Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• reaction, is a non-toxic byproduct. However, the poor ability of the hydroxy moiety, as a leaving group, has limited the use of the allyl alcohols as substrates. Correlatively, some efforts have been made in this direction by the use of transition metals such as copper [6], nickel [7], ruthenium (I, II) [8

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• Tetraponera sp. [1][2]. It is also present in ligands of ruthenium-based catalysts for metathesis [3], in imidazolidines acting as antiprotozoal and antibacterial agents [4][5], in Tröger’s base derivatives with diverse applications [6][7][8][9][10][11][12][13][14] (e.g., asymmetric catalysis, supramolecular

Organometallic chemistry

• Bernd F. Straub,
• Rolf Gleiter,
• Claudia Meier and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 2216–2221, doi:10.3762/bjoc.12.213

• mechanism of the Dötz reaction, he found that chromacyclobutene structures were unrealistic intermediates and instead proposed vinylcarbene complexes as much more stable isomers [64][68][88]. Other research projects of his group included the synthesis of ruthenium–carbene complexes with cis-dichloro ligands

Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene with alcohols

• Katrina Tait,
• Oday Alrifai,
• Rebecca Boutin,
• Jamie Haner and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 2189–2196, doi:10.3762/bjoc.12.209

• heteroatomic nucleophiles [23][24], or when ruthenium catalysts are used with alcohol nucleophiles [25]. Furthermore, unsubstituted dihydronaphthalenols 7 can be obtained through the reductive ring opening of oxabicyclic alkene 1 with hydride nucleophiles [26]. These intermediates find synthetic uses in the

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

• firmly established that in addition to the permanganate-mediated reaction, both ruthenium- as well as osmium tetroxide mediate the same transformation (cf. Scheme 3) and that these reactions can, contrary to the original permanganate-promoted process, be run in a catalytic fashion. All published

• functional theory calculations both by Strassner and co-workers (Mn(VII) and Os(VIII)) [12][13] and by Kirchner and co-workers (Ru(VIII)) [14]. Reasonable fractions of the trans-THF isomer can be produced using ruthenium tetroxide in specifically optimized solvent compositions [15] (for other means to obtain

• ][16][17]. In addition, for Ru(VIII) [17][18][19] and Mn(VII) [21] it has been shown that also 1,6-dienes serve as substrates and can thus be directly converted to tetrahydropyrans [20][21][22]; ruthenium tetroxide even oxidizes 1,7-dienes to oxepans [23]. However, it has to be noted that the latter

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• development of an efficient ruthenium catalyst for selective oxidation of both aliphatic and aromatic amines to nitriles [22]. The catalytic effectiveness of this ruthenium terpyridine complex was ascribed to the polarization effect of the azulene moiety attached at the terpyridine unit and it was sustained

• by comparison with analogues ruthenium complexes with unsubstituted or 4′-phenyl-substituted terpyridine. In this contribution we report on the green synthesis and physicochemical investigations of the 4′-azulenyl-substituted terpyridines with particular interest on the fluorescence properties. The

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

Cp₂TiCl/D₂O/Mn, a formidable reagent for the deuteration of organic compounds

• Antonio Rosales and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2016, 12, 1585–1589, doi:10.3762/bjoc.12.154

• C–H bonds [8][9]. More recently, organometallic catalysts have been used in the development of methods for deuteration of organic compounds. In this sense, it has been reported that iridium complexes can catalyse the H/D exchange of arenes, cyclic alkenes and vinyl groups [10][11][12]. Ruthenium

Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O)”s: functionalization, rotational barriers and non-covalent interactions

• Golo Storch,
• Sebastian Pallmann,
• Frank Rominger and
• Oliver Trapp

Beilstein J. Org. Chem. 2016, 12, 1453–1458, doi:10.3762/bjoc.12.141

• Mikami reported the stereochemical alignment of BIPHEP ligands in ruthenium complexes upon addition of chiral diamine co-ligands [1][2]. The resulting complexes were successfully employed in enantioselective ketone hydrogenation. Further examples of such systems are BIPHEP complexes of rhodium [3][4][5

Reactivity studies of pincer bis-protic N-heterocyclic carbene complexes of platinum and palladium under basic conditions

• David C. Marelius,
• Curtis E. Moore,
• Arnold L. Rheingold and
• Douglas B. Grotjahn

Beilstein J. Org. Chem. 2016, 12, 1334–1339, doi:10.3762/bjoc.12.126

• the change from ruthenium to platinum [17]. To see if the faster ligand exchange would lead to LiCl loss with palladium, 7-Pd was synthesized. Unfortunately, similar results were observed with the platinum analog where 1-heptene did not react with 7-Pd (which was then converted to 8-Pd by addition of

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• to create three intermolecular bonds. A ruthenium–porphyrin complex-catalyzed three-component reaction of α-diazophosphonates 180, nitrosoarenes 181, and alkynes 182 to give multifunctionalized aziridinylphosphonates 183 has been reported by Reddy et al. (Scheme 39) [77]. The desired

• conditions. CuI-catalyzed four-component reactions of methyleneaziridines towards alkylphosphonates. Ruthenium–porphyrin complex-catalyzed three-component synthesis of aziridinylphosphonates and its proposed mechanism. Copper(I)-catalyzed three-component reaction towards 1,2,3-triazolyl-5-phosphonates. Three

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• preliminary form [9], fluorescence emission of their azomethine precursors was reported for pyrene-1-carboxaldehyde thiosemicarbazone and Schiff bases as well as their metal complexes [16][17][18][19][20][21]. Such properties were described for, e.g., ruthenium(II) complexes of (5-chloropyridin-2-yl)-(pyren-1

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• as a widely used privileged ligand class [4][5][6][7][8][9][10][11][12]. One of the major areas of application of PHOX and related N,P ligands is the iridium-catalyzed asymmetric hydrogenation [13][14][15][16]. Compared to rhodium and ruthenium catalysts, iridium complexes derived from chiral N,P

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

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

• Sebastian Bretzke,
• Stephan Scheeff,
• Felicitas Vollmeyer,
• Friederike Eberhagen,
• Frank Rominger and
• Dirk Menche

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

• 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

• ] 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

• Jinming Guan,
• Matthew Hachey,
• Lekha Puri,
• Vanessa Howieson,
• Kevin J. Saliba and
• Karine Auclair

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

• J. V. Santiago and
• A. H. L. Machado

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

• 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

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

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

• Julia Wappel,
• Roland C. Fischer,
• Luigi Cavallo,
• Christian Slugovc and
• Albert Poater

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

• 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

• 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

• 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

• 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

• 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

• 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

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

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