Self-assembly of metallosupramolecular rhombi from chiral concave 9,9’-spirobifluorene-derived bis(pyridine) ligands

• Rainer Hovorka,
• Sophie Hytteballe,
• Torsten Piehler,
• Georg Meyer-Eppler,
• Filip Topić,
• Kari Rissanen,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 432–441, doi:10.3762/bjoc.10.40

• compared to the ratios obtained by other techniques, e.g. NMR spectroscopy, as we have recently reported [28]. Finally, we were able to grow single crystals of the dinuclear palladium complexes derived from the racemic ligands from a 3:1 mixture of dichloromethane and acetonitrile using ethyl acetate as

Palladium(II)-catalyzed Heck reaction of aryl halides and arylboronic acids with olefins under mild conditions

• Tanveer Mahamadali Shaikh and
• Fung-E Hong

Beilstein J. Org. Chem. 2013, 9, 1578–1588, doi:10.3762/bjoc.9.180

• substrates [12][13][14][15][16]. The class of phosphine-ligated palladium complexes [17][18][19][20][21] represents the most frequently employed precatalysts to achieve high reactivities and selectivities for such reactions. However, such trisubstituted phosphines in the palladium complexes are often air

• compared to the conventional trisubstituted phosphine ligands. Despite this advantage, the potential of these ligands has not been fully realized in Heck arylation reactions. Up to now, only a few examples of utilizing SPO-ligated palladium complexes in oxidative Heck reactions have been demonstrated [28

• . Therefore, the development of an alternative general and mild procedure employing a stable and inexpensive ligand is still in great demand. Furthermore, the application of palladium complexes in the oxidative coupling of organo-boron compounds with olefins has attracted much attention in recent years [33

Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• are used. Characterization of these palladium complexes strongly supports a mechanistic proposal for the catalytic guanylation of anilines using PdCl2(NCCH3)2 as catalyst that involves the intermediacy of these Pd(II) complexes. Keywords: coordination chemistry; guanylation reaction; homogeneous

• catalysis; palladium complexes; reactive intermediates; Introduction N-Arylguanidines are important compounds with interesting biological activities [1][2] such as fungicides [3] and also in supramolecular chemistry as complementary partners of carboxylate and nitro groups [4][5][6][7]. Some of these

• the present report we describe the study of palladium-catalyzed guanylation of three additional anilines (1a–c) with N,N’-diisopropylcarbodiimide (2). For these reactions we have been able to characterize three palladium complexes of the type of bis(anilino)Pd(II) (3a–c) as well as three palladium

N-Heterocyclic carbene–palladium catalysts for the direct arylation of pyrrole derivatives with aryl chlorides

• Ismail Özdemir,
• Nevin Gürbüz,
• Nazan Kaloğlu,
• Öznur Doğan,
• Murat Kaloğlu,
• Christian Bruneau and
• Henri Doucet

Beilstein J. Org. Chem. 2013, 9, 303–312, doi:10.3762/bjoc.9.35

• coupling partners. The desired coupling products were obtained in moderate to good yields by using 1 mol % of these air-stable palladium complexes. This is an advantage compared to the procedures employing air-sensitive phosphines, which have been previously shown to promote the coupling of aryl chlorides

• . Palladium complexes exhibit a characteristic ν(NCN) band typically at 1407–1477 cm−1. The formation of the Pd–NHC complexes was confirmed by the absence of the 1H NMR resonance signal of the acidic benzimidazolium C2–H. The 13C NMR spectra of Pd–NHC complexes exhibit a resonance signal in the 181.2–183.6

Alkyne hydroarylation with Au N-heterocyclic carbene catalysts

• Cristina Tubaro,
• Marco Baron,
• Andrea Biffis and
• Marino Basato

Beilstein J. Org. Chem. 2013, 9, 246–253, doi:10.3762/bjoc.9.29

• (II) salts as catalyst [8][9][10]. Palladium complexes with N-heterocyclic carbene (NHC) ligands have since been showcased as highly efficient catalysts for this reaction [11][12][13][14]. Alternative catalytic systems based on salts or complexes of other noble metals, such as platinum [15][16][17

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• thought to explain the outcome of the reaction. Firstly, Pd(II) catalyst promotes the formation of the π-allyl-palladium complex VIII, which can evolve by coordination of the N-1 or C-3 positions of the indole nucleus giving the palladium complexes IX and X, respectively. The latter quickly converts into

• -alkyl-palladium complexes, favoring a transient palladium oxidation or the generation of hetero-bimetallic palladium/copper intermediates, which may undergo nucleophilic attack by the solvent on the exocyclic carbon to give the iminium intermediates XIX (Scheme 28). Finally, the latter may be converted

• -olefin complexes XXII by aminopalladation leading to the intermediates XXIII, are involved as independent steps in the mechanism of the reaction. The final compounds 52 arise from the halide migration on the σ-alkyl-palladium complexes XXIV, stabilized by the presence of CuX2 in the medium of the

Palladium-catalyzed substitution of (coumarinyl)methyl acetates with C-, N-, and S-nucleophiles

• Kalicharan Chattopadhyay,
• Erik Fenster,
• Alexander J. Grenning and
• Jon A. Tunge

Beilstein J. Org. Chem. 2012, 8, 1200–1207, doi:10.3762/bjoc.8.133

• the enolate proceeds in highest yield in acetonitrile (2a, Table 1, entry 3). Bidentate ligated palladium complexes gave mixed results: the Pd/dppf complex (Table 1,entry 4) catalyzed the reaction smoothly, while little product was seen on using the Pd/BINAP complex (Table 1,entry 5). Under the best

Synthesis of axially chiral oxazoline–carbene ligands with an N-naphthyl framework and a study of their coordination with AuCl·SMe₂

• Feijun Wang,
• Shengke Li,
• Mingliang Qu,
• Mei-Xin Zhao,
• Lian-Jun Liu and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 726–731, doi:10.3762/bjoc.8.81

• type of axially chiral ligand 7 with an N-naphthyl framework (Figure 2) instead of traditional binaphthyl framework [15]. Their palladium complexes 8 showed high stereoselectivities in asymmetric allylic arylations to achieve the kinetic resolution of Morita–Baylis–Hillman adducts, affording up to 99

• with an axially chiral N-aryl framework are currently in progress, and their applications in asymmetric catalysis are also undergoing. Chiral NHC–Au(I) complexes. Axially chiral oxazoline–carbene ligands and their palladium complexes. The coordination study of the NHC precursor (Sa,S)-7aa with metal

Intramolecular hydroamination of alkynic sulfonamides catalyzed by a gold–triethynylphosphine complex: Construction of azepine frameworks by 7-exo-dig cyclization

• Hideto Ito,
• Tomoya Harada,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2011, 7, 951–959, doi:10.3762/bjoc.7.106

• have geminal disubstitution or ring fusion within a linker chain connecting the attacking nitrogen atom and the alkyne moiety. It should be noted, however, that 7-“endo”-dig cyclizations of (o-alkynyl)phenylacetamides and a diynamide were achieved with gold and palladium complexes [39][46][52][53], and

Highly efficient gold(I)-catalyzed Overman rearrangement in water

• Dong Xing and
• Dan Yang

Beilstein J. Org. Chem. 2011, 7, 781–785, doi:10.3762/bjoc.7.88

• catalysis under very mild conditions [3][4][5][6][7]. Asymmetric induction has been achieved with certain types of transition metal catalysts (e.g., palladium complexes) in combination with chiral ancillary ligands [8][9][10][11][12][13]. However, although a large number of late transition metal catalysts

A convenient catalyst system for microwave accelerated cross- coupling of a range of aryl boronic acids with aryl chlorides

• Matthew L. Clarke,
• Marcia B. France,
• Jose A. Fuentes,
• Edward J. Milton and
• Geoffrey J. Roff

Beilstein J. Org. Chem. 2007, 3, No. 18, doi:10.1186/1860-5397-3-18

• for aryl chloride activation, including diphosphine-Pd catalysts,[7] mono-phosphine Pd catalysts, [8][9] cyclometallated Pd precursors,[10] and potentially hemi-labile bidentate ligands. [11][12][13][14][15] Some years ago, we demonstrated that the palladium complexes formed from the amine-phosphine