Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• SET mechanism to generate a radical cation B, followed by fragmentation to afford 12 (Scheme 3b). Either of these processes provided the imine moiety, along with o-iodosobenzoic acid (IBA, Scheme 3). In general, IBX-mediated oxidative dehydrogenation is conducted at high temperatures (>50 °C

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

• stoichiometric amount of Cu(OAc)2 and H2O in acetonitrile at 130 °C, and the resulting acetate gave phenols in moderate yields through a simple hydrolysis (Scheme 25). A mechanistic investigation revealed that the reaction proceeded via a radical-cation pathway. Notably, their protocol could be also applied in

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

• Markus Menke,
• Pardha Saradhi Peram,
• Iris Starnberger,
• Walter Hödl,
• Gregory F.M. Jongsma,
• David C. Blackburn,
• Mark-Oliver Rödel,
• Miguel Vences and
• Stefan Schulz

Beilstein J. Org. Chem. 2016, 12, 2731–2738, doi:10.3762/bjoc.12.269

• , leading to the radical cation 18 along pathway a. An additional bond cleavage of a C–O single bond releases a neutral molecule, e.g., methylcyclohexane, giving rise to ion m/z 126 (20). High-resolution mass spectral data support the hypothesis because the ions m/z 126 as well as m/z 182 (25) formed from 2

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• (SET), reducing the iridium complex to Ir(II) III and oxidizing the the nitrogen of THIQ IV to its radical cation V, which then undergoes a hydride abstraction to form the iminium salt form VI, of the THIQ. The pre-formed chiral PhCu–PyBox complex [38], coordinates to the iminium cation VI, followed by

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

• Patrick Rabe and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

• fragment ion m/z = 43 from C3 and C15 (Scheme 4E). As shown by HRMS analysis, this fragment ion contains oxygen (measured: 43.0183, calculated for [C2H3O]+: 43.0179). The radical cation 3a+· can undergo two sequential or consecutive α-fragmentations to K3+·. A subsequent hydrogen rearrangement to L3+· and

• ). Electron impact ionisation at the oxygen lone pairs of 4 results in the radical cation 4a+· that can undergo one of two possible α-cleavages with loss of C12 or C13 to yield A4+. The alternative ionisation of 4 with loss of an electron from the olefinic double bond leads to 4b+· that may react by hydrogen

• radical cation K4+·. Another α-cleavage of the hydroxyisopropyl group results in L4+. Finally, the PMA59 demonstrates formation of this fragment ion from the hydroxyisopropyl group which is possible by a single α-cleavage from 4a+· to M4+ (Scheme 5F). Conclusion Isotopic labelling experiments continue to

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• a charge shift (CS) to generate an intermediate excited species, that is a combination of charge neutral radical, i.e., a quinolizinyl radical, and the radical cation of the aromatic substituent (Scheme 3). The proposed photoinduced charge shift in derivatives 6b–e is supported by observations that

• relaxation, the counter anion migrates to the radical cation unit at the aryl substituent. At the same time, this mechanism implies that directly after the "back CS" the bromide anion is still located in the vicinity of the aryl substituent and therefore no longer compensated by a nearby cationic charge

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• most energetically favorable conformation of inclusion complexes. Finally, the effect of encapsulation on the antioxidant properties of 1 and 2 was evaluated using the ABTS radical cation assay. Results and Discussion UV–visible competitive studies Stoichiometries and Kf values of inclusion complexes

• ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS•+) scavenging method was used to determine the radical scavenging potency of free and encapsulated 1 and 2. This method relies on the capacity of an antioxidant to scavenge and reduce ABTS•+ into its colorless reduced

Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

• Xiang Sun,
• Guoqiao Lai,
• Zhifang Li,
• Yuwen Ma,
• Xiao Yuan,
• Yongjia Shen and
• Chengyun Wang

Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255

• to explore the formation of the charge-transfer complexes. TTF derivates are representative electron donors, while TCNQ is a typical electron acceptor. When one equivalent of TCNQ was added to the solution of T1 in ethyl acetate, TCNQ radical anion species (TCNQ•−) and TTF radical cation species (TTF

• +0.643 V (T2) (vs Ag/AgCl) was in the anodic window. This indicated the successive reversible oxidation of neutral TTF (TTF0) to the radical cation (TTF•+). The second oxidation at = +0.958 V (T1) and +0.973 V (T2) (vs Ag/AgCl) corresponded to the reversible oxidation of the radical cation (TTF•+) to

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• solution. The reaction of dioxygen (3O2) having a triplet ground state with tetrahydropyridine 1 having a singlet ground state is spin forbidden. On the other hand, the electron transfer from the organic compound to 3O2 resulting in the formation of a radical cation of the organic donor and the radical

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• cavity of cucurbit[8]uril (CB[8]) are highlighted. Keywords: donor–acceptor interaction; foldamer; hydrogen bond; radical cation dimerization; supramolecular organic framework; Review Childhood and growing up I was born on July 23rd, 1966 in the small, remote village of Fang-Liu (a combination of two

• favorite. Many years later at Fudan, I initiated a project to study the potential of its radical cation stacking in controlling the folded conformation of linear molecules and two- and three-dimensional supramolecular polymers and frameworks. My life in the small town of Odense was also memorable. Its calm

• successive intramolecular C–H····F or C–H····Cl hydrogen bonds [70]. Conjugated radical cation dimerization-driven pleated foldamers. The stacking of the radical cations of viologen or TTF were observed in 1964 and 1979 [71][72]. This stacking is typically weak. Several approaches have been developed to

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• polymer thin film revealed the splitting of the first oxidation wave during the cathodic run, which the authors attributed to a stepwise reduction from the aggregated radical cation to an intermediate mixed valence state, then further reduction to the neutral species. To decrease the difference in the

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• self-aggregated in chloroform–dioxane to form a gel. TEM images of the xerogel exhibited helical molecular tapes nanometer wide and micrometer long. A cyclic voltammetry (CV) study on 2b showed the redox properties expected for Pc and TTF, and doping of 2b in CH2Cl2 with I2 produced a radical cation

• of 40, the changes show several isosbestic points, indicating that each TTF unit is oxidized from the neutral to the radical cation (TTF•+) in a stepwise manner (Figure 15b). On the other hand, for 38 and 42, there are no isosbestic points (Figure 15a,c). For 38, a new broad peak around 1850 nm

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• this review we describe how photoactivated SCPCs can either (i) interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii) interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of

• . Alternatively, *Ru(bpy)32+ acts as an oxidant by accepting an electron from a suitable donor molecule D thus creating the radical cation D+•. Successful protocols have been developed for a variety of preparations including: enantioselective α-alkylations of aldehydes with radicals derived from α-bromocarbonyl

• where the electron can reduce an electron acceptor with a suitable redox potential to a radical anion (A–•) and/or the hole can oxidize an electron donor to the radical cation (D+•, Figure 1). Recombination, whereby the electron drops back down to the VB, occurs in competition with this in the bulk of

Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

• Sara J. Krivickas,
• Chiho Hashimoto,
• Junya Yoshida,
• Akira Ueda,
• Kazuyuki Takahashi,
• John D. Wallis and
• Hatsumi Mori

Beilstein J. Org. Chem. 2015, 11, 1561–1569, doi:10.3762/bjoc.11.172

• due to their ability to form radical cation salts with interesting conductive and magnetic properties (Figure 1). The influence of chirality in the TTF molecules on the crystal structure and physical properties has been shown by Avarvari’s (R)-, (S)- and racemic (±)-(ethylenedithio(tetrathiafulvalene

• molecules, and anions in the subsequent radical cation salts [20][21][22]. This may lead to improved order in the crystalline state, which in turn may help the observation of physical properties of the salts. Previously, the synthesis of racemic-2 [21][22], the preliminary synthesis of enantiopure (R,R

• )- and (S,S)-2, and the preparation, and crystal structure of the radical cation salt α’-[(S,S)-2]2ClO4 [22] have been reported. In this article, we report the syntheses of novel racemic-1 and enantiopure (R,R)- and (S,S)-2 possessing one or two hydroxymethyl groups, and the preparations, crystal

Tetrathiafulvalene chemistry

• Peter J. Skabara and
• Marc Sallé

Beilstein J. Org. Chem. 2015, 11, 1528–1529, doi:10.3762/bjoc.11.167

• nineteen seventies [1][2][3] and since then has proved to be exceptionally popular in various fields of chemistry. This success results from the conjunction of intrinsic structural and electronic properties: i) structurally, this sulfur-rich bicyclic compound is essentially planar (at least in the radical

• cation state) and therefore presents, as with most of its substituted derivatives, a good propensity to stack in the solid state. This parameter is favorable for efficient charge delocalization in the solid-state and it is this feature that gave birth to the first conducting and superconducting organic

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• prepared electroactive rhenium complex the TTF is neutral and the rhenium cation is hexacoordinated. The electrochemical behavior of the three compounds indicates that they are promising for the construction of crystalline radical cation salts. Keywords: azine ligand; fluoride sensing; rhenium

• ; tetrathiafulvalene; X-ray; Introduction Tetrathiafulvalene (TTF) is known to have excellent electron-donating properties resulting in stable radical cation (TTF•+) and dication (TTF2+) species from two sequential and reversible oxidation processes. The huge interest in the synthesis of TTF and its very numerous

• electrochemical behavior observed for L2 and its corresponding rhenium complex 3 indicate that this compounds are valuable candidates for the electrochemical formation of air-stable radical cation crystalline salts [16]. Conclusion Two multifunctional ligands which associate an electron-donating TTF unit with an

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• been utilized in the formation of charge-transfer (CT) complexes for more than 40 years [21][22][23]. TTF (1) (Figure 1) is not aromatic according to the Hückel definition as its 14 π-electrons lack cyclic conjugation. Upon oxidation to the radical cation (2) and dication (3) states, a gain in

• materials with applications in supramolecular chemistry, molecular electronics and as sensors. The sequential, reversible oxidation of TTF (1) to its stable radical cation (2) and dication (3) states. Structures and possible substitution positions of MPTTFs (4) and BPTTFs (5). Large-scale synthesis of 6

Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones

• Flavia Pop and
• Narcis Avarvari

Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124

• conformation. Cyclic voltammetry measurements indicate fully reversible oxidation in radical cation and dication species. Keywords: chirality; crystal structures; molecular materials; sulfones; tetrathiafulvalenes; Introduction Chiral tetrathiafulvalene (TTF) derivatives have been addressed for the first

• -oxaziridines as oxidizing agent [27][28]. However, the inner BEDT-TTF sulfoxide was shown to be of only limited interest as precursor for molecular conductors, since it does not reversibly oxidize into a radical cation. This behavior is due to the moderate kinetic stability of the latter, which releases oxygen

• to transform into BEDT-TTF. Moreover, since the inner sulfur atoms present large orbital coefficients in the HOMO, the introduction of the electron-withdrawing oxygen atom induces a massive increase of the oxidation potential from the neutral to the radical cation states. We have then hypothesized

Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F₄TCNQ

• Raúl García,
• M. Ángeles Herranz,
• Edmund Leary,
• M. Teresa González,
• Gabino Rubio Bollinger,
• Marius Bürkle,
• Linda A. Zotti,
• Yoshihiro Asai,
• Fabian Pauly,
• Juan Carlos Cuevas,
• Nicolás Agraït and
• Nazario Martín

Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120

• -dithiol-2-ylidene)-9,10-dihydroanthracene) which, in contrast to pristine TTF that exhibits two oxidation peaks to form the radical cation and dication species, shows only one oxidation peak involving a two electron process to form the dication state. Furthermore, the geometrical properties of exTTF are

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• existence of intermolecular interactions and the formation of mixed-valence and radical cation dimer states. These results clearly demonstrated the presence of an intermolecular mixed-valence phenomenon. According to these first results, the following model could be proposed in agreement with the successive

• ]catenane [53], cucubit[8]uril [54] or self-assembled cages [55] which facilitate the formation of TTF dimers. Studying the glycoluril-based molecular clip 15 presenting also TTF sidewalls [56][57], Chiu et al. have observed the mixed-valence and radical cation dimer states at high concentration (10−3 M

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

• Masashi Hasegawa,
• Junta Endo,
• Seiya Iwata,
• Toshiaki Shimasaki and
• Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

• )tetrathiafulvalenylbenzene radical cation 10•+, which was reported previously [7] (Table 2). In the spectrum of 32+, the absorption maximum at 810 nm is assigned to an electronic transition to the SOMO in the TTF•+ moieties. The value was slightly red-shifted compared with that of 10•+ (775 nm). This small bathochromic

Carboxylated dithiafulvenes and tetrathiafulvalene vinylogues: synthesis, electronic properties, and complexation with zinc ions

• Yunfei Wang and
• Yuming Zhao

Beilstein J. Org. Chem. 2015, 11, 957–965, doi:10.3762/bjoc.11.107

• observed at +0.82 V in the first cycle of scan, which is due to the single-electron oxidation of the dithiole moiety into the dithiolium radical cation [15][16]. In the reverse scan, a cathodic peak emerged at +0.54 V which is assigned to the bielectronic reduction of the TTFV product electrochemically

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• structure, as in the radiaannulene 2a, communication between the two TTFs is observed in the cyclic voltammetry experiment, and the first two-electron event showed the waves diverging from each other (two stepwise oxidations) [10]. In addition, the intermediate radical cation showed an IVCT absorption at

• -ethynylpyridine linkers. When two TTFs are closer together via an ethyne spacer (4), the two waves are rather broad. In fact, a shoulder can be seen for each wave, which indicates weak interactions between the two units, not only for generating two TTF radical cation units, but also for the final generation of

• −1 used for these studies, the reversibility remains unchanged confirming the high stability of the formed radical cation and dication states within each TTF redox site (in further text defined as “polaron” and “bipolaron” states, respectively; see Scheme 4). The small peak separation, ΔE, between

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• aromatic MPTTF conjugates were determined using cyclic voltammetry (CV) in CH2Cl2/Bu4NClO4 solution and are summarized in Table 1. The CVs of all compounds displayed two reversible oxidation waves on the cathodic scan (Figure 4) characteristic to TTFs [1], the first one leading to the radical cation and

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

• Longfei Ma,
• Jibin Sun,
• Xiaofeng Lu,
• Shangxi Zhang,
• Hui Qi,
• Lei Liu,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 850–859, doi:10.3762/bjoc.11.95

• –, and coexistence of planar [Cu(II)Br4]2– and tetrahedral [Cu(II)Br3]– ions. On the other hand, the TTFs show either radical cation or dication states that depend on their redox potentials. The central TTF framework on most of TTFs is nearly planar despite the charge on them, whereas the two dithiole

• -based conducting materials are mainly produced as radical cation salts by electrochemical oxidation and CT complexes by chemical oxidation with electron acceptors [5][6]. Most Ar-S-TTFs possess redox potentials higher than that of bis(ethylenedithio)-TTF (BEDT-TTF) [33][34][35][36][37][38][39

• potentials of 1–7 are summarized in Table 1. As reported in the following section, TTFs 1–5 have the E1/22 < 0.90 V and form the dicationic salts by reaction with CuBr2. On the contrary, the E1/22 values of 6 and 7 are higher than 0.90 V, and these two donor molecules form the radical cation salts by