Über Chalkogenolate. 113 Umsetzung von Chloramin mit Kohlenstoffdisulfid und mit Methylestern von Dithiocarbamidsäuren

On Chalcogenolates. 113. Reactions of Chloramine with Carbon Disulfide and with Methylesters of Dithiocarbamic Acids The reactions of chloramine with CS₂ and with H₂N? CS? SCH₃, CH₃? NH? CS? SCH₃, and (CH₃)₂N? CS? SCH₃ have been studied. The reaction with the methylester of dithiocarbamic acid gives the known dimethyl perthiocyanate and the reaction with the methylester of N-methyldithiocarbamic acid leads to CH₃S? CS? N(CH₃)? C(?NCH₃)? SCH₃. The latter compound has been characterized by means of electron absorption spectra, infrared spectra, nuclear magnetic resonance spectra (¹H and ¹³C), and mass spectra.     

Zum Funktionsprinzip von Elektrodenmembranen mit dem Carboxyl-Ionophoren Monensin an Festkontaktsensoren

Summary The transport antibiotic Monensin acts as an electrogenic carrier in PVC membranes on Ag/AgCl/Pt solid contacts of disk electrodes. By way of experiments, it was possible to derive the existence of MonH · Na⁺ complexes from the operational principle of the electrode membranes. The non-physiological formation of protonized, positively charged complexes occurs owing to the high permittivity of o-NPOE as a plasticizer so that the ligand can become effective as an electrically neutral carrier. This is to be taken as the cause for Na⁺ to become the ion determining the potential also in measurements in the neutral point region; for it is the physiological effect of Monensin in thin biological membranes to mediate, as an exchange diffusion carrier, a Na ⁺-proton countertransport at a 11 ratio. This, however, is undesirable in measurements of the electromotive force (e.m.f.) since otherwise there would be no net charge transfer or formation of a potential difference at the lipophilic electrode membrane/aqueous measuring solution interface dependent upon the Na⁺ ion activity. The Monensin methylester was used as an electrically neutral ionophor for comparison. Likely, the lipophilic anion tetraphenyl borate causes the formation of MonH · Na⁺TPB^– complexes, whereby the neutral molecule Monensin, presumably due to intermolecular hydrogen bonds to the lipophilic anion, undergoes a further distortion in the coordination sphere entailing undesirable electrode characteristics. Under the influence of o-NPOE as a plasticizer, long-lived Na⁺ selective PVC membranes including Monensin or its methylester derivative, have been realized, which applied on disk electrodes produce reliable sensors for analysis.     

Determination of monomethylarsonic acid and dimethylarsinic acid by derivatization with thioglycolic acid methylester and gas—liquid chromatographic

An elegant method for the determination of monomethylarsonic acid and dimethylarsinic acid in biological materials is described. The methylarsenic acids are derivatized with thioglycolic acid methylester to yield lipophilic species, which can be determined by gas chromatography using a flame ionization detector or the more selective thermionic specific detector. The method permits the quick determination of methylarsenic acids in concentrations as low as 10 ng ml^-1 in urine or blood.     

Amidation of syndiotactic poly(2-methylallyl hydrogen carboxylate)

The amidation of syndiotactic polyacids and the ¹H- and ¹³C-NMR spectroscopic characterization of the resulting polyamides are described. The polyacids have been derived from syndiotactic poly(2-methylallyl alcohol) by esterification with cyclic dicarboxylic acid anhydrides, including N^α-protected aspartic acid anhydrides and glutamic acid anhydrides. The poly(hydrogen carboxylate) were in turn condensed with a series of amines, some of which possessed additional functional groups, e.g. (L)-1-phenylethylamine, histamine, and glycine methylester.     

Photochemical reactions—XXXV: Topochemical and nontopochemical control in the crystalline state photodimerization of a gibberellin enone.Crystal and molecular structure of 3-dehydro gibberellin A3 methyl ester

In connection with studies concerning the solid state photochemistry of the 3-dehydro gibberellin A₃ system 1, the crystal and molecular structure of the methylester 1b has been determined by X-ray analysis. The lattice parameters are a = b = 9.848 Å and c = 35.955 Å: the space group is P4₁2₁2. The final discrepancy factor R is 0. 081. The photoreactivity of 1b has been correlated with the molecular packing arrangement allowing to predict the constitution and stereochemistry of the formed main topodimer as 4. A mechanism for the simultaneous formation of the nontopochemical minor dimer as 3 is proposed.In earlier investigations² we showed the high photoreactivity of the 3-dehydro gibberellin A₃ type 1 in the crystalline state³ and the striking dependence of the photochemical reaction pathway on the kind of the substituent R. Whereas the free enone acid 1a upon n →π^* excitation of the enone chromophor undergoes intramolecular decarboxylation to the phenolic acid 2⁴ in high yield, the corresponding methylester 1b gives two primary dimers both arising from an intermolecular [2 + 2 ] photocycloaddition of the excited Δ¹ enone double bond to the terminal olefine function of an adjacent second molecule. From a multitude of regio- and stereoisomers the structures 3 and 4 have been proposed for the two dimers on the basis of physical data and stereochemical considerations.²     

Photochemische reaktionen—XXXII: Photochemie von gibberellin C; wege zur funktionalisierung von gibbanen in position 8 und 11

The n→π^* photochemistry of saturated diterpenoid ketones of the gibberellin C type 1 has been investigated. A Norrish type 1 cleavage leading to Δ⁷⁽¹¹⁾-unsaturated 7,8-seco-8-aldehydes 5 and 6, respectively, takes place as the main process. These secoaldehydes upon prolonged irradiation undergo intramolecular “crossed” photocycloaddition to the highly strained oxetanes 7 and 8. The oxetane methylester 8 represents a suitable key compound for proton catalyzed ring opening reactions under nucleophilic attack at C-8. In such a manner a series of 8α,11α-bifunctionalized gibbanes 12–20 have been prepared in good yields and under mild conditions.     

Synthesis of the stereoisomers of the methylesters of 3-isopropyl-5-methoxy-6-ketoheptanoic acid and of 2-methoxy-4-isopropylhexandioic acid

The four stereoisomers of 3-isopropyl-5-methoxy-6-ketoheptanoic acid methylester and those of 2-methoxy-4-isopropylhexandioic acid methylester were synthesized from R(?)- and S(+)-carvone. The combined data given provide a basis for specific enantiomer assignment to natural product degradation materials.     

New polyfunctional dendritic linear hybrids from terminal amine polyether oligomers (Jeffamine): synthesis and characterization

New dendritic polyether oligomers were synthesized from three different Jeffamines^® and characterized. This class of polyfunctional oligomers, bearing on their surface methylester, carboxylic acid, nitrile or amine groups, could be interesting modifying agents to change the properties of materials. The optimization of the iterative synthetic methods, through Michael addition, hydrolysis or hydrogenation, gave first and second generation dendritic structures in good yields.     

β-Cyclodextrin derivative as chiral carrier in membrane transport of some aromatic amino acids

The chiral functionalized β-cyclodextrin (heptakis (2,3,6-tri-o-acetyl)-β-cyclodextrin) was studied as an extraction receptor in liquid–liquid extraction and carrier through bulk liquid membrane for highlighting its ability to enantiomeric discrimination of some native aromatic amino acids (tryptophane, phenylalanine, and tyrosine) and methylester derivatives (tryptophane methylester hydrochloride, phenylalanine methylester hydrochloride, and tyrosine methylester hydrochloride). The receptor exhibited carrier ability for aromatic amino acids transport through chloroform liquid membrane, especially for l-amino acids form aiming at their separation. Active transport of amino acids assisted by the pH gradient was carried out. Additional, the circular dichroism measurements were performed to point out the enantiomeric discrimination of aromatic amino acids by functionalized β-cyclodextrin. The results showed that the structural properties of amino acids are an important parameter in extraction and transport experiments.     

Novel thiourea derivatives of α-amino acids and their oxorhenium(V) complexes

N-[(Dialkylamino)(thiocarbonyl)]benzimidoyl chlorides react with α-amino acid esters under formation of the corresponding N-[(dialkylamino)(thiocarbonyl)]benzamidines. Derivatives with glycine ethylester, HL(GlyOEt), cysteine methylester and S-benzyl protected cysteine ethylester, HL(S-Bzl-CysOEt), were prepared and isolated in crystalline form. The reaction with cysteine methylester yields the corresponding sulfur-bridged dimeric compound {HL(CysOMe)}₂.     

17O-NMR-spectroscopy as a tool for stereochemical analysis — Application to a diterpene-derivative

Summary Treatment of abietic acid methylester with Hg(OAc)₂/MeOH produces a dimethoxy derivative. The determination of the configuration at C-7 of this product by means of 1D- and 2D-NMR-spectroscopic methods is described. The results are verified by application of¹⁷O-NMR spectroscopy and comparison with well-established stereochemical dependencies of¹⁷O chemical shifts.

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¹⁷O-NMR-Spectroskopie zur stereochemischen Analyse. Anwendung auf ein Diterpen-Derivat

Zusammenfassung Umsetzung von Abietinsäuremethylester mit Hg(OAc)₂/MeOH führt zu einem Dimethoxyderivat. Die Bestimmung der Konfiguration am Zentrum C-7 erfolgt durch Anwendung von 1D- und 2D-NMR-Methoden. Die Resultate konnten durch¹⁷O-NMR-Spektroskopie aufgrund der bekannten stereochemischen Verschiebungsabhängigkeit bestätigt werden.

     

Anwendung von 2D-NMR-Techniken zur Analyse komplexer Spektren. Maleopimarsäuremethylester

A combination of 2D-NMR-techniques including 2D-J-resolved spectroscopy, SECSY and¹H-¹³C-shift correlation is used to assign the¹H- and¹³C-spectrum of Maleopimaric acid methylester [17,19-Dinoratis-15-ene-4,13,14-tricarboxylic acid 4-methylester, 16-(1-methylethyl)cyclic-13,14-anhydrid (4, 8, 12)] (1).

     

Metallkomplexe des Benzoyldithioessigsäuremethylesters und des N-Benzoylamino-dithiokohlensäureethylesters: Darstellung und Charakterisierung,ESCA- und EPR-Untersuchungen [1]

Metal Complexes of the Methylester of Benzoyldithioacetic Acid and the Ethylester of N-Benzoylamino-dithiocarbonic Acid: Preparation and Characterization, ESCA and EPR Investigations Neutral bis-complexes of the methylester of benzoyldithioacetic acid ( 1 ) with Ni^II, Pd^II, Cu^II, Zn^II and Pb^II were prepared as well as the tris-complex with Co^III. They are compared with corresponding complexes of the aza-isosteric ester ligand N-benzoylamino-dithiocarbonic acid ethylester (Ni^II, Pb^II). It turns out from IR, ESCA and (Cu^II/ 1 )-EPR data that both ligands chelate via O and S of its deprotonated forms with the exception of the lead complex of 1 , which contains the ligand monodentate and O-bound.     

Chiral Phosphine Ligands from Amino Acids. II. A Facile Synthesis of Phosphinoserines by Nucleophilic Phosphination Reactions – X‐Ray Structure Analyses of Ar2P–CH2–CH(NHBOC)(COOMe) (Ar = Ph,m‐xylyl)

Phosphino derivatives of serine R₂P–CH₂–CH(NHBOC)(COOMe) ( 2 a – 2 d ) have been obtained in high yield by nucleophilic phosphination of N‐(tert.butoxycarbonyl)‐3‐iodo‐L‐alanine methylester with secondary phosphines R₂PH (R = Ph, 2‐tolyl, 3,5‐xylyl, cyclohexyl) in DMF using potassium carbonate as the base. Deprotection of 2 b with HCl affords the amino acid ester hydrochloride [2‐Tol₂P–CH₂–CH(NH₃)(COOMe)]⁺Cl^– ( 3 a ). The X‐ray structures of 2 a (space group P2₁/n) and 2 c (space group P 1) have been determined. The two enantiomers of 2 a or 2 c are interconnected by N–H…O hydrogen bridges forming dimers in the solid state.     

Characterization of p-hydroxybenzoic acid methylester physi- and chemiadsorbates on silica by IR and UV-spectroscopy

Physiadsorbates and chemiadsorbates of p-hydroxybenzoic acid methylester (pHBAME) on colloidal and porous silicas were studied by IR and UV spectroscopy. In the IR spectra of self-supporting discs of the adsorbates, typical features were detected which allow differentiation between the physi- and the chemiadsorbed state: a strong absorption band at 1417 cm^–1 characterizes the chemiabsorbate. Dehydration by annealing and rehydration of the adsorbates proceeded also in a different way, indicated by absorption bands both in the carbonyl group and in the ring vibration frequency range. In the UV spectra the absorption maximum of the chemiadsorbate occured at 250 nm and that of the physiadsorbate at 255.5 nm (from cyclohexane suspensions of the adsorbates).Dedicated to Prof. Dr. Paul Heinz List on the occasion of his 65^th birthday.     

Simultaneous determination of four shanzhiside methylester derivatives in rabbit plasma by liquid chromatography/tandem mass spectrometry

A simple and sensitive high‐performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated for simultaneous determination of shanzhiside methylester and its three derivatives in rabbit plasma. The method showed good linearity and no endogenous material interfered with the marked compounds and internal standard (IS) capatol peaks. Samples were processed by acetonitrile precipitation. Chromatography was performed using a C₁₈ column (150 × 3.9 mm i.d., 4 µm). The mobile phase consisted of methanol and water (60:40, v/v) during a total run time of 7 min. The main mass parent ions and daughter ions pairs (m/z) for monitoring were: shanzhiside methylester, 429.0/267.4; 8‐O‐acetyl shanzhiside methylester, 470.9/411.3; loganin, 413.2/251.4; phloyoside II, 479.2/281.3; and IS 385.2/203.3. Finally, the method was applied to a pharmacokinetic study of rabbits following intravenous administration of iridoid glycosides extracted from traditional herb Lamiophlomis rotata. Copyright © 2012 John Wiley & Sons, Ltd.     

DERIVATE DER 1-PHENYL-1,3-DIHYDRO-2Λ5-BENZOPHOSPHOLSÄURE

Abstract

Synthesis, properties, NMR, and IR spectra of the chloride, fluoride, anhydride, and the methylester of the title compound as well as those of 1-phenyl-2-chloro-isophosphindoline are described.

Synthese, Eigenschaften, NMR-und IR-Spektren des Chlorids, Fluorids, Anhydrids und Methylesters der Titelverbindung sowie des 1-Phenyl-2-chlor-isophosphindolins werden beschrieben.     

Palladium(II) and platinum(II) complexes with N-substituted methionines

Summary As an approach to systems containing methionine residues, 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (HDh, dehydroacetic acid) was treated with L-methionine (MetH) or L-methionine methylester (MetM). By condensation at the acyl group and transfer of the phenolic hydrogen on the nitrogen atom, the related ligands DhMetH and DhMetM, were isolated, and form complexes of formula [MX₂(L)₂](M = Pd or Pt, L = DhMetM, X = Cl, Br or I; L = DhMetH, X = Cl or Br) and [MI₂(DhMetH)] with palladium and platinum dihalides. The reaction of the DhMetK carboxylate with MCl₂ in various media is discussed. Ligands and complexes were characterized by i.r. and n.m.r. (¹H and¹³C) spectroscopy and, in some cases, by thermogravimetric measurements. The ligands behave as monodentate sulphur donors, the 12 complexes showing atrans geometry except for [PtCl₂(DhMetH)₂], which is probably a mixture ofcis andtrans isomers.     

Nucleophile Addition von Triorganozinn-Anionen an Kohlenstoffdisulfid. III. Koordinationschemie der Triorganostannandithiocarbonsäurealkylester

Nucleophilic Addition of Triorganotin Anions to Carbon Disulfide. III. Coordination Chemistry of the Alkyl Esters of Triorganostannanedithiocarboxylic Acids As the first trialkyltin dithiocarboxylic ester, methyl tricyclohexylstannanedithiocarboxylate (L¹) was synthesized which forms with (η⁵-C₅H₅)Mn(CO)₂ · THF the complex CpMn(CO)₂L¹. In the same way, the triarylstannanedithiocarboxylic esters, L² = Ar₃SnCS₂R (Ar = phenyl, R = methyl, ethyl, allyl, isopropyl; Ar = o-, p-tolyl, R = methyl), react with irradiated metal carbonyls to give the neutral complexes W(CO)₅L² and CpMn(CO)₂L² in which L² is coordinated monodentately via the thiocarbonyl group. The methylester, L³ = Ph₃SnCS₂Me, forms with Re₂(CO)₉ · THF the dimetalcarbonyl complex Re₂(CO)₉L³ in which the ligand probably occupies the axial position.     

Partialsynthese eines bacteriophäophorbid-C-methylesters

The partial synthesis of a bacteriophaeophorbide c methylester starting from the chlorophyll a derivative chlorin e₆ trimethyl-ester is described.