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

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• ]. Synthesis of (1,3-bis(2’,6’-dimethyl-4’-dimethylaminophenyl)-2-dihydroimidazolidinylidene)dichloro(phenylthiomethylene)(tricyclohexylphosphine)ruthenium(II) (PCy3)Cl2(H2ITap)Ru=CHSPh (9): H2ITap∙HCl (567 mg, 1.41 mmol) and KOt-Bu (180 mg, 1.61 mmol) were heated to 80 °C in heptane (120 mL) for 90 min. After

• [31P13C] = 14.9 Hz), 30.0 (s), 28.5 (d, 2J[31P13C] = 10.1 Hz), 27.2 (s, PCy3); 31P {1H} NMR (121.4 MHz, C6D6, 20 °C) δ 23.4 (s); Anal. calcd for C44H58Cl2N8Ru: C, 60.68; H, 6.71; N, 12.87; found: C, 60.21; H, 6.77, N, 12.27. Recovery of bis(tricyclohexylphosphine)dichloro(phenylthiomethylene)ruthenium(II

• ’-dimethyl-4’-dimethylaminophenyl)-2-dihydroimidazolidinylidene)bis(4-dimethylaminopyridine)dichloro(phenylthiomethylene)ruthenium(II) (DMAP)2Cl2(H2ITap)Ru=CHSPh (12): 4-Dimethylaminopyridine (DMAP, 412 mg, 3.38 mmol) was added to a slurry of (PCy3)Cl2(H2ITap)Ru=CHSPh (9, 1.237 g, 1.32 mmol) in tert-butyl

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

• cycloaddition. Direct catalytic carboxylation of aliphatic compounds and arenes by rhodium(I)– and ruthenium(II)–pincer complexes, respectively. Insertion of carbon dioxide into a metal–oxygen bond via a cyclic four-membered transition state. R is either an aliphatic or aromatic group. Facile CO2 uptake by zinc

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• ethidium bromide–ruthenium(II) complex also proved to be an imaging probe whose fluorescence intensity and lifetime changes substantially in the presence of RNA [85], thus supporting a strategy of phenanthridinium incorporation into the heterogenic two-chromophore system. Phenanthridines are rarely

Direct C–H trifluoromethylation of di- and trisubstituted alkenes by photoredox catalysis

• Ren Tomita,
• Yusuke Yasu,
• Takashi Koike and
• Munetaka Akita

Beilstein J. Org. Chem. 2014, 10, 1099–1106, doi:10.3762/bjoc.10.108

• a CF3 group into diverse skeletons has become a hot research topic in the field of organic synthetic chemistry [7][8][9][10][11][12]. Recently, radical trifluoromethylation by photoredox catalysis [13][14][15][16][17][18][19][20][21][22][23] with ruthenium(II) polypyridine complexes (e.g., [Ru(bpy)3

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• % yields. 2,4,6-Triphenylpyrylium tetrafluoroborate was used as the sensitizer for singlet oxygen generation (Scheme 54) [301]. It was found that tris(bipyrazyl)ruthenium(II) [(Ru(bpz)3(PF6)2] is an excellent photocatalyst for the synthesis of 1,2-dioxanes by aerobic photooxygenation of α,ω-dienes [302

Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes

• Amaresh Mishra,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2013, 9, 866–876, doi:10.3762/bjoc.9.100

• stabilities, and tunability of the excited-state energies [9]. Additionally, they can be employed as energy donor or acceptor units in electronic energy transfer processes [10]. In particular, ruthenium(II) polypyridine complexes have been extensively studied and represent an area of widespread interest that

• )2]2+ complex (Δλem = 41 nm) compared to the parent [Ru(tpy)2]2+ (see Table 1) [48]. Recently, Andvincula et al. also reported a large red-shift (Δλem = 165 nm) of the 3MLCT emission for the ruthenium(II)-cored phenanthroline-oligothiophene dendrimer compared to the parent phenanthroline complex [51

• ; found: C, 62.02; H, 4.58; N, 3.08; S, 21.69. Bis[4'-{5,5"-bis(trimethylsilyl)-2,2':3',2"-terthien-5'-ylethynyl}2,2':6',2"-terpyridine-κN1,κN1',κN1"]ruthenium(II) hexafluorophosphate (1). To a solution of ligand 8 (100 mg, 154 μmol) in THF/MeOH (1:2, 15 mL) was added [Ru(DMSO)4(Cl)2] (37.3 mg, 77.1 μmol

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• of isocyanates to ruthenium(II) silylenes [58] (Scheme 8). These complexes do not react with nonpolar substrates (although a possible cycloaddition with azobenzene was reported), and the overall cycloaddition was found to proceed through initial nucleophilic attack at an electrophilic silylene

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• Biology Center, 2121 Simons Drive, West Campus, Lawrence, KS 66047, USA 10.3762/bjoc.8.115 Abstract A series of substituted diaryltriazoles was prepared by a solid-phase-synthesis protocol using a modified Wang resin. The copper(I)- or ruthenium(II)-catalyzed 1,3-cycloaddition on the polymer bead allowed

• and the increased steric demand may explain the decrease in yield in comparison to that of the former series of compounds. The formation of the compound 12o, bearing a particularly bulky substituent, was not observed. Replacing the copper(I) catalyst by a ruthenium(II) complex allows the preparation

• of regioisomers in reaction 3. Instead of the 1,4-disubstituted triazoles obtained from copper(I) catalysis, the complex pentamethylcyclopentadienylbis(triphenylphosphine)ruthenium(II) chloride leads to 1,5-disubstituted triazole compounds [19]. 4-(Azidomethyl)benzoic acid functionalized Wang resin 7

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

• Marc Enßle,
• Stefan Buck,
• Roland Werz and
• Gerhard Maas

Beilstein J. Org. Chem. 2012, 8, 433–440, doi:10.3762/bjoc.8.49

• sulfonium ylide 20 in practically quantitative yield. It has recently been reported that ruthenium(II) porphyrins are suitable catalysts for carbenoid sulfonium ylide formation as well [43]. In continuation of our comparative studies of dirhodium(II,II) tetracarboxylate and tetracarbonyldiruthenium(I,I

Self-assembly of Ru₄ and Ru₈ assemblies by coordination using organometallic Ru(II)₂ precursors: Synthesis, characterization and properties

• Sankarasekaran Shanmugaraju,
• Dipak Samanta and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34

• -sandwich p-cymene ruthenium(II) complexes [Ru2(μ-η4-C2O4)(MeOH)2(η6-p-cymene)2](O3SCF3)2 (1a) or [Ru2(μ-η4-N,N'-diphenyloxamidato)(MeOH)2(η6-p-cymene)2](O3SCF3)2 (1b) separately with an imidazole-based tetratopic donor L in methanol affords two tetranuclear metallamacrocycles 2a and 2b, respectively

• tetranuclear rectangular geometry with the dimensions of 5.53 Å × 12.39 Å. Furthermore, the photo- and electrochemical properties of these newly synthesized assemblies have been studied by using UV–vis absorption and cyclic voltammetry analysis. Keywords: cages; macrocycles; ruthenium(II); self-assembly; self

• allowed the formation of the 3D cage 2c. The use of imidazole-based donor linkers in combination with organometallic half-sandwich ruthenium(II) precursors may generate a wide variety of complex molecular architectures with interesting functional properties. Experimental Materials and methods The acceptor

Synthesis of Ru alkylidene complexes

• Renat Kadyrov and
• Anna Rosiak

Beilstein J. Org. Chem. 2011, 7, 104–110, doi:10.3762/bjoc.7.14

• precursors for the “second generation” catalysts bearing NHC ligands are the alkylidene ruthenium complexes coordinated with two phosphines [1]. For recent reviews see [2][3][4]. There are several routes for accessing five-coordinated ruthenium(II) alkylidene complexes such as diazo-transfer [5] and the

• , J = 7.4 Hz, 1H), 7.21 (dd, J = 8.0 Hz, J = 7.5 Hz, 1H), 7.21 (dt, J = 1.1 Hz, J = 7.4 Hz, 1H), 6.74 (dd, J = 17.5 Hz, J = 10.6 Hz, 1H), 6.71 (s, 1H), 5.41 (d, J = 17.4 Hz, 1H), 7.30 (d, J = 10.6 Hz, 1H), 3.52 (s, 2H) ppm. Dichlorobis(tricyclohexylphosphine)(ethylidene)ruthenium(II) (1a): 1,8

• -Diazabicyclo[5.4.0]undec-7-ene (3.3 mL, 22 mmol) and tricyclohexylphosphine (6.17 g, 22 mmol) were added under an argon atmosphere to a suspension of dichloro(1,5-cyclooctadiene)ruthenium(II) (2.8 g, 10 mmol) in isopropanol (100 mL). The resulting mixture was heated at reflux for 2 h. THF (150 mL) was added to

New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

• Etienne Borré,
• Frederic Caijo,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2010, 6, 1159–1166, doi:10.3762/bjoc.6.132

• -dimesitylimidazolidin-2-ylidene)(2-isopropoxy-5-(trifluoromethylsulfonamido)benzylidene)ruthenium(II) chloride (4a): Following the general procedure using the ligand 6a, complex 4a was isolated as a green powder (62 mg, 73%). 1H (400 MHz, CDCl3, δ): 1.13 (d, J = 6.1 Hz, 6H, 2 CH3), 2.34 (s, 18H, 6 CH), 4.08 (s, 4H, 2

• )benzylidene)ruthenium(II) chloride (4b): Following the general procedure using the ligand 6b, complex 4b was isolated as a green powder (55 mg, 71%). 1H NMR (400 MHz, CDCl3, δ): 1.21 (d, J = 6.1 Hz, 6H, 2 CH3), 2.42 (s, 18H, 6 CH), 4.19 (s, 4H, 2CH2), 4.84 (sept, J = 6.1 Hz, 1H, CH), 6.57 (d, J = 7.3 Hz, 1H

• , CH), 6.71 (bs, 1H, NH), 6.95 (d, J = 7.1 Hz, 1H, CH), 7.08 (s, 4H, 4 CH), 7.33 (s, 1H, CH), 7.91 (d, J = 7.1 Hz, 2H, 2 CH), 8.27 (d, J = 7.3 Hz, 2H, 2 CH), 16.34 (s, 1H, CH). (1,3-dimesitylimidazolidin-2-ylidene)(2-isopropoxy-5-(2-nitrophenylsulfonamido)benzylidene)ruthenium(II) chloride (4c

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• initiators available, we focused this study on the application of the less investigated indenylidene Ru-based catalysts: (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene) dichloro-(3-phenyl-1H-inden-1-ylidene)(tricyclohexylphosphine) ruthenium(II) (C1), (1,3-bis(2,4,6-trimethylphenyl)-2

• -imidazolidinylidene)dichloro-(3-phenyl-1H-inden-1-ylidene)(pyridyl) ruthenium(II) (C2) and the newly developed “boomerang” complex (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(2-(1-methylacetoxy)phenyl)methylene ruthenium(II) (C3) [31] (Figure 2). These indenylidene Ru-complexes provide an

• -trimethylphenyl)-2-imidazolidinylidene) dichloro-(3-phenyl-1H-inden-1-ylidene)(tricyclohexylphosphine) ruthenium(II) (Umicore, C1), (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro-(3-phenyl-1H-inden-1-ylidene) (pyridyl) ruthenium(II) (Umicore, C2), (1,3-bis(2,4,6-trimethylphenyl)-2

A perfluorocyclopentene based diarylethene bearing two terpyridine moieties – synthesis, photochemical properties and influence of transition metal ions

• Falk Wehmeier and
• Jochen Mattay

Beilstein J. Org. Chem. 2010, 6, No. 53, doi:10.3762/bjoc.6.53

• absorption spectra of 10a (solid line), 10aC (dashed line, formed by irradiation with λ = 350 nm) and after re-opening with vis light (dotted line). Influence of transition metals A binuclear Ru(II)-complex For investigations of the photochemical behavior of 10a in the coordination sphere of ruthenium(II

• influences the MLCT transition. This supposition is supported by the difference spectra (Figure 3, the absorption of the free ligand 10aC is shown in grey for comparison). According to studies with similar ruthenium(II) complexes of terpyridine functionalized dithienylethenes [10], the intensity of the MLCT

• other hand, had no influence on the photochromism of the central diarylethene unit. A rather special case is the binuclear ruthenium(II) complex 12: The diarylethene seems to undergo the expected photochromic reaction, but at the same time the absorption intensity of the MLCT band of the complex

Chemoselective reduction of aldehydes by ruthenium trichloride and resin- bound formates

• Basudeb Basu,
• Bablee Mandal,
• Sajal Das,
• Pralay Das and
• Ashis K. Nanda

Beilstein J. Org. Chem. 2008, 4, No. 53, doi:10.3762/bjoc.4.53

• ·3H2O), we carried out the CTH using a well-defined Ru(II) complex [Dichloro(p-cymene)ruthenium(II)] dimer; (2 mol%) under similar conditions and indeed a comparable result was observed (Table 1, entry 11). On the basis of this comparison, it may be presumed that the Ru(III) salt might undergo in situ

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• deprotected product (−)-93. Finally, the introduction of the butenolide segment using a ruthenium(II)-catalyzed Alder-ene reaction followed by selectively reduction furnished cis-solamin (71a). Spectroscopic data for this compound were identical to those reported for cis-solamin isolated from natural sources

Large- scale ruthenium- and enzyme- catalyzed dynamic kinetic resolution of (rac)-1-phenylethanol

• Krisztián Bogár,
• Belén Martín-Matute and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2007, 3, No. 50, doi:10.1186/1860-5397-3-50

• "in situ" racemization of the substrate using a ruthenium(II) racemization catalyst (1) at ambient temperature (Figure 1).[32][34] Many 1-arylethanols are used as intermediates for the synthesis of pharmaceuticals and agrochemicals,[40][41] and they are therefore needed in enantiomerically pure form