Synthetic approaches to multifunctional indenes

• Neus Mesquida,
• Sara López-Pérez,
• Immaculada Dinarès and
• Ermitas Alcalde

Beilstein J. Org. Chem. 2011, 7, 1739–1744, doi:10.3762/bjoc.7.204

• ; amides; indanones; indenes; organometallic reagents; Introduction Compounds with an indene core are of great interest as precursors of metallocene complexes for catalytic polymerization processes, as well as being present in N-heterocyclic carbene ligands and functional materials [1][2][3][4][5][6][7][8

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• Pd-catalyzed cross-coupling approach starting from 1-chloro-2-iodobenzenes, phenylacetylene and a variety of primary amines [28][29]. The sequential three-component reaction was performed with the aid of an N-heterocyclic carbene-palladium complex generated in situ, derived from imidazolium salt 50

Combination of gold catalysis and Selectfluor for the synthesis of fluorinated nitrogen heterocycles

• Antoine Simonneau,
• Pierre Garcia,
• Jean-Philippe Goddard,
• Virginie Mouriès-Mansuy,
• Max Malacria and
• Louis Fensterbank

Beilstein J. Org. Chem. 2011, 7, 1379–1386, doi:10.3762/bjoc.7.162

• hydrofluorination of alkynes catalyzed by N-heterocyclic carbene gold(I) complexes [4], or by fluorodeauration of transient vinyl gold species [5][6], has been previously reported in the literature. On the basis of our recent results on the gold-catalyzed cyclization of enynes [7][8][9][10] and allenylhydrazones

Gold(I)-catalyzed synthesis of γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with alcohols

• Michel Chiarucci,
• Mirko Locritani,
• Gianpiero Cera and
• Marco Bandini

Beilstein J. Org. Chem. 2011, 7, 1198–1204, doi:10.3762/bjoc.7.139

• Michel Chiarucci Mirko Locritani Gianpiero Cera Marco Bandini Dipartimento di Chimica “G. Ciamician”, Alma Mater Studiorum – Università di Bologna, Via Selmi 2, 40126 Bologna, Italy 10.3762/bjoc.7.139 Abstract Gold(I)-N-heterocyclic carbene (NHC) complexes proved to be a reliable catalytic system

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• regenerating the catalyst (PtCl2). In addition, DFT calculations suggested that gold catalysts could be even more active than PtCl2. Accordingly, the use of a cationic Au(I) catalyst containing a σ-donating N-heterocyclic carbene ligand (Au6/AgSbF6, Scheme 26) enabled these reactions at lower temperatures and

Triazole–Au(I) complex as chemoselective catalyst in promoting propargyl ester rearrangements

• Dawei Wang,
• Yanwei Zhang,
• Rong Cai and
• Xiaodong Shi

Beilstein J. Org. Chem. 2011, 7, 1014–1020, doi:10.3762/bjoc.7.115

• (I) catalysis. The recent development of N-heterocyclic carbene (NHC) derivatives has significantly expanded the choice of ligands by improving the catalyst stability through metal-ligand backbonding [17][18][19][20]. To access the active catalyst [L–Au]+, stable precursors L–Au–X or [L–Au–X]+·A

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• % PPh3AuCl/5 mol % AgOTf in dichloroethane at 80 °C gave alkylidenecyclobutanamine 160 in 65% yield as a single olefin isomer (Scheme 28). The formation of tri- and tetrasubstituted pyrroles 163 [74] via cationic N-heterocyclic carbene–gold(I) complex catalyzed amino Claisen rearrangement of N-propargyl-β

The role of silver additives in gold-mediated C–H functionalisation

• Scott R. Patrick,
• Ine I. F. Boogaerts,
• Sylvain Gaillard,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2011, 7, 892–896, doi:10.3762/bjoc.7.102

• functionalisation of aromatic C–H bonds. Doubt is cast on the commonly cited route of halide abstraction from gold and evidence of substrate activation is given. Keywords: C–H functionalisation; gold catalyst; halide abstraction; N-heterocyclic carbene; silver salt; substrate activation; Introduction The use of

Solvent- and ligand-induced switch of selectivity in gold(I)-catalyzed tandem reactions of 3-propargylindoles

• Estela Álvarez,
• Delia Miguel,
• Patricia García-García,
• Manuel A. Fernández-Rodríguez,
• Félix Rodríguez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 786–793, doi:10.3762/bjoc.7.89

• N-heterocyclic carbene ligands [30] also produced 3a as the major compound of the corresponding mixtures (Table 1, entries 5 and 6). It was decided to increase the π-acceptor character of the ligand [31], and, in this case, the employment of a triphenylphosphite–gold(I) complex led to a slight

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• moderate results, whereas the highest yield and diastereoselectivity was obtained when the strong σ donor and weak π acceptor N-heterocyclic carbene IPr was the ligand. The latter was indeed anticipated to give an organogold with a higher carbene-like reactivity which favors olefin cyclopropanation. AuCl

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• showed good catalytic activities in the asymmetric intramolecular hydroamination reaction to give the corresponding product in moderate ee. Keywords: chiral mono(N-heterocyclic carbene) complex; Heck–Mizoroki reaction; hydroamination; Suzuki–Miyaura reaction; Introduction N-heterocyclic carbene (NHC

• –Au(I) complex (S)-6a with thermal ellipsoids at the 30% probability level. Selected bond distances (Å) and angles (deg): Au1–C1 = 2.036(14), Au1–I1 = 2.5093(13), C1–Au1–I1 = 176.5(3), N1–C1–Au1 = 125.7(9), N2–C1–Au = 126.1(9). Synthesis of N-heterocyclic carbene precursor. Synthesis of mono(NHC)–Pd

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• intermolecular ene–yne metathesis versions [33][34][35][36][37][38]. For EYCM the two pathways involve either an alkyne interaction with a methylidene metal species (Scheme 3) or an alkylidene metal intermediate (Scheme 4). In both cases, the ancillary ligands tricyclohexylphosphine or N-heterocyclic carbene

Olefin metathesis in nano-sized systems

• Didier Astruc,
• Abdou K. Diallo,
• Sylvain Gatard,
• Liyuan Liang,
• Cátia Ornelas,
• Victor Martinez,
• Denise Méry and
• Jaime Ruiz

Beilstein J. Org. Chem. 2011, 7, 94–103, doi:10.3762/bjoc.7.13

• an intermediate tetracyclic iron arene complex. Furthermore and interestingly, when the metathesis reaction was carried out in refluxing dichloroethane with the addition of the second-generation Grubbs catalyst [RuCl2(=CHPh)(bis-N-mesityl-NHC)], 7, (Scheme 3, NHC = N-heterocyclic carbene), the di

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• ]. Industrial scale-up of these methods has already been applied on the 100 kg scale for arylpiperazines and different diarylamines [21]. In addition, Nolan et al. and Organ et al. have reported Pd-N-heterocyclic carbene (NHC)-catalysed Buchwald–Hartwig amination protocols that provide access to a range of

The intriguing modeling of cis–trans selectivity in ruthenium-catalyzed olefin metathesis

• Naeimeh Bahri-Laleh,
• Raffaele Credendino and
• Luigi Cavallo

Beilstein J. Org. Chem. 2011, 7, 40–45, doi:10.3762/bjoc.7.7

• SIMes N-heterocyclic carbene ligand, see Scheme 2. Although it is well known that the steric hindrance of the olefin substituent has a remarkable role on both reactivity and products distribution, propene can still be considered as a prototype of terminal olefins, and can provide insights into 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

• ) starting from renewable resources and quite inexpensive base chemicals. Results: This cross-metathesis reaction was carried out with several phosphine and N-heterocyclic carbene ruthenium catalysts. The reaction conditions were optimised for high conversions in combination with high cross-metathesis

• conversions in combination with high cross-metathesis selectivities. Additionally, several phosphine and N-heterocyclic carbene ruthenium catalysts were studied. The optimised reaction conditions were subsequently investigated in the cross-metathesis reaction of oleic acid (7) with the unprotected cis-2

• bearing N-heterocyclic carbene ligands (Table 1, entries 2 and 4–8) [29]. Up to 48% of methyl oleate (1) was converted and the yields of the cross-metathesis products 3 and 4 of ca. 28% were achievable with ruthenium catalysts [Ru]-2 and [Ru]-4 (Table 1, entries 2 and 4). Here, the self-metathesis

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

• been facilitated [2][3][4]. However, many research groups have focused their research on the development of more efficient precatalysts (Figure 1). In 1999, Grubbs (1a) [5] and Nolan (1b) [6] reported ruthenium species bearing one N-heterocyclic carbene (NHC) moiety. Despite the stability enhancement

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

• parameters. Keywords: N-heterocyclic carbene; olefin metathesis; percent buried volume; ruthenium–indenylidene; Tolman electronic parameter; Introduction The use of N-heterocyclic carbenes (NHC) as spectator ligands in ruthenium-mediated olefin metathesis represents one of the most important breakthroughs

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

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

• respective yields and the required reaction times. In line with the development of ruthenium benzylidene initiators [66][67], the phosphane ligand was replaced by an N-heterocyclic carbene (NHCs) in the photoactivated precatalysts. Accordingly, Noels et al. [68][69] synthesised a range of NHC substituted

Halide exchanged Hoveyda-type complexes in olefin metathesis

• Julia Wappel,
• César A. Urbina-Blanco,
• Mudassar Abbas,
• Jörg H. Albering,
• Robert Saf,
• Steven P. Nolan and
• Christian Slugovc

Beilstein J. Org. Chem. 2010, 6, 1091–1098, doi:10.3762/bjoc.6.125

• 16.10 ppm. All other features of the 1H NMR spectrum of 2 are similar to those of 1 indicating slightly hindered rotation of the N-heterocyclic carbene ligand and a trans-disposition of the two halide ligands. In contrast, the rotation of the NHC ligand around the Ru–NHC bond in 3 is hindered as shown

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• . Various aryltriazenes were investigated as electrophilic substrates at room temperature to give biaryls in good to excellent yields and showed good chemoselectivity over aryl halides in the reactions. Keywords: 1-aryltriazenes; N-heterocyclic carbene–palladium complex; polymer-supported catalyst

• general study on the Suzuki–Miyaura reactions of 1-aryltriazenes under heterogeneous catalysis described to date. Previously, we reported an active and recyclable polystyrene-supported Pd–NHC (N-heterocyclic carbene) catalyst 1 (Scheme 1) for the Suzuki–Miyaura cross-coupling reactions of aryl bromides

The C–F bond as a conformational tool in organic and biological chemistry

• Luke Hunter

Beilstein J. Org. Chem. 2010, 6, No. 38, doi:10.3762/bjoc.6.38

• , Figure 10), with the key transannular aldol reaction (44→45) proceeding in high yield and with impressive enantioselectivity [35]. Fluorine-substituted organocatalysts are also useful in the asymmetric Stetter reaction (Figure 11) [36]. N-Heterocyclic carbene 49 was identified as a promising first

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• *-catalyst 33 (Scheme 14). This N-heterocyclic carbene Ir-complex is capable of catalyzing FC alkylations not only with benzyl alcohols and styrenes but also utilizing aldehydes and acetophenones 32, which are reduced prior to the FC-type alkylation in the same reaction vessel (Scheme 14). Here isopropanol

Expedient syntheses of the N-heterocyclic carbene precursor imidazolium salts IPr·HCl, IMes·HCl and IXy·HCl

• Lukas Hintermann

Beilstein J. Org. Chem. 2007, 3, No. 22, doi:10.1186/1860-5397-3-22

• -dimethylphenyl), precursors to widely used N-heterocyclic carbene (NHC) ligands and catalysts, were prepared in high yields (81%, 69% and 89%, respectively) by the reaction of 1,4-diaryl-1, 4-diazabutadienes, paraformaldehyde and chlorotrimethylsilane in dilute ethyl acetate solution. A reaction mechanism