Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• study protonated forms of the oxadiazoles as reactive intermediates by means of NMR and DFT calculations. It should be noted, that the metal-catalyzed hydroarylation of C=C bonds is widely used in organic synthesis [26][27]. The most efficient catalysts for these purposes are complexes of the transition

• metals Pt [28], Au [29], Ru [30], Rh [31][32][33], Ni [34], Pd [35], and Pd/Ag [36]. However, a metal-free hydroarylation variant of C=C bonds under the action of Brønsted or Lewis superacids has been developed [37][38] and we were able to extend the scope of this reaction [24][25]. The expected reaction

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• fluorescence under UV excitation, a standard feature of bottom-up produced carbohydrate-derived CDs (Scheme 8) [39]. Whereas most synthetic CDs from glucose sources generally show a fluorescence-decay response to one or several transition metals. Surprisingly, the CDs produced in the presence of glutathione

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• activate the terminal acetylene primarily, which then undergoes a nucleophilic addition to the iminium electrophile generated from the aldehyde and the amine. Among different transition metals, copper metal has been mostly explored as the catalyst to activate the terminal acetylene, though there is a

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• -butyl esters, avoiding the use of inflammable and explosive gaseous isobutylene [35], the use of harsh conditions [36], the use of peroxides [37], the use of toxic gas such as CO or transition metals [38][39][40][41][42]. The flow process, for the direct C-tert-butoxycarbonylation of organolithiums, has

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• transition metals (In, Sc, Ce, Pr, Nd, Eu, Dy, Yb, Lu, Hf, Gd) were used, the cyclization proceeded in unsatisfactory yields and with a large number of unidentified byproducts. Cyclization of other 3-arylpropionic acids 7 led to the formation of 4,7-dimethoxy-1-indanones 8. They were used in the key step of

Adsorption of RNA on mineral surfaces and mineral precipitates

• Elisa Biondi,
• Yoshihiro Furukawa,
• Jun Kawai and
• Steven A. Benner

Beilstein J. Org. Chem. 2017, 13, 393–404, doi:10.3762/bjoc.13.42

• osmium phosphate, neither of which has been reported in mineralogy. Likewise, horizontal comparisons across the Periodic Table are problematic, even within transition metals. For example, we found that RNA binds to natural titanium dioxide (rutile, 21% in our experiments) and iron(III) oxide (Fe2O3

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• removal of a beneficial functional group. The electron-withdrawing properties of the nitrile functional group appear beneficial in a variety of reactions [1][2]. This group coordinates metal complexes and can be used as a directing group for C–H bond activation reactions catalyzed by transition metals [3

• ]. Iron-catalyzed reductive decyanation In 1982, Yamamoto et al. disclosed the C–CN bond cleavage promoted by an electron-rich cobalt complex [92]. Since that time, the activation of inert C–CN bonds by transition metals has been widely investigated. Improvements towards mild and green conditions with a

Direct arylation catalysis with chloro[8-(dimesitylboryl)quinoline-κN]copper(I)

• Sem Raj Tamang and
• James D. Hoefelmeyer

Beilstein J. Org. Chem. 2016, 12, 2757–2762, doi:10.3762/bjoc.12.272

• utilize expensive transition metal catalysts (Pd, Rh, Ir) at high loadings (typically 10 mol %), and require a large amount of strong base (typically 3 equivalents KO(t-Bu)). There has been some success using inexpensive first-row transition metals (Fe [24][25], Co [26][27][28], Ni [29][30][31][32][33

• use of ambiphilic molecules as ligands for transition metals has given rise to an important new class of catalysts [49]. In previous work from our laboratory, we prepared the intramolecular frustrated Lewis pair 8-quinolyldimesitylborane (1) and its complexes with Cu(I), Ag(I), and Pd(II) [50

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• reaction, is a non-toxic byproduct. However, the poor ability of the hydroxy moiety, as a leaving group, has limited the use of the allyl alcohols as substrates. Correlatively, some efforts have been made in this direction by the use of transition metals such as copper [6], nickel [7], ruthenium (I, II) [8

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• and trapping of an intermediate acylnitroso dienophile in the presence of transition metals (Scheme 36), e.g., [67][136][137][138][139][140][141]. b) The second approach relies on the activation of a moderately reactive arylnitroso dienophile by scandium [142] or copper [103][104] metal ions, which

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• transition metals by generating the corresponding [M(terpyridine)2]2+ or [M(terpyridine)]2+ complexes. This ability was exploited in the development of colorimetric “naked-eye” chemosensors for poisoning Hg(II) ions from drinking water in the presence of other metal pollutant competitors [43]. Therefore

Cp₂TiCl/D₂O/Mn, a formidable reagent for the deuteration of organic compounds

• Antonio Rosales and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2016, 12, 1585–1589, doi:10.3762/bjoc.12.154

• donor. Cp2TiCl, consists of titanium, one of the most abundant transition metals in the Earth’s crust [16], that can be easily prepared from commercial Cp2TiCl2 by using reductants such as Mn, Zn or Al [17][18], generating in THF, in absence of water a green solution, or a blue one in the presence of

• ] or activated halides [30] and Cp2TiCl/Mn), to intermediate titanaoxiranes (pathway B) [31][32] (obtained from carbonyl compounds and Cp2TiCl/Mn), and to late transition metals (pathway C) [33] in a process mediated by Cp2TiCl/Mn/H2O or D2O which allows for the reduction of alkenes or alkynes (Scheme

• , does not require the activation of the organometallic species with base and substoichiometric amounts of Cp2TiCl can be used. Deuteration of alkenes/alkynes [14] using Cp2TiCl/D2O/Mn and late transition metals (pathway C) was rationalized suggesting that the aqua-complex intermediate could facilitate

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• introduction of an organometallic group is necessary. The last disadvantage is overcome to some extent by the direct C–H arylation protocols [18], but usually they are catalytic and thus the resulting cross-coupling products contain traces of transition metals difficult to remove that limits their use in areas

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• pentacarbonyl metal fragments (M = Cr, Mo, W) have further proven to be effective carbene transfer agents to late transition metals in transmetalation reactions [9][10][11][12][13][14][15]. The manifold synthetic access routes to carbene complexes even allows the assembly of multicarbene and multimetal carbene

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• multicomponent reactions Transition metals, especially Pd and Cu, are well-known catalysts for multicomponent reactions. Carbopalladation reactions of allenes, alkynes and carbon monoxide are very important processes in multicomponent syntheses. Additionally, copper-catalyzed multicomponent reactions such as

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• are further classified according to whether catalysis is achieved with chiral Lewis acids, organocatalysts, or transition metals. Keywords: asymmetric catalysis; conjugate addition; enantioselective protonation; enolate; Introduction Due to their ubiquity in natural products and drugs, many

• –enantioselective protonation reactions that have been reported in the literature. These reports have been grouped by class of Michael acceptor and further subdivided by the type of catalyst system used (Lewis acids, organocatalysts and transition metals). While numerous efficient methods have been developed for

• tert-butyl ester was the reactivity significantly impacted (R2 = n-Pr, R3 = t-Bu, 36% yield, 98:2 er). Transition metals A handful of research groups have investigated transition metal-catalyzed conjugate addition–enantioselective protonation sequences involving α,β-unsaturated esters. A common theme

Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp² C–H and sp³ C–H bonds

• Nivesh Kumar,
• Santanu Ghosh,
• Subhajit Bhunia and
• Alakesh Bisai

Beilstein J. Org. Chem. 2016, 12, 1153–1169, doi:10.3762/bjoc.12.111

• oxidative coupling of two C–H bonds [also termed as cross-dehydrogenative-coupling (CDC)] in the formation of C–C bonds [11][12][13][14][15][16]. This was facilitated by the introduction of transition metals in organic synthesis providing an amazing tool to explore these oxidative coupling reactions in an

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• transition metals to affect asymmetric enyne cycloisomerization [13][14][15][16][17][18][19][20][21][22][23]..In particular, Mikami has disclosed a palladium-catalyzed asymmetric enyne cycloisomerization where a tetrahydrofuran containing a quaternary, all-carbon stereocenter is created in excellent yield

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• over the decades [1][2][3][4][5][6][7][8]. Mechanistically, the C(sp3)–H bond insertion reaction is considered to follow a concerted reaction pathway with a three-center two electron transition state (Scheme 1). Since late transition metals, typically Rh(II) complexes, are most commonly employed as the

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• organophosphorus compounds (OPC) is the direct transformation of five-membered metallacarbocycles based on transition metals to phosphacarbocycles on treatment with phosphorus dihalides. For example, a method for the direct conversion of zirconacyclopentenes [1][2][3][4] and zirconacyclopentadienes [5] to

• the proximate asymmetric centres at C-3 and С-3′. Ratios of stereoisomers were determined by HPLC method as 2:1 (see Supporting Information File 2, Figure S1). Organophosphorus compounds, including cyclic ones, are known to readily form complexes with transition metals, which are extensively studied

Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands

• Julia Wappel,
• Roland C. Fischer,
• Luigi Cavallo,
• Christian Slugovc and
• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 154–165, doi:10.3762/bjoc.12.17

• ] bearing one or two 8-quinolinolate ligands. Results and Discussion Synthesis and characterization Herein we investigate 8-hydroxyquinoline derivatives as the chelating, “pacifying” ligands. 8-Hydroxyquinoline and its derivatives are known to be excellent ligands for many transition metals [37]. They can

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• herein discussed. Recent advances in the design and syntheses reported mainly during the last three years are highlighted, with special emphasis on new trends for superior applications of these hybrid materials. Keywords: advanced materials; metallopolymers; metathesis; ROMP; transition metals

• , metallopolymers are endowed with linear, cross-linked, hyperbranched, star or dendritic polymer architectures containing metals ranging from the main groups to transition metals and lanthanides which are embedded into the main chain or appended to the side chains of the polymer [8][9][10][11]. This make-up would

• -based synthesis and applications of polymers containing transition metals in the side chain evidencing recent work published since our earlier review on this topic [34]. Metallopolymers are herein classified according to the nature of the transition metal and its binding mode to the organic moiety

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• elegant works of Lloyd-Jones and Russell on gold-catalyzed oxidative C–H arylation of simple arenes with arylsilanes have led the way to novel gold-catalyzed reactions that could not be achieved with other transition metals [68][69]. In these reactions, the oxidation of gold(I) to gold(III) is thought to

Life lessons

• Jonathan R. Nitschke

Beilstein J. Org. Chem. 2015, 11, 2350–2354, doi:10.3762/bjoc.11.256

• zirconocene-mediated macrocyclization reactions to make a series of new structures under thermodynamic control, two examples of which are shown in Scheme 1 [1][2]. This Ph.D. work gave me a taste for organic chemistry involving transition metals, and an interest in structures that form under conditions of