Iminohydroxamato Early and Late Transition Metal Halide Complexes − New Precatalysts for Aluminoxane‐Cocatalyzed Olefin Insertion Polymerization

Krajete, Alexander; Steiner, Georg; Kopacka, Holger; Ongania, Karl‐Hans; Wurst, Klaus; Kristen, Marc O.; Preishuber‐Pflügl, Peter; Bildstein, Benno

doi:10.1002/ejic.200300405

Cited by 31 publications

(25 citation statements)

References 22 publications

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“…This compound was prepared using the procedure of Bildstein and coworkers [48], who reported its X-ray structure but no spectroscopic data. The data are included here for completeness.…”

Section: Preparation Of C 6 H 5 C(cl)n(26-i Pr 2 C 6 H 3 ) (2)mentioning

confidence: 99%

Synthesis and characterization of novel Pd(II) and Pt(II) complexes with 5-ring chelating iminoylcarbene ligands

Frøseth

Netland

Rømming

et al. 2005

Journal of Organometallic Chemistry

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“…This compound was prepared using the procedure of Bildstein and coworkers [48], who reported its X-ray structure but no spectroscopic data. The data are included here for completeness.…”

Section: Preparation Of C 6 H 5 C(cl)n(26-i Pr 2 C 6 H 3 ) (2)mentioning

confidence: 99%

Synthesis and characterization of novel Pd(II) and Pt(II) complexes with 5-ring chelating iminoylcarbene ligands

Frøseth

Netland

Rømming

et al. 2005

Journal of Organometallic Chemistry

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“…The planes of all the aromatic rings are tilted with respect to the O-N-C-N plane: in the neutral molecule the tilt angles are 70.5 (1) and 80.2 (1)°, while in the zwitterionic molecule these range from 87.6 (1) to 87.7 (1)°. This conformation is probably achieved to release the O-N-C-N backbone from the steric bulk of the methyl groups on the 2,6 position of the phenyl groups, and was also noticed in the structures of benzamidines studied by Krajete et al(2004).…”

Section: Be Best Described As O-h•••oand N-h•••n H-bonds the O-h•••omentioning

confidence: 70%

“…analogous crystal structure of a benzamidine system by Krajete et al (2004). In that case, however, the ligand dimerizes via a single H-bond.…”

Section: Be Best Described As O-h•••oand N-h•••n H-bonds the O-h•••omentioning

confidence: 99%

N¹,N²-Bis(2,6-dimethylphenyl)-N¹-hydroxyformamidineN,N′-bis(2,6-dimethylphenyl)-N-oxidoformamidinium dichloromethane solvate

2009

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Key indicators: single-crystal X-ray study; T = 200 K; mean (C-C) = 0.005 Å; R factor = 0.049; wR factor = 0.136; data-to-parameter ratio = 15.3.The title compound, 2C 17 H 20 N 2 OÁCH 2 Cl 2 , was obtained by Noxidation of the parent formamidine with m-chloro-peroxybenzoic acid (m-CPBA). This is the first use of the abovementioned synthetic route for the preparation of hydroxyamidines. The title compound crystallizes as a cyclic dimer resulting from the presence of O-HÁ Á ÁO and N-HÁ Á ÁN hydrogen bonds. Related literature ExperimentalCrystal data

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“…1). Compounds 1 to 25 (see Scheme S1 in the supplemental material) with introduction of substituents into the aromatic moieties (part A or B) were prepared by condensation of an intermediate amide with hydroxylamine (22,23). In order to ensure an appropriate coverage of lipophilic and electronic properties, the substituents were chosen rationally from all quadrants of a Craig plot (e.g., Hansch-Fujita versus constant) (24).…”

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confidence: 99%

New Insights into the Bacterial RNA Polymerase Inhibitor CBR703 as a Starting Point for Optimization as an Anti-Infective Agent

Zhu

Haupenthal

Groh

et al. 2014

Antimicrob Agents Chemother

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c CBR703 was reported to inhibit bacterial RNA polymerase (RNAP) and biofilm formation, considering it to be a good candidate for further optimization. While synthesized derivatives of CBR703 did not result in more-active RNAP inhibitors, we observed promising antibacterial activities. These again correlated with a significant cytotoxicity toward mammalian cells. Furthermore, we suspect the promising effects on biofilm formation to be artifacts. Consequently, this class of compounds can be considered unattractive as antibacterial agents. Bacterial RNA polymerase (RNAP) is essential for bacterial growth and survival and is thus an attractive target for drug development (1, 2). Along with the recently FDA-approved fidaxomycin (3), the rifamycins, applied as first-line antituberculosis drugs, are the only RNAP inhibitors that are in clinical use (2). However, similarly to other anti-infectives, the use of rifamycins resulted in the occurrence of resistant bacterial strains (1, 4-7), which represents a remarkable threat to public health (8, 9). Consequently, there is a need to focus on novel promising inhibitors. Recently, interesting peptidic and peptidomimetic (10-12) as well as nonpeptidic (13-18) small-molecule RNAP inhibitors have been described. Another example is CBR703 (Fig. 1), whose mechanism of action is reported to be different from that of the rifamycins (19,20). This compound has been identified in a highthroughput screening searching for small-molecule inhibitors of RNAP (19). Two more-potent analogs in that report reveal the potential of optimizing CBR703 by structural enlargement. Furthermore, pursuing the hypothesis that RNAP is of particular importance for bacterial survival in biofilms, Villain-Guillot et al. showed CBR703 to significantly reduce Staphylococcus epidermidis biofilm mass (21). We therefore considered CBR703 to be a promising starting point for drug development. Consequently, we focused on CBR703 to perform systematic modifications on its core structure, aiming to obtain a more appropriate starting point for further structural optimization.Detailed information concerning the materials and methods used in synthesis and biology can be found in the supplemental material.In total, 30 final compounds and 24 intermediates were obtained and tested for Escherichia coli RNAP inhibition and their ability to inhibit the growth of E. coli TolC (see Table S1 to S3 in the supplemental material). According to their structures, the synthesized derivatives can be divided into three groups with modifications in part A, B, or C (Fig. 1). Compounds 1 to 25 (see Scheme S1 in the supplemental material) with introduction of substituents into the aromatic moieties (part A or B) were prepared by condensation of an intermediate amide with hydroxylamine (22, 23). In order to ensure an appropriate coverage of lipophilic and electronic properties, the substituents were chosen rationally from all quadrants of a Craig plot (e.g., Hansch-Fujita versus constant) (24). The results (see Table S1) showed that compound...

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Iminohydroxamato Early and Late Transition Metal Halide Complexes − New Precatalysts for Aluminoxane‐Cocatalyzed Olefin Insertion Polymerization

Cited by 31 publications

References 22 publications

Synthesis and characterization of novel Pd(II) and Pt(II) complexes with 5-ring chelating iminoylcarbene ligands

Synthesis and characterization of novel Pd(II) and Pt(II) complexes with 5-ring chelating iminoylcarbene ligands

N¹,N²-Bis(2,6-dimethylphenyl)-N¹-hydroxyformamidineN,N′-bis(2,6-dimethylphenyl)-N-oxidoformamidinium dichloromethane solvate

New Insights into the Bacterial RNA Polymerase Inhibitor CBR703 as a Starting Point for Optimization as an Anti-Infective Agent

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Iminohydroxamato Early and Late Transition Metal Halide Complexes − New Precatalysts for Aluminoxane‐Cocatalyzed Olefin Insertion Polymerization

Cited by 31 publications

References 22 publications

Synthesis and characterization of novel Pd(II) and Pt(II) complexes with 5-ring chelating iminoylcarbene ligands

Synthesis and characterization of novel Pd(II) and Pt(II) complexes with 5-ring chelating iminoylcarbene ligands

N1,N2-Bis(2,6-dimethylphenyl)-N1-hydroxyformamidineN,N′-bis(2,6-dimethylphenyl)-N-oxidoformamidinium dichloromethane solvate

New Insights into the Bacterial RNA Polymerase Inhibitor CBR703 as a Starting Point for Optimization as an Anti-Infective Agent

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Product

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N¹,N²-Bis(2,6-dimethylphenyl)-N¹-hydroxyformamidineN,N′-bis(2,6-dimethylphenyl)-N-oxidoformamidinium dichloromethane solvate