Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• heteroleptic complexes, bearing one N-heterocyclic carbene (NHC) (16–19, Figure 1) and one phosphine as ligands, represented the second crucial turning point in this chemistry. Following Herrmann’s report on bis-NHC ruthenium complexes (10–15) and their low activity [39], independently and simultaneously the

• 2009, surely inspired by the aforementioned work, the Verpoort group reported a family of indenylidene Schiff base–ruthenium complexes (111a–f, Figure 17) for CM and RCM reactions in air [98]. They combined the higher thermal stability of indenylidene complexes and the tunability and stability of

• limits even further. As seen in this review, conducting metathesis-type reactions in air, in the presence of water and under high temperature has become more concrete, with several groups leading the charge [62][86]. NHC-Ruthenium complexes and widely used NHC carbenes. Scope of RCM reactions with

Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• , China 10.3762/bjoc.11.194 Abstract Ruthenium complexes [Ru(L1)2(CH3CN)2](PF6)2 (1), [RuL1(CH3CN)4](PF6)2 (2) and [RuL2(CH3CN)3](PF6)2 (3) (L1= 3-methyl-1-(pyrimidine-2-yl)imidazolylidene, L2 = 1,3-bis(pyridin-2-ylmethyl)benzimidazolylidene) were obtained through a transmetallation reaction of the

• molecular structures of the complexes 4 and 5 were also studied by X-ray diffraction analysis. These ruthenium complexes have proven to be efficient catalysts for transfer hydrogenation of various ketones. Keywords: N-heterocyclic carbene; ruthenium; transfer hydrogenation; Introduction N-Heterocyclic

• [8][9][10][11][12][13][14][15][16] have been reported. In the family of metal complexes supported by functionalized NHCs, ruthenium complexes have long been a research focus on various applications such as catalysis and photochemistry [17][18][19][20][21][22][23][24][25][26]. However, the majority of

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

• Thibault E. Schmid,
• Florian Modicom,
• Adrien Dumas,
• Etienne Borré,
• Loic Toupet,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

• of cocatalyst. While first examples of latent catalysts were based on phosphine-containing ruthenium complexes bearing a Schiff base ligand (O–N) [9] replacement of the phosphine ligand by sterically demanding and strongly σ-donor N-heterocyclic carbenes (NHC) afforded catalysts with improved

• in model ring closing metathesis and cross-metathesis transformations. Results and Discussion With the objective to develop an attractive strategy for the synthesis of indenylidene-picolinic ruthenium complexes, we initially attempted their preparation using a silver-free methodology. In fact, silver

• . Synthesis of complex 4a and 4b from (SIPr)(pyridine)RuCl2(indenylidene) (5). Substrate scope in RCM, CM and enyne metathesis catalyzed by 4aa. Supporting Information Supporting Information File 38: Full experimental procedures and detailed analytical data for ruthenium complexes. Acknowledgements This

Ruthenium indenylidene “1^st generation” olefin metathesis catalysts containing triisopropyl phosphite

• Stefano Guidone,
• Fady Nahra,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2015, 11, 1520–1527, doi:10.3762/bjoc.11.166

• ruthenium complexes used in olefin metathesis reactions. Molecular structure of mixed phosphine/phosphite complex 1. Hydrogen atoms are omitted for clarity. Molecular structure of 2 and the ylide 3. Hydrogen atoms and solvent molecules are omitted for clarity. Selected bond distances (Å) and angles (°) (ESD

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

• Piotr Roszkowski,
• Jan. K. Maurin and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2015, 11, 1509–1513, doi:10.3762/bjoc.11.164

• : chiral diamines; enantioselective reduction; epinastine; mianserin; ruthenium complexes; Introduction Mianserin (1) is a tetracyclic compound widely used as a drug in the treatment of depression. Despite the fact that the (S)-(+)-enantiomer of mianserin is more potent than the (R)-antipode in

Consequences of the electronic tuning of latent ruthenium-based olefin metathesis catalysts on their reactivity

• Karolina Żukowska,
• Eva Pump,
• Aleksandra E. Pazio,
• Krzysztof Woźniak,
• Luigi Cavallo and
• Christian Slugovc

Beilstein J. Org. Chem. 2015, 11, 1458–1468, doi:10.3762/bjoc.11.158

• their user-friendly character caused by a wide functional group-tolerance and high oxygen and moisture stability. Although a great progress has been made, the unsuitability of ruthenium complexes for high temperature applications remains one of the greatest challenges in the field. Modifications in the

• . Big symbols: thermogravimetric analysis (TGA); no symbols: differential scanning calorimetry (DSC). trans–cis Isomerization. Synthesis of the ligand precursors. Synthesis of the ruthenium complexes. Possible reaction pathways of 16. Supporting Information Supporting Information File 360: Full

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• [11][12] have shown how rotamers can indeed influence the electronic coupling in bis-ruthenium complexes separated by oligoynediyl spacers. In addition, an increased interaction between redox centres upon linking them together in cyclic structures was previously observed in ferrocene-dimers [13]. Here

Morita–Baylis–Hillman reaction of acrylamide with isatin derivatives

• Radhey M. Singh,
• Kishor Chandra Bharadwaj and
• Dharmendra Kumar Tiwari

Beilstein J. Org. Chem. 2014, 10, 2975–2980, doi:10.3762/bjoc.10.315

• appending other functionalities/groups for intramolecular transformations. Other reports have used this feature for the development of an intramolecular MBH reaction: Corey et al. (total synthesis) [29], Pigge et al. (ruthenium complexes as an electrophile) [30], and Basavaiah et al. [31][32]. Isatin has

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

• . Ow stands for water molecules. Ruthenium complexes 7 and 8 in Newman projection along the Ru–P bond. Titration of HUGPHOS-1 with [Rh(CO)2Cl]2 at 25 °C. High pressure NMR spectra of 13 under CO/H2 (1:1) recorded in toluene-d8 (at various temperatures and pressures), showing its conversion into trans

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

• -coupling of benzyl or alkyl halides with racemic secondary phosphines have been developed. These reactions were catalyzed by chiral platinum or ruthenium complexes. The enantioselectivity is based on a dynamic kinetic resolution. Upon reaction with the catalyst precursor containing a chiral ligand (L*), a

• suggested that the alkynyl hydrogen acts as the hydrogen source for the hydrophosphination. This can also explain why the method was not applicable to internal alkynes. Silanes have also been added as the source for hydrogen [241]. Ruthenium complexes are the first catalysts reported for the direct

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

• , and this can be attributed to the deposition of macrocycles on the electrode surface. Based on the electrochemical activity of other reported ruthenium complexes, the observed cathodic peaks are roughly assigned to one-electron reductions of the bridged quinonato or diphenyloxamidato ligands, and the

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

The cross-metathesis of methyl oleate with cis-2-butene-1,4-diyl diacetate and the influence of protecting groups

• Arno Behr and
• Jessica Pérez Gomes

Beilstein J. Org. Chem. 2011, 7, 1–8, doi:10.3762/bjoc.7.1

• catalytic activity of the ruthenium complexes [Ru]-1 to [Ru]-8 (Figure 1) using a catalyst loading of 1.0 mol % was evaluated in the cross-metathesis of methyl oleate (1) with cis-2-butene-1,4-diyl diacetate (2). The reactions were performed with a fivefold excess of 2 in toluene at 50 °C for 5 h to shift

• catalysts illustrate once more their higher metathesis activity and their higher tolerance towards functional groups [2]. Comparable or higher conversions of 1 and cross-metathesis yields of 3 and 4 (Table 1, entries 5–8) were obtained with ruthenium complexes [Ru]-5–[Ru]-8. Due to their bidentate Schiff

• 4.0 mol % was necessary to produce similar results (Table 6, entry 3). With regard to technical implementation, it seems to be more economical to use the protected substrates, since the catalyst loading of the expensive ruthenium complexes is considerably higher. Conclusion In conclusion, the cross

Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

• César A. Urbina-Blanco,
• Xavier Bantreil,
• Hervé Clavier,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2010, 6, 1120–1126, doi:10.3762/bjoc.6.128

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2010, 6, 1106–1119, doi:10.3762/bjoc.6.127

• UV irradiation. The ruthenium complexes 12 showed much higher reactivity in the polymerisation of norbornene, albeit none of these complexes was completely thermally latent for this reaction. The remarkable tolerance of 12b to impurities and water, was highlighted by the fact that polymerisation can

• . Ruthenium complexes with p-cymene and NHC ligands. Photoactivated cationic ROMP precatalysts. Different monomers for PROMP. Light-induced cationic catalysts for ROMP. Sulfur chelated ruthenium benzylidene pre-catalysts for olefin metathesis. Photoacid generators for photoinduced metathesis. Encapsulated 39

• 41. Activation of ruthenium complexes with and without irradiationa. Effect of light on the ROMP of cyclooctene using 16g as catalyst. Polymerisation results for monomers 24–29 by 22 and 23a. Photo RCM of different substratesa. PROMP with sulfur chelated complexesa. RCM by PAG and precatalysts 36 and

Progress in metathesis chemistry

• Karol Grela

Beilstein J. Org. Chem. 2010, 6, 1089–1090, doi:10.3762/bjoc.6.124

• development of the metathesis method in organic synthesis” has been fully recognized by the award of the Nobel Prize in Chemistry for 2005 jointly to Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock [2]. Organic chemists are now provided with molybdenum and ruthenium complexes that present good

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

• Satoru Arimitsu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

• reaction time. The stereochemistry of 7a and 7b was determined by COSY and NOESY experiments. Recently, various tandem reactions with ruthenium complexes have become popular in organic chemistry because Ru(II) complexes are capable of catalyzing additional reactions [26][27]. Since our enyne metathesis