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Search for "ruthenium" in Full Text gives 269 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization
Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110
- alcohols revealed a matched/mismatched effect that was strongly dependent on the nature of the solvent. Keywords: asymmetric catalysis; [3.1.0] bicycles; [4.1.0] bicycles; cycloisomerization; 1,6-enyne; 1,7-enyne; ruthenium catalysis; sulfoxide; Introduction Due to their prevalence in natural products [1
- (MeCN)3PF6-catalyzed variant of the same reaction that proceeds even at room temperature [10]. The ruthenium process differs from the initially-discovered palladium reaction in that it produces cyclic 1,4-dienes exclusively; no olefin isomerization is detected (Scheme 1, path b). Moreover, ruthenium can
- mechanism. Whereas the palladium-catalyzed Alder–ene reaction proceeds through an initial hydrometallation of a palladium hydride intermediate, ruthenium is speculated to first form a ruthenacyclopentene prior to β-hydride elimination. Since the hydrogen leading to the 1,3-diene is inaccessible to the
Modular synthesis of the pyrimidine core of the manzacidins by divergent Tsuji–Trost coupling
Beilstein J. Org. Chem. 2016, 12, 1111–1121, doi:10.3762/bjoc.12.107
- additional additives to impede a possibly unfavorable amine coordination of the reactive ruthenium intermediates [51] did not improve the reaction outcome (entries 2–4). Following reports from Nolan and Prunet [52], as well as from Steinke and Vilar [53] we finally evaluated tricyclohexylphosphane oxides and
Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update
Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98
- reactions of α-olefins and styrenes with 3-hydroxy-2-oxindoles were achieved by using the ruthenium complex, giving the products as single diastereoisomers (Scheme 11) [27]. Interestingly, 1-adamantanecarboxylic acid (10 mol %) as a co-catalyst can remarkably enhance the yields from trace to >90%. A broad
- ] and PCy3 formed the ruthenium(0) complex, which then mediated the oxidative coupling of N-benzyl-protected isatin and styrene to form oxametallacycle I. The ruthenium alkoxide III was formed through two possible pathways: (a) the direct transfer hydrogenolytic cleavage of I (slow); (b) the
- protonolysis of I by adamantanecarboxylic acid, followed by exchange of the carboxylate II with 3-hydroxy-2-oxindole (rapid). β-Hydride elimination of III generated ruthenium hydride IV and N-benzylisatin. Subsequent C–H reductive elimination of IV produced the product and regenerated the ruthenium(0) complex
A cross-metathesis approach to novel pantothenamide derivatives
Beilstein J. Org. Chem. 2016, 12, 963–968, doi:10.3762/bjoc.12.95
- -methoxybenzaldehyde acetal protecting group in 9 is believed to tie back the alcohols and prevent them from coordinating and deactivating the ruthenium catalyst. When testing the scope of the metathesis reaction with 9, a variety of partners were chosen, including not only acrylic acid (10a), but also 2-vinylpyridine
Enantioselective carbenoid insertion into C(sp3)–H bonds
Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87
- promote the formation of a specific enantiomer. The search for the best balance of these properties of the carbenoid intermediates was also sought through the use of different metals such as copper [3], rhodium [4], iron [5], ruthenium [6], iridium [7], osmium [8], and others. From these, copper and
- expensive than the use of other metals such as rhodium, copper and ruthenium, for example. Efforts should be directed toward the development of simpler ligands specially those based on inexpensive chiral building blocks like amino acids and sugars. The examples of works focused on copper-based catalysts are
Creating molecular macrocycles for anion recognition
Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60
- triazole nitrogens but not past the pyridine with the steric protection provided by a CH group (see the red arrows in Figure 4c for the overlay of the two ligands). The ruthenium complex showed intermolecular π stacking of ligands on neighboring complexes in the solid state; yet terpyridine analogs did not
The aminoindanol core as a key scaffold in bifunctional organocatalysts
Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50
- disulfides and sulfides, which are involved in the synthesis of ligands and pharmaceutical chiral synthetic precursors [1][2] and in (b) the transfer-hydrogenation reaction catalyzed by bifunctional chiral ruthenium complexes, employed in the synthesis of peptide mimics with an interesting
Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands
Beilstein J. Org. Chem. 2016, 12, 154–165, doi:10.3762/bjoc.12.17
- 10.3762/bjoc.12.17 Abstract A straightforward synthesis utilizing the ring-opening metathesis polymerization (ROMP) reaction is described for acid-triggered N,O-chelating ruthenium-based pre-catalysts bearing one or two 8-quinolinolate ligands. The innovative pre-catalysts were tested regarding their
- towards the control of polymer functionalization and living or switchable polymerizations. Keywords: acid; activation by acid; metathesis; polymer; quinolin; ruthenium; triggerable; Introduction The modulation of the activity of enzymes by chemical triggers, e.g., by allosteric binding is ubiquitous in
- insensitive as possible to any other potentially present chemical, most importantly oxygen and water [30]. Particularly for the latter reason ruthenium based latent initiators play the most important role in literature [24][31][32][33]. Last but not least, bearing in mind changes in activity or levels of
Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports
Beilstein J. Org. Chem. 2016, 12, 5–15, doi:10.3762/bjoc.12.2
- , University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland 10.3762/bjoc.12.2 Abstract An ammonium-tagged ruthenium complex, 8, was deposited on several widely available commercial solid materials such as silica gel, alumina, cotton, filter paper, iron powder or palladium on carbon. The resulting
- catalysts were tested in toluene or ethyl acetate, and found to afford metathesis products in high yield and with extremely low ruthenium contamination. Depending on the support used, immobilised catalyst 8 shows also additional traits, such as the possibility of being magnetically separated or the use for
- metathesis and subsequent reduction of the obtained double bond in one pot. Keywords: catalysis; immobilisation; N-heterocyclic carbenes; olefin metathesis; ruthenium; Introduction Over the past decade olefin metathesis has undergone a grand development. The design of stable and active ruthenium-based
New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand
Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300
- of organic chemistry since 1992, when Grubbs discovered the first well-defined ruthenium catalyst [2]. Nearly 400 ruthenium heterocyclic carbene-coordinated olefin metathesis catalysts were prepared until 2010 [3]. Since 2011, when Grubbs reported the synthesis of a Z-selective catalyst [4], several
- the above-mentioned moieties. The ruthenium complexes 4–6 (Figure 2) that we reported earlier appeared to be the so-called dormant catalysts. Their activity in RCM reactions was low at room temperature and higher at elevated temperature [21]. In catalyst 7 the chelating oxygen atom was provided by the
- coordination to the ruthenium atom, and finally, facilitates the initiating process. In the new catalyst 9, which is modified in the NHC ligand, different effects are responsible for its activity. According to Grubbs [31], catalyst 1 is able to react with α,β-unsaturated carbonyl compounds to form an enoic
Recent advances in metathesis-derived polymers containing transition metals in the side chain
Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296
- the polymerization time (Scheme 6). In this process, the ruthenium initiator proved to well tolerate the dicobalt hexacarbonyl complex embedded in the monomer. By controlled heating of the cobalt-containing block copolymers, robust, room temperature ferromagnetic (RTF) materials have been obtained. By
- , followed by functionalization of the latter with n-butylamine to yield 17b, and finally this organic polymer hydroaminated the ethynyl cobalticenium to produce 17 (Scheme 7B). Both protocols embody an elegant and original ROMP-based access to cobalticenium-containing polyelectrolytes. Ruthenium-, iridium
- -, osmium- and rhodium-containing polymers ROMP syntheses of homopolymers and block copolymers bearing bipyridine–ruthenium complexes starting from norbornene or oxanorbornene functionalized with Ru complexes have been reported by several authors [55][56]. In these investigations it was revealed that the Ru
Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism
Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275
- , only one product was observed in each case. Cenini et al. have reported that both cycloadduct and ene product are formed in the ruthenium-catalysed reaction of nitrobenzene (an alternate route to a nitrosobenzene intermediate) with isoprene [57]. As mentioned above, isoprene produces two different
Diversity-oriented synthesis of analogues of the novel macrocyclic peptide FR-225497 through late stage functionalization
Beilstein J. Org. Chem. 2015, 11, 2487–2492, doi:10.3762/bjoc.11.270
- )(trichlorohexylphosphine)ruthenium, G-II] smoothly effected the desired transformation within a short period of time. Compound 14 was obtained as a single (E)-isomer, as expected. Saturation of the double bond in the latter furnished nor-FR225497 (15) in an overall yield of ≈70% over two steps from template 13. We opted
Efficient synthetic protocols for the preparation of common N-heterocyclic carbene precursors
Beilstein J. Org. Chem. 2015, 11, 2318–2325, doi:10.3762/bjoc.11.252
- just a single example, NHC ligands played a crucial role in the development of highly efficient ruthenium initiators for olefin metathesis and related reactions [18][19][20][21]. Lately, these divalent carbon species have also emerged as powerful nucleophilic organocatalysts for polymer chemistry [22
Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics
Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241
- deactivation caused by amino derivatives will be first presented and discussed. RCM and CM involving alkenes possessing N-heteroaromatics will be then successively examined [38]. Review Mechanistic insights into amine-induced catalyst deactivation Recently, intensive studies dealing with ruthenium catalyst
- deactivation in metathesis have been published, most of them focusing on the GII catalyst [39][40][41][42][43]. In 2007, Grubbs et al. examined the decomposition pathways of various ruthenium methylidenes using NMR spectroscopy [44]. The methylidenes 1 and 2 derived from GI and GII had a half-life of 40 min
- methylidene intermediates 3 and 4 to give CH3PCy3+Cl− and inactive ruthenium complexes. Similar observations were made in the absence or in the presence of ethylene in the reaction medium (Scheme 1). Similar studies concerning the Grubbs–Hoveyda II catalyst were difficult due to the instability of the
Computational study of productive and non-productive cycles in fluoroalkene metathesis
Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232
- initiating ruthenium precatalysts [12][13]. A theoretical approach has been also employed in attempts to gain a better insight into the complex structure of intertwined productive and non-productive catalytic cycles of alkene metathesis [14]. In contrast to the older computations, new publications also
- concentrated on the side chain of the vinyl group [24][25][26][27] or applications of 2-fluoroalkenes [28][29][30]. As an exception, the reaction of the Grubbs 2nd generation catalyst with 1,1-difluoroethene gave an isolable difluoromethylene-containing ruthenium complex with very poor catalytic activity [31
- with selected fluoro- and chloroalkenes has been studied and the higher stability of a ruthenium intermediate containing a difluoromethylene ligand has been emphasized [36][37]. A complete mechanism of alkene metathesis including initiation, productive and non-productive cycles represents a highly
Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions
Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225
- determination of the ruthenium content was performed by inductively coupled plasma mass spectrometry (ICP–MS) by the Institute of Analytical Chemistry (ICT, Prague, Czech Republic). Catalyst preparation Immobilization of HGIIN+X− complexes was performed by stirring a mixture of complex and support in CH2Cl2 at
Olefin metathesis in air
Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221
- been made to render catalysts more stable and yet more functional group tolerant. This review summarizes the major developments concerning catalytic systems directed towards water and air tolerance. Keywords: air stability; catalysis; olefin metathesis; RCM; ROMP; ruthenium; Introduction Transition
- hopefully raise the awareness of the significant tolerance of standard metathesis catalysts to these conditions. Review Well-defined ruthenium catalysts Although well-defined early transition metal-based catalysts formed the basis of early metathesis reactions and can be thought of as the forefathers of
- , late transition metals, which do not exhibit high oxophilicity, appeared as the most promising candidates for reactions performed in air. Indeed in 1988, Grubbs and Novak reported that not only ruthenium was an interesting candidate for olefin metathesis, but also that reactions were successfully
Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions
Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212
- , OR 97203, USA 10.3762/bjoc.11.212 Abstract Three new ruthenium alkylidene complexes (PCy3)Cl2(H2ITap)Ru=CHSPh (9), (DMAP)2Cl2(H2ITap)Ru=CHPh (11) and (DMAP)2Cl2(H2ITap)Ru=CHSPh (12) have been synthesized bearing the pH-responsive H2ITap ligand (H2ITap = 1,3-bis(2’,6’-dimethyl-4’-dimethylaminophenyl
- the polymerization process. Furthermore, the coagulate content for all experiments stayed <2%. This represents an unprecedented efficiency in emulsion ROMP based on hydrophilic ruthenium alkylidene complexes. Keywords: activation; aqueous catalysis; emulsion; olefin metathesis; polymerization
- ; ruthenium; Introduction The vast application spectrum of Ru-based olefin metathesis has provided a powerful synthetic tool for the organic [1][2][3] and polymer chemist [4][5][6][7][8] alike. The catalysts’ high tolerance towards functional groups, air and moisture makes them attractive to be used in
New aryloxybenzylidene ruthenium chelates – synthesis, reactivity and catalytic performance in ROMP
Beilstein J. Org. Chem. 2015, 11, 1910–1916, doi:10.3762/bjoc.11.206
- Patrycja Zak Szymon Rogalski Mariusz Majchrzak Maciej Kubicki Cezary Pietraszuk Adam Mickiewicz University in Poznań, Faculty of Chemistry, Umultowska 89b, 61-614 Poznań, Poland 10.3762/bjoc.11.206 Abstract New phenoxybenzylidene ruthenium chelates were synthesised from the second generation
- ) and a single selected norbornene derivative. Keywords: chemoactivation; latent catalysts; metathesis; ROMP; ruthenium; Introduction Olefin metathesis is nowadays one of the most important methods for the formation of carbon–carbon bonds in organic and polymer chemistry [1][2]. The availability of
- well-defined ruthenium-based catalysts, showing a number of desirable features such as tolerance of functional groups, moisture and air, has significantly expanded the scope and application of this process regardless of dynamic advancement in the development of ruthenium-based metathesis catalysts
Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate
Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204
- allyl acetate promoted by different ruthenium alkylidene catalysts were studied. The stereochemical outcome of the reactions was established. The issues concerning chemo- (ROCM vs ROMP), regio- (1-2- vs 1-3-product formation), and stereo- (E/Z isomerism) selectivity of reactions under various conditions
- ROCM reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-en-2-carbonitrile (1 and 2, respectively) with allyl acetate (3) or allyl alcohol (4) catalyzed by several commercially available ruthenium catalysts ([Ru]1–6, Figure 1). To the best of our knowledge there is no example of a ROCM reaction of 7
- . Furthermore, less complex mixtures of products were formed and they were easier to separate from the ROMP products. 7-Oxanorbornenes 1 and 2 were treated with olefin 3 or 4 in the presence of ruthenium catalysts [Ru]1–6 (Figure 1) to afford mixtures of tetrahydrofurans 5–12 (Scheme 2). The mixtures were
Profluorescent substrates for the screening of olefin metathesis catalysts
Beilstein J. Org. Chem. 2015, 11, 1886–1892, doi:10.3762/bjoc.11.203
- . To demonstrate the validity of the approach, four commercially available ruthenium-metathesis catalysts were evaluated in six different solvents. The results from the fluorescent assay agree well with HPLC conversions, validating the usefulness of the approach. Keywords: fluorescence; microplate
Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks
Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201
- compounds. The resulting cross metathesis products were hydrogenated in a tandem fashion employing the residual ruthenium from the metathesis step as the hydrogenation catalyst. Interestingly, the epoxide ring remained unreactive toward this hydrogenation method. The saturated compound resulting from the
- cross metathesis of 1 with methyl acrylate was transformed by means of nucleophilic ring-opening of the epoxide to furnish a diol, an alkoxy alcohol and an amino alcohol in high yields. Keywords: cross metathesis; epoxide; ruthenium catalysts; tandem reactions; Introduction Catalytic carbon–carbon
- necessary to ensure high conversion. Reactions were carried out in dimethyl carbonate (DMC), a solvent compatible with ruthenium olefin metathesis catalysts [28] while being much greener than toluene or dichloromethane commonly used in such reactions [29]. Based on our previous results and observations in
Recent applications of ring-rearrangement metathesis in organic synthesis
Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199
- % yield [51]. The regioselective formation of 240 may be attributed to the facile formation of a Ru–carbene intermediate where the metal participates on the side opposite to that of the methyl ester and thereby minimizing the steric crowding between ruthenium and carbonyl oxygen of an ester functionality
- RRM process and this activity will continue with more vigour in the future. Ruthenium alkylidene catalysts used in RRM processes. General representation of various RRM processes. A general mechanism for RRM process. RRM of cyclopropene systems. RRM of cyclopropene with catalyst 2. (i) catalyst 2 (2.5
Nitro-Grela-type complexes containing iodides – robust and selective catalysts for olefin metathesis under challenging conditions
Beilstein J. Org. Chem. 2015, 11, 1823–1832, doi:10.3762/bjoc.11.198
- vicinity of ruthenium related to the presence of iodides ensures enhanced catalyst stability. The benefits are most apparent under challenging conditions, such as very low reaction concentrations, protic solvents or with the occurrence of impurities. Keywords: green solvents; macrocyclization; metathesis
- ; ruthenium; Introduction Olefin metathesis (OM) is a mild and versatile catalytic method which allows the formation of carbon–carbon double bonds [1]. Understanding the key events in ruthenium-catalyzed olefin metathesis [2] and developing efficient and selective catalysts [3] provides opportunities for
- interest. Currently, the second generation Hoveyda-type catalysts, such as HII [4], A [5], B [6], and C [7] are considered to be the most versatile tool for OM (Figure 1). Modifications of ligands permanently bound to the ruthenium center appear to be the most efficient methods for altering the catalyst
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