Synthesis and properties of tetrathiafulvalenes bearing 6-aryl-1,4-dithiafulvenes

• Aya Yoshimura,
• Hitoshi Kimura,
• Kohei Kagawa,
• Mayuka Yoshioka,
• Toshiki Itou,
• Dhananjayan Vasu,
• Takashi Shirahata,
• Hideki Yorimitsu and
• Yohji Misaki

Beilstein J. Org. Chem. 2020, 16, 974–981, doi:10.3762/bjoc.16.86

• ion complexes with DDQ or iodine were reported [17][18][19][20][21][22][23][24]. Peripherally thiophene-functionalized TTFs, as potential precursors to conducting polymers, and organic metals were also prepared and characterized [25][26][27][28][29]. To design more tempting molecules, the attachment

Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

• Yongsu Li,
• Bendu Pan,
• Xuefeng He,
• Wang Xia,
• Yaqi Zhang,
• Hao Liang,
• Chitreddy V. Subba Reddy,
• Rihui Cao and
• Liqin Qiu

Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85

• from chemists because of their widespread appearance in biologically active compounds [1][2][3][4] such as vancomycin [5] and korupensamine A [6] and as useful chiral ligands in asymmetric catalysis. Different strategies with various metals and phosphine ligands had been successfully employed for the

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• obtained by photooxidation of benzaldehydes using Pt porphyrin (Pt-TMP) [49] and Pd porphyrin (2Pd) [50] (Scheme 23). Overall, the fine-tuning of the electrochemical potential of metals and porphyrins enables the oxidation of alcohols to aldehydes or aldehydes to carboxylic acids in a very controlled and

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• -abundant metals, such as copper, with radical ligands is originally known from biological systems such as metalloenzymes [1]. Among the myriad of existing enzymes, galactose oxidase (GAO) is a copper-based enzyme performing the two-electron oxidation of galactose through a mechanism involving the metal and

• phenols, ketones and 1,3-dienes (Scheme 6) [27]. C–C bond formation Complexes of radical and redox-active ligands with transition metals are known to be able to promote radical reactions through single-electron transfer (SET) processes [28]. Expanding on the research area pioneered by Wieghardt and

• scaffolds such as gem-disubstituted (21k) and trisubstituted (21i and 21n,o) aziridines (Scheme 11). Furthermore, the reaction conditions are compatible with aldehyde, ester or ketone functions. Metalloenzymes routinely rely on 3d metals and amino acid-derived coordination spheres to perform complex (multi

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• , having multiple advantages since ligand manipulation can lead to optimized photoredox properties. Unfortunately, the use of metals can pose some critical disadvantages in an organic process. Especially since the natural abundance of various noble metals that are used as photocatalysts is limited and

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• organic chemistry. Despite the impressive advances reported since the renewal of the field in 2008 [2][3][4], several issues still have to be addressed. Indeed, most of the developed reactions relied on the use of organometallic complexes of expensive noble metals, such as iridium and ruthenium [5]. Even

• though their efficiency is outstanding, their use for industrial purposes might be hampered. Indeed, the limited availability of these metals and their prices often prohibit the development of economically efficient chemical processes [6]. In addition, the depletion of natural resources raises questions

• about the future availability of these metals at a reasonable cost. With regards to organic dyes, impressive developments have been achieved, but these catalysts might suffer from a low photochemical stability, and thus hampering their use and recyclability [7]. Therefore, alternative solutions have to

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• functionalizations. Herein, we will broadly discuss the different catalytic systems that facilitate ortho and para C–H functionalization by utilization of effective and feasible photoredox catalysts (with the aid of transition metals), hydrogen atom transfer, and aerobic oxidation. Over the last two decades, direct

• electron transfer and modification of the oxidation state of the transition metal complexes. Such systems can be combined with different metals, for example, Ni, Co, Cu, Ru, Ir, etc. However, unexpectedly, copper is less toxic and can be utilized to catalyze reactions without the requirement of a ligand

• a more sustainable procedure [88] in comparison to previously reported methods [89][90][91][92]. These semiconductor photocatalysts were better because they were: (i) cheap, (ii) easily separable from the reaction mixture, (iii) compatible with other transition metals, and (iv) provided steady

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• (Michael acceptors) is one of the most relevant and versatile methods to achieve this goal [1][2][3][4]. Among the plethora of metals studied, copper-based catalytic systems proved to be highly efficient for the conjugate addition of various organometallic reagents, such as diorganozinc, triorganoaluminium

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• alkenylation of indole with n-butylacrylate in the presence of thioether ligands [32]. In the context of C–H activation reactions, the catalyst of choice has mostly been Pd [33][34]. However, as part of the search for newer and more cost-efficient catalysts, other transition metals, such as Ru, have also been

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• substituent in the 3-position [29]. Most syntheses generating 1H-pyridines make use of ethyl cyanoactate as a starting material. It can react with itself and forms a dimer by selfcondensation, catalyzed by transition metals [30][31]. Intrigued by the unusual pseudo-four-component AMAC synthesis we

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• effectively tune their physical characteristics and also reduce production costs since the routine synthesis of heteroacene structures involves cross-coupling reactions catalyzed by expensive transition metals [15]. Thus, in this paper, we would like to present an efficient metal-free synthesis of the aryl

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• ], drug uncaging [11] to photodynamic therapy [12] and optogenetics [13][14]. Inorganic lanthanide based-UCNPs are classically formulated as a mixed fluoride NaREF4. Here, RE stands for a cocktail of trivalent rare-earth metal ions containing mostly photophysically inert metals (Y, Gd) and a few percent

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• ]. Additionally, some complexes of mostly soft transition metals with ferrocenophane ligands could be identified. Herein, a main focus lies on complexes with ferrocenic thiacrown ethers as well as selenacrown ethers coordinating a transition metal occasionally inside the cavity of the ferrocenophane [78][79][80

Indium-mediated C-allylation of melibiose

• Christian Denner,
• Manuel Gintner,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2019, 15, 2458–2464, doi:10.3762/bjoc.15.238

• concerning their effects on the conversion rate as well as the diastereoselectivity (Table 1). Concerning the metal species, it is known that indium provides several advantages compared to other allylation-mediating metals such as tin, as it allows the reaction to proceed under very mild conditions without

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• (Figure 12). Studies of the TPA properties demonstrated that some of these dendrimers outperform the TPA cross-section response of quantum dots, while having a much lower intrinsic toxicity, as being composed or organic matter instead of heavy metals. The grafting of water-solubilizing functions on the

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• Asymmetry, as well as by Hitachi Metals Materials Science Foundation and Research Foundation for the Electrotechnology of Chubu. AS thanks the Ministry of Science and Higher Education of the Russian Federation (State assignment no. 4.1774.2017/4.6).

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• . Keywords: catalysis; C-RF bond; fluorination; fluoroalkylation; transition metals; Introduction Compared with other halogens (Cl, Br, I), fluorine (F) has completely different physical and chemical properties, such as a unique electronic structure, strongest electronegativity, and small atomic radius

• regard, the use of various transition metals to catalyze the synthesis of organic fluorides has become a mature field, and the application of these methodologies has allowed decreasing the need of pre-functionalized substrates, less consumption of reaction time and costs, and enabled to produce

• enantioenriched target compounds [15][16][17][18][19][20]. Furthermore, transition metals have the unique advantage of possessing multiple mechanistic features, which translates into the ability to apply new substrate classes and provide hitherto novel and inaccessible structures. Therefore, transition-metal

Friedel–Crafts approach to the one-pot synthesis of methoxy-substituted thioxanthylium salts

• Kenta Tanaka,
• Yuta Tanaka,
• Mami Kishimoto,
• Yujiro Hoshino and
• Kiyoshi Honda

Beilstein J. Org. Chem. 2019, 15, 2105–2112, doi:10.3762/bjoc.15.208

• presence of a Lewis acid such as SnCl4 and AlCl3 [12][13][14]. While these reactions were proven to be useful, they require the use of stoichiometric amounts of metals and/or toxic metal reagents. Moreover, there are only a few methods for the synthesis of thioxanthylium salts despite their useful active

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• photoredox catalytic behavior, transition metal complexes have disadvantages, including high costs due to limited availability, toxicity [22][23] and polluting properties [24]. This thwarts the principally “green” concept of photoredox catalysis. In order to avoid transition metals and enhance the

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• Ar(aryl)–Se bonds [9][10][11][12][13]. Various metals, such as Pd, Ni, Fe, and Cu have been used to catalyze the reactions of a Se source with aryl donors. Among these, Cu-catalyzed tandem cyclization via a one-step Ullmann-type Se-arylation and Csp2–H selenation are efficient methods for

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• ] (see Figure 1), although two unusual methods have also been reported [16][17]. We have been looking at alternative methods for the meta-functionalization of calix[4]arenes, with the idea of C–H activation via transition metals appearing an attractive option. Lhoták and co-workers have already attempted

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• , which promotes reactions through grinding or milling with no, or minimal, use of solvents, has been used in conjunction with halide metathesis to form organometallic compounds of the transition metals [3][4][5][6][7] and both s- [8][9] and p-block [10][11] main group elements. The extent to which the

• reduced further by choosing M to be potassium rather than lithium; as an added benefit, the resulting potassium halides are less likely to contaminate the desired product. Without a solvent present and if M and M' are both univalent metals with similar electronegativity, complete exchange becomes

• difficult, and the extent of even partial exchange is hard to predict. For the alkali metals, all electronegativity scales indicate that caesium is the most electropositive, but they also indicate that there is comparatively little variation in this metric [12]. What happens when the energy difference

Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• ][22][23][24][25]. However, even these recent methods suffer from serious drawbacks, such as the use of precious metals often combined with sophisticated organic ligands, which makes them expensive, especially if implemented on an industrial scale. In addition, increasingly restrictive legislation

• against residual metals in manufactured goods and active ingredients stimulates the ongoing search for new metal-free solutions to the problem making this challenge even topical [26][27]. Based on the considerations mentioned above, we focused on an alternative strategy to activate the oxidation process

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• for reacting substrates, reaction conditions and transition metals used as the catalyst. This review will be helpful to the chemists in understanding the challenges associated with the reported methods as well as the future possibilities, both in the choice of substrates and catalysts. This review

• would be quite appealing to a wider range of organic chemists in academia and industrial R&D sectors working in the field of heterocyclic syntheses. In a nutshell, this review will be a guiding torch to envisage: (i) the role of various transition metals in the domain dedicated towards method

• for efficient syntheses of IPs [20]. In recent years much attention has been paid towards the exploration of transition metals (TMs) as homogeneous as well as heterogeneous catalytic system like Pd(OAc)2 [21], CuI [22], ZnO [23], ZnI2 [24], Cu(OTf)2 [25], Sc(OTf)3 [26], RuCl3 [27], [Cp*RhCl2]2 (Cp

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• isocyanides and sulfur [76] can be enhanced using various catalysts such as selenium, molybdenum, copper, rhodium [77][78][79][80][81][82] or tellurium [83] providing the isothiocyanates in excellent yields. These approaches on the other hand suffer from the use of heavy metals, toxic chalcogens and/or long