Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• first palladium-catalyzed arylation of thiols was reported by Migita and co-workers in 1980 [5], and soon after Cristau and co-workers developed a nickel-catalyzed route for C–S cross-coupling reactions [6]. Other metals such as copper [7], cobalt [8], iron [9], rhodium [10], manganese [11], indium [12

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

• reaction was facilitated at room temperature by N-hydroxyphthalimide (NHPI) and cobalt acetate (Co(OAc)2) as catalysts in acetonitrile (Scheme 20). The reaction followed a free radical mechanism as exemplified by the oxidative dehydrogenation of DHPs. The initial step involved the formation of the

• (Scheme 41). The catalytic system comprised of an octahedral [Ru(phd)3]2+ catalyst along with cobalt-N,N´-bis(salicylidene)-1,2-phenylenediamine [Co(Salophen)] as a redox co-catalyst. The reaction occurs aerobically under mild conditions (Scheme 41) [100]. Our final example demonstrated the utility of

• , phd = 1,10-phenanthroline-5,6-dione. Oxidative dehydrogenation with Flavin mimics. o-Quinone based bioinspired catalysts for the synthesis of dihydroisoquinolines. Cobalt-catalyzed aerobic dehydrogenation of Hantzch 1,4-DHPs and pyrazolines. Mechanism of cobalt-catalyzed aerobic dehydrogenation of

Unpredictable cycloisomerization of 1,11-dien-6-ynes by a common cobalt catalyst

• Abdusalom A. Suleymanov,
• Dmitry V. Vasilyev,
• Valentin V. Novikov,
• Yulia V. Nelyubina and
• Dmitry S. Perekalin

Beilstein J. Org. Chem. 2017, 13, 639–643, doi:10.3762/bjoc.13.62

• cycloisomerization in the presence of the cobalt catalytic system CoBr2/phosphine ligand/Zn/ZnI2 giving cyclohexene, diene or cyclopropane structures depending on the type of the phosphine ligand. This unpredictable behaviour suggests that, although the availability of the cobalt catalytic system is appealing, the

• development of well-defined catalysts is desirable for further progress. Keywords: catalysis; cobalt; cyclization; enynes; ligands; Introduction Metal-catalyzed reactions of enynes represent an atom- and step-economical route to complex organic molecules with a broad range of functionalities [1][2][3][4

• polycycles [8][11][12][13] (Scheme 1). However, all these transformations require expensive noble metal catalysts with rather sophisticated ligands. Therefore, the development of a cheap catalyst for such reactions is highly desirable. Over the last decade the application of the cobalt catalytic system CoBr2

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

• ], mercury [26], cobalt [27], iridium [28], ruthenium [29], indium [30] etc. Other methods towards the synthesis of propargylamine include: alkynylation of imine [31][32][33], enamine [34], and Csp³–H bonds adjacent to N-atoms [35][36]. In the A3 coupling, the role of the metal catalyst is believed to

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

• ]. 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

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• precursor in this total synthesis. The subsequent cobalt-catalyzed cyclization reaction proceeded chemoselectively in the presence of the alkyne moiety and provided the trans-disubstituted THF 22 in high yield [69][70][71]. Finally, building block 23, one important fragment in the total synthesis of

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• cationic dyes. Zhang et al. [4] studied the removal of cobalt and 1-naphthol onto magnetic nanoparticles containing cyclodextrin and iron and Yang et al. [5] proposed a new nanocomposite adsorbent for the simultaneous removal of organic and inorganic substances from water. Here, we propose to use a single

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

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

• (PdNPs) affording highly active catalysts for Suzuki–Miyaura coupling reactions. Cobalt-containing polymers The incorporation of other late transition metals such as cobalt into polymers soon emerged as an efficient and rapid method for the production of nanostructured materials of scientific and

• application of metallopolymers as heterogeneous macromolecular catalysts for living radical polymerizations, Tang et al. [51] produced the cobalt-containing polymer 10 by ROMP of the norbornene monomer 9, derivatized with triazolyl and cyclopentadienylcobalt-1,3-cyclopentadiene moieties (Scheme 5). The

• triazolyl unit was first attached to the η4-cyclopentadiene CpCo(I) complex by click reaction of the corresponding alkyne precursor and then the triazolyl-Co scaffold was incorporated into the norbornene monomer 9 by conventional esterification. It is important to note that the cyclopentadienyl-cobalt-1,3

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• developed for the production of cyclic carbonates [7][8][9] and polycarbonates [10][11] from carbon dioxide and epoxides, the most developed and privileged set of catalysts are based on Lewis acidic metal–salen complexes. In particular, cobalt(III) and chromium(III) complexes were found to be highly

Surprisingly facile CO₂ insertion into cobalt alkoxide bonds: A theoretical investigation

• Willem K. Offermans,
• Claudia Bizzarri,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 1340–1351, doi:10.3762/bjoc.11.144

• calculations to elucidate the reaction step of CO2 insertion into cobalt(III)–alkoxide bonds, which is also the central step of metal catalysed carboxylation reactions. It was found that CO2 insertion into the cobalt(III)–alkoxide bond of [(2-hydroxyethoxy)CoIII(salen)(L)] complexes (salen = N,N”-bis

• , a linear Brønsted–Evans–Polanyi relationship was found between the activation energy and the reaction energy. Keywords: activation; alkoxide; carbon dioxide; cobalt; insertion; salen; Introduction Carbon dioxide (CO2) has been known to be an attractive carbon source for decades [1][2][3][4][5][6

• – [13][14][15][16][17][18] and cobalt–salen complexes [19][20][21][22] and heterogeneous double metal cyanide (DMC) catalysts [11][23][24][25][26]. In comparison, industrially well-established catalysts are available to accelerate the production of cyclic carbonates [27][28][29]. As the CO2-based

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• ] have reported the synthesis of various pyridinophanes by a [2 + 2 + 2] cycloaddition reaction mediated by a cobalt catalyst (Scheme 51). To this end, different bisalkynes 271 were reacted with p-toluenenitrile (295, 1 mol equiv) in 1:1 ratio to obtain [2,4]pyridinophane 296 and [2,5]pyridinophane 297

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• % with cobalt tris(bipyridine)-based redox mediator. With iodide/triiodide as redox shuttle, both devices based on dye 1 and dye 2 showed higher photocurrent densities of 9.26 mA cm−2 and 12.26 mA cm−2, respectively. However, they showed lower photovoltages of 485 mV and 493 mV. As a result, in the

• . The composition of the cobalt complex-based electrolyte of this study is 0.2 M [Co(bpy)3][B(CN)4]2, 0.05 M [Co(bpy)3][B(CN)4]3, 0.1 M lithium bis(trifluoromethanesulfonyl)imide, 0.5 M 4-tert-butylpyridine in acetonitrile. The composition of the iodine-based electrolyte is 1-methyl-3-propylimidazolium

CO₂ Chemistry

• Thomas E. Müller and
• Walter Leitner

Beilstein J. Org. Chem. 2015, 11, 675–677, doi:10.3762/bjoc.11.76

• ]. Activation of carbon dioxide by inserting it into metal-alkoxide bonds allows for subsequent applications in polymer synthesis such as the copolymerisation of carbon dioxide with epoxides and other co-monomers [11]. Here, the catalysis with cobalt complexes still presents surprising effects [12]. More

Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption

• Dominik Schmitt,
• Carolin Regenbrecht,
• Marius Hartmer,
• Florian Stecker and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 473–480, doi:10.3762/bjoc.11.53

• formation of vanillin (1) and a novel as well as viable work-up concept exploiting strongly basic anion exchange resins. As renewable feedstock we employed alkaline lignin solutions. Alloys of cobalt and nickel as anodic material are suitable forming in situ electrochemically active MO(OH) coatings. Despite

Copper-catalyzed cascade reactions of α,β-unsaturated esters with keto esters

• Zhengning Li,
• Chongnian Wang and
• Zengchang Li

Beilstein J. Org. Chem. 2015, 11, 213–218, doi:10.3762/bjoc.11.23

• conjugate reduction of the α,β-unsaturated diester with newly generated copper hydride, followed by aldol reaction to yield the key intermediate alkoxide A, which is subjected to further lactonization to form the lactone. Lam’s group has furnished a cobalt-catalyzed conjugate reductive aldolization

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• 10.3762/bjoc.11.18 Abstract The cobalt(I)-catalysed 1,4-hydrovinylation reaction of allyloxytrimethylsilane and allyl alcohol with substituted 1,3-dienes leads to hydroxy-functionalised 1,4-dienes in excellent regio- and diastereoselective fashion. Those 1,4-dienols can be converted into tetrahydrofuran

• ; Introduction The reaction of terminal alkenes with 1,3-dienes under cobalt catalysis results in 1,4-dienes in a 1,4-hydrovinylation reaction. Besides cobalt, also other transition metals were described to undergo such transformations [1][2][3][4]. However, only for the cobalt-catalysed reactions a regiodiverse

• ) [46][47][48][49][50][51] or to consume the halonium ions in situ in follow-up reactions inside the cell [52]. Accordingly, we envisaged the generation of suitable starting materials via a cobalt-catalysed hydrovinylation reaction and investigated their in situ conversion via electrochemically

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• ]. The 2-aminopyridine-1-oxide directing group was used in a rare example of a cobalt-catalyzed oxidative alkoxylation of arenes 66 and alkenes 67 to afford products 68 and 69 under mild contitions [69] (Scheme 14). The directing group can be removed to obtain the corresponding benzoic acid 71 from the

• the presence of oxidants based on manganese, cobalt, and cerium [197]. The best results were achieved with the use of Mn(OAc)3 and the Co(OAc)2(cat)/KMnO4 system (Scheme 43). The yields of products 206 were as high as 94%. It is supposed that the oxidant serves two functions: the generation of N-oxyl

• or their hetero analogues, as well as for the generation of tert-butyl peroxide radicals, which react with this complex to give coupling products 214 (Scheme 44). The related peroxidation reactions with hydroperoxides (t-BuOOH, PhMe2COOH) in the presence of transition metal salts (cobalt, manganese

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

• cobalt complexes [133][134][135][136][137]. Similar to what was mentioned above for aromatic ketones, benzylic chlorides can also be converted to 2-arylpropionic acids (Scheme 18), with applications in the pharmaceutical industry, mainly as NSAIDs. Here too, some articles described the use of ionic

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• differs from that of the only other reported trans-[RhH(CO)3L] complex (where L is a bulky phosphoramidite), the observed three carbonyl bands (2055 (sh), 2022 (w) and 1998 (s) cm−1) being here spread over a larger frequency range [31]. Note that the related cobalt complex trans-[CoH(CO)3(PCy3)] displays

Building complex carbon skeletons with ethynyl[2.2]paracyclophanes

• Ina Dix,
• Lidija Bondarenko,
• Peter G. Jones,
• Thomas Oeser and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 2013–2020, doi:10.3762/bjoc.10.209

• triple bonds under the influence of a cobalt catalyst such as CpCo(CO)2 has been observed many times, notably by the Vollhardt group [12]. In our case, however, the process is not complete. Rather than yielding the expected biphenylenophane 27, the reaction stops at the stage of the cyclobutadiene

• last step is prohibitive. Instead it prefers the isomerization to the isolated CpCo-complex 26. Compound 26 was identified by its spectroscopic data (see Supporting Information File 1) and also by a single-crystal X-ray analysis. The result is displayed in Figure 6. The cobalt complex 26 shows

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts

• Jong Yeob Jeon,
• Seong Chan Eo,
• Jobi Kodiyan Varghese and
• Bun Yeoul Lee

Beilstein J. Org. Chem. 2014, 10, 1787–1795, doi:10.3762/bjoc.10.187

• -transition temperature (48 °C) than the CO2/PO alternating copolymer (40 °C). Keywords: carbon dioxide; CO2 chemistry; cobalt complex; phthalic anhydride; propylene oxide; terpolymerization; Introduction Carbon dioxide (CO2) can be utilized to prepare aliphatic polycarbonates through coupling reactions

An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism

• Carla I. Nieto,
• Pilar Cabildo,
• M. Ángeles García,
• Rosa M. Claramunt,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2014, 10, 1620–1629, doi:10.3762/bjoc.10.168

• relevant drugs (fungicides, anthelmintics, antiulcerative, antiviral,…) [2][3] are also part of some natural products (the most prominent benzimidazole compound in nature is N-ribosyl-5,6-dimethylbenzimidazole, which serves as an axial ligand for cobalt in vitamin B12) and have interesting ferroelectric

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• ; cobalt complex; metalloradical catalysis; organophosphorus; phosphoryl azide; Introduction Aziridines, the smallest three-membered nitrogen-containing heterocycles, are highly valuable heterocyclic compounds that are widely used in organic synthesis and pharmaceuticals [1][2]. As a result, tremendous

• environments toward the cobalt metalloradical center, but also function as potential donors to engage in hydrogen bonding with acceptors located at the nitrene moiety in the Co(III)–nitrene radical intermediate [18][35][36]. These secondary hydrogen bonding interactions are expected to lower the energy barrier

• the porphyrin ring are also omitted in (B). Structures of D2-symmetric chiral cobalt(II) porphyrins. [Co(TPP)]-catalyzed olefin aziridination with DPPA. [Co(P1)]-catalyzed asymmetric olefin aziridination with DPPA. Optimization of catalytic aziridination of styrene with phosphoryl azides by Co(II

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• catalysis (Table 16) [244]. Besides copper(I) iodide several other copper salts effectuated the reaction albeit in lower yields as did silver(I) iodide, palladium(II) chloride and platinum(II) chloride. Other transition metal catalysts such as gold(I) chloride, nickel(II) chloride and cobalt(II) chloride