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

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• ][16]. It should be especially emphasized that intermolecular reactions of phosphorylallenes with arenes have not been yet achieved. In general, intermolecular hydroarylation of allenes has been developed for reactions catalyzed by complexes of various metals [17], such as Pd [18][19][20], Pt [21], Au

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• the CD OH groups. The formation of CD alkali salts always results in residual water when no metals or metal hydrides are used. The safer use of the hydroxides, in comparison with alkali metals or their hydrides, considerably outweighs the purification costs. Scheme 1 shows a general reaction scheme

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• preformed metal phosphate is critical to effect catalysis and chiral induction. Among the metals screened, Fe(III) phosphate gave the optimal results in terms of both activity and enantioselectivity (79% yield, 35% ee, Table 1, entry 5). Fe(III)-based bisphosphate anions were also tested. To our delight

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides

• Madhu Babu Tatina,
• Xia Mengxin,
• Rao Peilin and
• Zaher M. A. Judeh

Beilstein J. Org. Chem. 2019, 15, 1275–1280, doi:10.3762/bjoc.15.125

• . The majority of the reported catalysts are metal-based, and in pharmaceutical manufacturing, traces of metals pose a major challenge for their removal to acceptable limits. Therefore, the discovery of efficient, metal-free and mild catalysts for the Ferrier rearrangement is still challenging and

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• identifying Fe3+. Figure 3b shows the fluorescence intensity change of CN-dots in the presence of metal ions. The experimental results suggested that there are several metals ions that could simultaneously quench the fluorescence of CN-dots, further indicating that CCDs is superior to CN-dots in the selective

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• other processes, quenching the photoisomerization; (v) the energy storing MOST materials have to utilize light in the visible range of the spectrum; (vi) it will be a crucial benefit for the MOST technology, if toxic and precious metals are avoided. Focusing on environmentally friendly MOST system is an

Molecular recognition using tetralactam macrocycles with parallel aromatic sidewalls

• Dong-Hao Li and
• Bradley D. Smith

Beilstein J. Org. Chem. 2019, 15, 1086–1095, doi:10.3762/bjoc.15.105

• been noted before as a factor that effects [2]rotaxane dynamics [56][63]. 3.3. Precious metals complexes The electrostatic interior surface of the amphiphilic tetralactam cavity is complementary to the electrostatic surface of the core of a squaraine dye which has a partial positive charge at the

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• (terpyridines; Figure 1c) ligands [49]. The model systems depicted in Figure 1 are constructed using metals like Pd(II) or Pt(II) ions for square planar geometry, Cu(I) or Ag(I) ions for tetrahedral geometry and Co(II)/Cu(II)/Fe(II)/Zn(II)/Hg(II) for octahedral organization [50]. In Figure 2, Busch’s first

• ) and ethylenediamine (5). Subsequently, to the same pot appropriate metals were added to obtain the respective complexes 7 [55]. In 2002, Otera and co-workers reported the formation of some supramolecular self-assembled structures which was found to be faster under solvent-free mechanochemical

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• blue, O red, S yellow, metals flesh (Zn, Cd) or green (Ni)). Space filling representation of the packing of two symmetry-related [Zn2L(μ-azo-NMe2)]+ cations in crystals of 5·1.5MeCN. The ClO4− anions and solvate molecules are omitted for clarity. Structure of the [Cd2L(μ-azo-NMe2)]+ cation in crystals

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• prepared and their binding properties toward sodium and potassium ions were studied in addition to transition metals. Sakata et al. reported the syntheses and characterization of nickel(II), copper(II) [25] and oxovanadium(IV) [26] complexes of crown ether-annulated DBTAAs, which caused dimerization in the

• satisfactory 26–28% isolated yields and fully characterized based on HR-ESIMS, FTIR-ATR, 1H and 13C NMR spectroscopy and elemental analysis. These novel receptors are expected to bind both the transition, alkali and alkaline-earth metals, and also, after DBTAA subunit metalation the whole ion pairs. The

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• as cell imaging tools [31][32], biosensors and sensors for detection of heavy metals [33]. The tendency of these structures to form hydrogen bonds, to respond to medium effects (solvatochromism) [34] and to certain impurities (e.g., coordination complexes with metal ions) make these compound classes

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• thiols (Scheme 1) [17][18][19][20][21], other methodologies employing different sulfur sources such as disulfides or silylsulfides have been described, which most of them involves metals, e.g., indium [22], copper [23], mercury [24], or organocatalysts [25]. β-Ketosulfides, in addition, play an important

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• transition metals, Lewis acids, and organocatalysts has been productively utilized in asymmetric transformations [7][8][9], cross-couplings [10][11][12], and oxidative decarboxylation reactions [13][14], among others. The use of a cocatalyst to control these photochemical transformations enables reactions

Synthesis of 1,2-divinylcyclopropanes by metal-catalyzed cyclopropanation of 1,3-dienes with cyclopropenes as vinyl carbene precursors

• Jesús González,
• Alba de la Fuente,
• María J. González,
• Laura Díez de Tejada,
• Luis A. López and
• Rubén Vicente

Beilstein J. Org. Chem. 2019, 15, 285–290, doi:10.3762/bjoc.15.25

• reactions [17]. Other metals capable of promoting both carbene generation from cyclopropenes and cyclopropanation reactions were also evaluated. Interestingly, when [Rh2(OAc)4] (1.0 mol %) was employed, compound 3a was isolated in 71% yield, a slightly lower value when compared to ZnCl2, but more