Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• conjugate alkynylation and consecutive aldol addition (Scheme 49) [91]. The chiral ruthenium complex C2 (Phebox-type)-catalyzed procedure delivered β-hydroxyketone derivatives 192 having α-propargyl groups in good yields, however, only with low diastereoselectivities (up to 3:1). While the syn-diastereomers

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• state, followed by coordination to the alkyne generates intermediate 109. Migratory insertion of the alkyne results in the ruthenacycle 110. Subsequent reductive elimination generates putative allyl vinyl ether 111 and regenerates the active ruthenium complex. The allyl vinyl ether intermediate

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• purifications can be an easier and more effective alternative. An efficient method to homogeneously scavenge a ruthenium complex used in a metathesis reaction was described by Grela and co-workers on a 60 g scale [89]. The use of heterogeneous scavenger columns in flow mode is sometimes criticized. If the final

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• -carbon precursor for the synthesis. The forward synthesis transformed 2-acetylfuran (20) to its corresponding alcohol 21 through an asymmetric transfer hydrogenation catalyzed by a ruthenium complex (0.5 mol %) in 98% yield with 95% ee (Scheme 2). The azeotropic mixture of HCO2H/Et3N 5:2 was employed as

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• DIPEA reduced the yield substantially (Table 1, entries 21–23). Separate control experiments without catalyst (Table 1, entry 24) or in the dark (Table 1, entry 25) gave no or little conversion to the product, indicating the catalytic role of the ruthenium complex. With the optimized reaction conditions

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• authors precluded a possible photocatalytic process (path II). And indeed, even though from a comparison of the redox potential of [Cu(I)(dap)2]Cl and [Ru(bpy)3]Cl2, the latter should have been capable to promote the photocatalytic reaction, the ruthenium complex was unsuccessful. Hence, to explain the

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• ), which also shed no light on whether this was the open or closed form of the ruthenium complex. Nevertheless, we were confident that the ruthenacycle had been formed, but only in a very small amount. We therefore considered that the ruthenacycle formation might be severely retarded by steric encumbrance

• did suggest that the reaction had worked, albeit in a very low yield. The major mass spectrum peak might be interpreted as successful formation of the ruthenacycle, but we believe that this is not the case and that the ruthenium complex shown in Figure 4 is the more likely interpretation. What was

• Ullmann-coupling to give monoazide 7. Synthesis of monoazidocalix[4]arene 7 under optimized conditions. Synthesis of the putative calix[4]arene mesoionic carbene ruthenium complex 13. Optimization results for the mononitration of calix[4]arene 9. Supporting Information Supporting Information File 392

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• that NHCs groups, in particular, 1,3-bis(2,4,6-trimethylphenyl)imidazolidine are superior in terms of price/quality ratio. We suppose that further advances should be rather aimed at the lower part of the ruthenium complex [15][16][17]. This trend is confirmed partly by the Grubbs catalysts with a

• . Ruthenium complex 11b was efficient in the 0.01 mol % concentration under argon atmosphere and in the 0.1 mol % concentration in air. In case of allylbenzene (14), the action of catalyst 11b (0.1 mol %) gave the mixture of isomeric 1,4-diphenylbutenes 15 and 16 in the ratio of 64:36 in 93% yield. Only a

Synthesis of the aglycon of scorzodihydrostilbenes B and D

• Katja Weimann and
• Manfred Braun

Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56

• . Here, a modified version based upon an in situ generation of the ruthenium complex described by Genet and Darses [16] was applied. Thus, O-protected 2,5-dihydroxyacetophenones 6 were submitted to a hydroarylation reaction with two equivalents of styrenes 7 in the presence of [Ru(p-cymene)Cl2]2 and P(4

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• loading of 0.125 mol %. In 2008, Blechert and Buchmeiser et al. introduced a ruthenium complex featuring an unsymmetrical, chiral NHC ligand 44 and its pyridine derivative 45 (Figure 12) [26]. Both complexes revealed as efficient systems to promote the alternating copolymerization of norbornene (NBE, 46

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• probably the most studied Ru-based photoredox catalyst (abbreviation for ruthenium tris(2,2'-bipyridyl) dichloride; depicted in Scheme 2). The photochemical properties of this complex, commercially available, are gathered in Table 2. By irradiation of the ruthenium complex, there is a formation of a

A tutorial review of stereoretentive olefin metathesis based on ruthenium dithiolate catalysts

• Daniel S. Müller,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2018, 14, 2999–3010, doi:10.3762/bjoc.14.279

• . Therefore, trisubstituted alkenes work best with the same catalysts used for E-alkenes (e.g., Ru-7, Ru-8 and Ru-9). 3 Kinetic studies Grubbs studied the kinetic behavior of several Ru-dithiolate catalysts [6][14][15]. In a typical study the disappearance of the benzylidene proton of the ruthenium complex

• which leads to the formation of methylidene-ruthenium species Ru-A (Scheme 4). Once complex Ru-A is formed, it is prone to be attacked by the electron-rich sulfide ligand positioned opposite to the NHC ligand (trans-influence). This 1,2-sulfide shift generates a new ruthenium complex Ru-B which is

• probably catalytically inactive. This assumption is supported by the isolation of ruthenium complex Ru-13 which was formed by nucleophilic attack of a sulfide ligand onto the electron-poor benzylidene ligand [4]. Hoveyda reasoned that replacing the thiocatecholate ligand (Ru-2) by an electron-deficient

Graphitic carbon nitride prepared from urea as a photocatalyst for visible-light carbon dioxide reduction with the aid of a mononuclear ruthenium(II) complex

• Kazuhiko Maeda,
• Daehyeon An,
• Ryo Kuriki,
• Daling Lu and
• Osamu Ishitani

Beilstein J. Org. Chem. 2018, 14, 1806–1812, doi:10.3762/bjoc.14.153

• filtrates were collected and concentrated to a volume of 30 mL. The amount of the ruthenium complex absorbed was calculated based on the UV–vis spectrum of the filtrate, using Equation 1: where Abefore and Aafter are the absorbance of the solution before and after the adsorption procedure, respectively, and

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• photophysical and photochemical characterizations of this Ru(II)–calixarene conjugate as well as the study of its photoreactivity in the presence of guanosine monophosphate have been achieved. The results show that the ruthenium complex should be able to perform efficiently its photoinduced cytotoxic activity

• , once incorporated into targeted cancer cells thanks to the multivalent platform. Keywords: anticancer drug; calixarene; cell targeting; RGD peptide; ruthenium complex; Introduction Long-living luminescent polyazaaromatic ruthenium(II) complexes are intensively studied in a biological context, in

• presented in Figure 2, as issued from a molecular dynamics (MD) simulations. The ruthenium complex and the RGD units are spatially well-separated thanks to their grafting on opposite faces of the rigid calixarene-based platform. In this conformation, the distances between the Ru atom and each of the nearest

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• -sulfonyl amides failed to react. Interestingly, Zhang and co-workers demonstrated that this reaction could be performed as well using bismuth oxybromide (BiOBr) nanosheets instead of a ruthenium complex as the photocatalyst (Scheme 5) [12]. The reaction unfortunately suffered from the same limitations

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• using a mediator, rhenium bipyridine (a molecule similar to the ruthenium complex in Figure 2B). A concomitant development (complexity increase) of membranes and light/energy harvesting/conversion systems can thus be seen as a prerequisite in the evolution of the ancestral bioenergetics en route to the

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• hydroxy group has a great impact on the biological activities of 5-hydroxyflavonids [83]. Starting from [RuCl2(p-cymene)]2, Ag2CO3 and CF3COOH, they prepared a ruthenium complex, which could achieve the regioselective hydroxylation of flavones at 80 °C in TFA/TFAA in the presence of PhI(TFA)2 as oxidant

• and carbamates. [RuCl2(p-cymene)]2 catalyzed hydroxylation of benzaldehydes. [RuCl2(p-cymene)]2 catalyzed hydroxylation of ethyl benzoates, benzamides and carbamates. Different regioselective ortho-hydroxylation. Ruthenium-complex-catalyzed hydroxylation of flavones. Vanadium-catalyzed hydroxylation

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

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

• 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

Creating molecular macrocycles for anion recognition

• Amar H. Flood

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

Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

• Krzysztof Skowerski,
• Jacek Białecki,
• Stefan J. Czarnocki,
• Karolina Żukowska and
• Karol Grela

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

• literature that ruthenium residues, present in the reaction mixture after olefin metathesis, can serve as an in situ homogeneous catalyst for high pressure hydrogenation of the newly formed C–C double bonds [57][58][59][60][61]. On this basis, we assumed that the ruthenium complex impregnated on carbon 8-C

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• (Table 4, entry 4) [32]. The low product yield was caused not only by the unselective attack of catalyst on diene substrate but also by competitive SM reactions of both substrates. Interestingly, the new ruthenium complex showed a different regioselectivity compared to catalysts 1 and 2. The metathetic

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• those obtained with GII were obtained. In the presence of a non-bulky primary amine such as n-butylamine, the bis-aminobenzylidene 17 was formed and complete decomposition was noticed after 12 h at rt yielding ruthenium complex 18 and amine 10. In the presence of secondary amines b and c and sp2 amine d

• mechanism involving a deprotonation of the metallacyclobutane intermediate 23 was hypothesized. The resulting anionic ruthenium complex 24 would be protonated and, after elimination, alkene 22 and unidentified ruthenium complexes would be produced (Scheme 10). According to these mechanistic investigations

• , several pathways are involved in the amine-induced catalyst decomposition depending on the nature of the amine and of the ruthenium complex. Non-bulky primary amines can attack directly benzylidene species and are responsible for the fast degradation of the catalyst. In the case of a phosphine-containing

Computational study of productive and non-productive cycles in fluoroalkene metathesis

• Markéta Rybáčková,
• Jan Hošek,
• Ondřej Šimůnek,
• Viola Kolaříková and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

• 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

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

• this increased stability diminished the activity of 21 when compared to 15 [52]. In 2000, Dowden [53] and co-workers reported the use of a polystyrene-supported ruthenium complex 24 (Scheme 5); a variation of the Hoveyda–Grubbs catalyst. It could be reused up to 5 times without loss of activity and