Benzo[1,2‐<i>h</i>:4,3‐<i>h′</i>]dichinolin („1,14‐Diaza[5]helicen”︁): Synthese, Struktur und Eigenschaften

Staab, Heinz A.; Zirnstein, Michael A.; Krieger, Claus

doi:10.1002/ange.19891010120

Cited by 22 publications

(6 citation statements)

References 9 publications

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“…Coupling of the protected 2,2Ј-dimethoxy-1,1Ј-diphenyl-4-carboxylic acid 9 with tren was most conveniently accomplished using N,NЈ-carbonyldiimidazole (CDI). [18] For comparative complexation studies, simple bidentate ligands 14 and 15 were also prepared ( Figure 2). Sulfonation, using H 2 SO 4 /oleum, of tripod 11 and of bidentate ligand 14 afforded the water-soluble products 12 and 15, respectively.…”

Section: Synthesis Of Ligandsmentioning

confidence: 99%

Towards New Iron(III) Chelators: Synthesis and Complexing Ability of a Water-Soluble Tripodal Ligand Based on 2,2′-Dihydroxybiphenyl Subunits

Baret

Beaujolais

Béguin

et al. 1998

Eur. J. Inorg. Chem.

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Section: Synthesis Of Ligandsmentioning

confidence: 99%

Towards New Iron(III) Chelators: Synthesis and Complexing Ability of a Water-Soluble Tripodal Ligand Based on 2,2′-Dihydroxybiphenyl Subunits

Baret

Beaujolais

Béguin

et al. 1998

Eur. J. Inorg. Chem.

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“…Apart from varying the substituents of DMAN, several proton‐chelating compounds with backbones other than naphthalene have been synthesized. The interaction of two basicity centers has also been achieved by aromatic spacers such as fluorene,22 heterofluorene,23 phenantrene,24 biphenyl25 or helicene26 moieties. Potáček et al.…”

Section: Introductionmentioning

confidence: 99%

“…[20] This structure motive was recently further modified by Shaffer et al [21] Apart from varying the substituents of DMAN, several proton-chelating compounds with backbones other than naphthalene have been synthesized. The interaction of two basicity centers has also been achieved by aromatic spacers such as fluorene, [22] heterofluorene, [23] phenantrene, [24] biphenyl [25] or helicene [26] moieties. Potµc ˇek et al reported on the preparation of caged proton sponges with a non-aromatic skeleton.…”

Section: Introductionmentioning

confidence: 99%

Superbasic Alkyl‐Substituted Bisphosphazene Proton Sponges: Synthesis, Structural Features, Thermodynamic and Kinetic Basicity, Nucleophilicity and Coordination Chemistry

Kögel

Xie

Baal

et al. 2014

Chemistry A European J

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Herein we describe an easily accessible class of superbasic proton sponges based on the 1,8-bisphosphazenylnaphthalene (PN) proton pincer motif and P-alkyl substituents ranging from methyl (TMPN) to n-butyl (TBPN), isopropyl (TiPrPN) and cyclopentyl (TcyPPN). These neutral bases with a pK(BH)(+) value (MeCN) of ~30 were accessible via a Kirsanov condensation using commercially available 1,8-diaminonaphthalene, and in case of TMPN and TBPN, simple one-pot procedures starting from trisalkylphosphanes can be performed. Furthermore, the known pyrrolidinyl-substituted superbase TPPN previously synthesized via a Staudinger reaction could also be prepared by the Kirsanov strategy allowing its preparation in a larger scale. The four alkyl-substituted proton sponges were structurally characterized in their protonated form; molecular XRD structures were also obtained for unprotonated TiPrPN and TcyPPN. Moreover, we present a detailed description of spectroscopic features of chelating bisphosphazenes including TPPN and its hyperbasic homologue P2-TPPN on which we reported recently. The four alkyl-substituted superbases were investigated with respect to their basic features by computational means and by NMR titration experiments revealing unexpectedly high experimental pK(BH)(+) values in acetonitrile between 29.3 for TMPN and 30.9 for TBPN. Besides their thermodynamic basicity, we exemplarily studied the kinetic basicity of TMPN and TPPN by means of NMR-spectroscopic methods. Furthermore, the competing nucleophilic versus basic properties were examined by reacting the proton sponges with ethyl iodide. Insight into the coordination chemistry of chelating superbases was provided by reacting TMPN with trimethylaluminum and trimethylgallium to give cationic complexes of Group XIII metal alkyls that were structurally characterized.

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“…Therefore, IV-me was submitted to an acetylation using N-acetylimidazole. 26 Reversed-phase HPLC revealed the formation of a product (IV-me-ac) which eluted at 16.40 min (HPLC system A, with pure methanol as the eluent after 11.2 min). Simultaneous UV detection at two different wavelengths (340 and 356 nm) showed an identical absorbance ratio (peak area 340/peak area 356) of IV-me-ac (2.40) to IV-me (2.50) and IV (2.55).…”

Section: Tsp Hplcfmsmentioning

confidence: 99%

Characterization of oxidized and glucuronidated metabolites of retinol in monkey plasma by thermospray liquid chromatography/mass spectrometry

Eckhoff

Wittfoht

Nau

et al. 1990

Biol. Mass Spectrom.

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Eight metabolites of retinol were isolated by high-performance liquid chromatography (HPLC) from the plasma of the non-human primate Macaca fascicularis after acute exposure to 150,000 IU of vitamin A per kilogram body weight. After enrichment and further chromatographic purification, the metabolites were reinjected individually into a second HPLC system which was connected on-line by a thermospray interface to a mass spectrometer operated in the positive ionization mode. Six retinoids were identified by (i) a comparison of their retention times with those of appropriate reference compounds in the two chromatographic systems and (ii) by comparison of their mass spectra with those of reference compounds. These retinoids were: 13-cis-4-oxoretinoic acid, all-trans-4-oxoretinoic acid, 13-cis-retinoic acid, all-trans-retinoic acid, all-trans-retinoyl beta-glucuronide and all-trans-retinyl beta-glucuronide. One further metabolite could be identified for the first time as all-trans-4-oxoretinoyl beta-glucuronide by its mass spectrum and, after treatment of the unknown metabolite with beta-glucuronidase, by its hydrolysis product all-trans-4-oxoretinoic acid. The molecular structure of one metabolite could not be elucidated. A major metabolic pathway of high-dose vitamin A in the non-human primate is apparently the oxidation of the primary alcohol group of retinol resulting in the formation of all-trans-retinoic acid. Subsequently, a broad spectrum of various metabolites of all-trans-retinoic acid, including beta-glucuronides and retinoids with a 13-cis configuration, appear in the plasma.

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Benzo[1,2‐h:4,3‐h′]dichinolin („1,14‐Diaza[5]helicen”︁): Synthese, Struktur und Eigenschaften

Cited by 22 publications

References 9 publications

Towards New Iron(III) Chelators: Synthesis and Complexing Ability of a Water-Soluble Tripodal Ligand Based on 2,2′-Dihydroxybiphenyl Subunits

Towards New Iron(III) Chelators: Synthesis and Complexing Ability of a Water-Soluble Tripodal Ligand Based on 2,2′-Dihydroxybiphenyl Subunits

Superbasic Alkyl‐Substituted Bisphosphazene Proton Sponges: Synthesis, Structural Features, Thermodynamic and Kinetic Basicity, Nucleophilicity and Coordination Chemistry

Characterization of oxidized and glucuronidated metabolites of retinol in monkey plasma by thermospray liquid chromatography/mass spectrometry

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