conditions used for the reaction originating from 14a, the oxidation potential of the 10-undecenoic acid fell to 1.36–1.40 V versus Ag/AgCl for the DMF solution and 1.38 V versus Ag/AgCl for the acetonitrile

Structures of the reaction products of the AZADO radical with TCNQF₄ or thiourea

• Hideto Suzuki,
• Yuta Kawahara,
• Hiroki Akutsu,
• Jun-ichi Yamada and
• Shin’ichi Nakatsuji

Beilstein J. Org. Chem. 2013, 9, 1487–1491, doi:10.3762/bjoc.9.169

• -configuration. The cyclic voltammetry (CV) data of TEMPO (1), AZADO (2), TCNQF4 (3) and the adduct 5 are summarized in Table 1. The lower first oxidation potential (E1OX) of AZADO than that of TEMPO suggests that the reaction between AZADO and TCNQF4 can take place slightly more easily than that between TEMPO

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

• potential of the donor, the reduction potential of the acceptor, the excited state energy and the coulombic term for the initially formed ion pair, respectively. C is neglected as usually done in polar solvents. Fluorescence experiments The fluorescence properties of the different Co_Pys were studied by

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

• a more positive value (ΔE ≈ 40 mV) compared to the terthiophene dendron [42]. The oxidation potential of the second-generation ligand 9 was also positively shifted by 30–60 mV compared to the corresponding dendron. This positive potential shift is the consequence of a stabilization of the tpy ligand

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

• Maurizio Fagnoni,
• Stefano Protti,
• Davide Ravelli and
• Angelo Albini

Beilstein J. Org. Chem. 2013, 9, 800–808, doi:10.3762/bjoc.9.91

• from 2,6,9,10-tetracyanoanthracene with amines [38]). As for the donors, these were chosen on the basis of their oxidation potential (see Table 1 and Figure 1), to allow for an overall exergonic electron transfer from the donor to the excited acceptor in all of the cases considered below [39]. The

• oxidation potential of the ground-state donors examined in this work. aValue measured in the present work (see Experimental). UV-monitoring of: (a) a 2 × 10−4 M solution of TCB in the presence of Bu4Sn (10−2 M) and (b) a 1.5 × 10−4 M solution of TCB in the presence of OXA (5 × 10−2 M) in freeze–pump–thaw

Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

• Carolin Regenbrecht and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2012, 8, 1721–1724, doi:10.3762/bjoc.8.196

• trimerization protocol [14][15][16]. Usually, yields are in a moderate range (≤35%) [15] when the electrolysis is performed on platinum or graphite anodes in anhydrous and non-nucleophilic electrolytes [14]. Poor yields are caused by the low oxidation potential of the products and the preference for over

The effect of the formyl group position upon asymmetric isomeric diarylethenes bearing a naphthalene moiety

• Renjie Wang,
• Shouzhi Pu,
• Gang Liu and
• Shiqiang Cui

Beilstein J. Org. Chem. 2012, 8, 1018–1026, doi:10.3762/bjoc.8.114

• molecular orbital (LUMO) energy level, the band gap Eg (Eg = LUMO–HOMO) of 1o and 1c can be determined to be +2.50 and +2.67 eV. Similarly, the oxidation potential of 2o and 3o is initiated at +1.76 and +1.83 V, and that of 2c and 3c is initiated at +1.74 and +1.79 V. The results indicate that the oxidation

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

• the 2-vinylthiophene subunit at 1.15 V and 1.13 V vs Fc/Fc+, respectively. For co-oligomer 11, the oxidation potential was significantly higher (1.23 V) and indicates formation of a radical cation localized on the thiophene subunits. In the negative regime, no reduction wave for the 1,2,3-triazole

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

• caused a cathodic shift of the oxidation potential of 25 mV and a loss of reversibility, which may be indicative of an EC mechanism [14] (Figure 4). Further addition of TBA·Cl led to increasing cathodic perturbations of the Epa oxidation wave of up to 40 mV after five equiv. As noted with other ferrocene

Sexithiophenes as efficient luminescence quenchers of quantum dots

• Christopher R. Mason,
• Yang Li,
• Paul O’Brien,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2011, 7, 1722–1731, doi:10.3762/bjoc.7.202

• . The corresponding reduction process is also shifted from +0.56 V to +0.41 V. The second oxidation potential for 1b experiences a shift to lower values (1.04 V compared to 0.89 V), but the reversibility is diminished somewhat; ΔE2a–c (mV) 2b, 170 mV; 1b, 270 mV. The decrease in oxidation potentials of

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

• give rise to a lower oxidation potential of the polymer. Relevant polymers P-16 - P-20 (Table 3) were synthesized using Pd-catalyzed aryl amination reactions as reported by Hartwig [38][39], Buchwald [40][41][42], and Kanbara [43][44][45][46][47]. As shown in Scheme 2, DPP monomers such as M-1 were

• , respectively. The absorption and emission colours are shown in Figure 4. Stille coupling of M-1 and 2-(tributylstannyl)-3,4-ethylenedioxythiophene gave the corresponding bis(thienyl)-substituted monomer [49]. Due to presence of the EDOT units, the monomer exhibited a rather low oxidation potential and could be

• reversible electrochromic properties whereas the polymer with EDOT-phenyl groups in the 2- and 5- positions (structure II in Table 4) is non-conjugated, possesses a high oxidation potential and is not electrochromic (Figure 5). Our activities have stimulated several other groups to synthesize diphenylDPP

Synthetic incorporation of Nile Blue into DNA using 2′-deoxyriboside substitutes: Representative comparison of (R)- and (S)-aminopropanediol as an acyclic linker

• Daniel Lachmann,
• Sina Berndl,
• Otto S. Wolfbeis and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2010, 6, No. 13, doi:10.3762/bjoc.6.13

• Ered −0.3 V (vs. NHE), the excited state potential is estimated to be E*red = 2.2 eV [17]. Hence, a photooxidation of guanine is highly favorable because the oxidation potential of guanine is only ~1.3–1.4 V [44]. Hence sequence-dependent fluorescence quenching of the Nile Blue dye in DNA was expected

Prediction of reduction potentials from calculated electron affinities for metal-salen compounds

• Sarah B. Bateni,
• Kellie R. England,
• Anthony T. Galatti,
• Handeep Kaur,
• Victor A. Mendiola,
• Alexander R. Mitchell,
• Michael H. Vu,
• Benjamin F. Gherman and
• James A. Miranda

Beilstein J. Org. Chem. 2009, 5, No. 82, doi:10.3762/bjoc.5.82

• whether a potential substituted triphenylamine was likely to have a high enough oxidation potential to be useful as an electrocatalyst for a difficultly oxidized organic substrate before embarking upon a proposed synthesis of the substituted triphenylamine. By using Fry’s method of calculating EAs to

Synthesis and redox behavior of new ferrocene- π-extended- dithiafulvalenes: An approach for anticipated organic conductors

• Abdelwareth A. O. Sarhan,
• Omar F. Mohammed and
• Taeko Izumi

Beilstein J. Org. Chem. 2009, 5, No. 6, doi:10.3762/bjoc.5.6

• cyclic voltammetry at ambient temperature on a Pt working electrode, using TBAP as the supporting electrolyte. The CV exhibited good donor properties, showing a one-electron quasireversible oxidation potential. The oxidation potential values, and to a larger extent the reduction potential values, are

• strongly influenced by the scan rate. Increasing the scan rate from 20 to 600 mV s−1 leads to an increase of the oxidation potential values. The Fc-DTF derivatives 9 and 12 were prepared as side products during the synthesis of the targeted compounds as 1,1′-bis(1,3-DTF)Fc’s 8, 10 and 11 in variable yields

Generation of pyridyl coordinated organosilicon cation pool by oxidative Si-Si bond dissociation

• Toshiki Nokami,
• Ryoji Soma,
• Yoshimasa Yamamoto,
• Toshiyuki Kamei,
• Kenichiro Itami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2007, 3, No. 7, doi:10.1186/1860-5397-3-7

• was found that the introduction of a coordinating group such as a pyridyl group decreased the oxidation potential of tetraalkylstannanes, although there is no indication of the coordination in the neutral molecule. Dynamic intramolecular coordination to tin seems to facilitate electron transfer [22

• pyridyl group as a donor ligand. First, we prepared disilanes having pyridyl groups in appropriate positions and measured their oxidation potentials [24][25]. The oxidation potential of 2-pyridylethyl substituted disilane 1b was slightly less positive than hexamethyldisilane 1a. On the other hand, the

• oxidation potential of 2-pyridylphenyl substituted disilane 1d was much less positive than the corresponding disilane 1c having phenyl groups (Figure 1). 29Si NMR chemical shifts of 1b and 1d were similar to those of 1a and 1c, indicating that no coordination of the pyridyl groups on silicon existed in the

Effect of transannular interaction on the redox- potentials in a series of bicyclic quinones

• Grigoriy Sereda,
• Jesse Van Heukelom,
• Miles Koppang,
• Sudha Ramreddy and
• Nicole Collins

Beilstein J. Org. Chem. 2006, 2, No. 26, doi:10.1186/1860-5397-2-26

• correlation illustrates that similarly to the first redox-potentials, prediction of second redox-potentials should be performed with consideration of the conformation with the highest oxidation potential, which is conformation B for quinones 2 and 3. The correlation on Figure 5 and Figure 6 demonstrate that

• formal redox-potential Eo'1, second reduction potential Epr2, second oxidation potential Epox2 and second redox-potential Eo'2) for compounds 1–5 are presented in Table 1. The computed parameters for compounds 1–5 and for their reduced species 1·−–5·− are presented in Table 2. Bicyclic quinones explored