HYDROCHLORINATION OF 2,3-ACETYLENIC ACIDS WITH THIONYL CHLORIDE IN DIMETHYLFORMAMIDE

ABSTRACT

The reaction of 2,3-acetylenic acids (1a–d) with thionyl chloride in DMF under mild conditions gave E,Z-3-chloro-2-alkenoic acids (2a–d) or esters (3a–d) depending on treating the reaction mixture with either water or alcohols.     

Resolution of D,L-Dansyl Amino Acids by HELC with a Cu(II)-L-proline Eluant

Abstract

Highly fluorescent dansyl derivatives of D and L amino acids were resolved on a reversed phase column by using an aqueous eluant containing copper(II)-L-proline.     

Simultaneous Estimation of 4-O-Methyl-D-Glucuronic Acid and Other Uronic Acids By Gas-Liquid Chromatography

Abstract

Uronic acids in polysaccharides may be reduced by reaction of the propionated methyl ester with lithium borohydride in tetrahydrofuran. After hydrolysis and reduction of the monosaccharides the acetylated alditols may be separated by gas-liquid chromatography on a column of butanediol succinate. The method permits the simultaneous estimation of 4-O-methyl-D-glucuronic acid, glucuronic and galacturonic acids.     

N-SULPHONYL PYRIDINIUM SALTS IN THE HETARYLATION REACTION

Abstract

Hetarylation of organic CH-acids by a sumultaneous action on them with N-heteroaromatic compounds and acylating agents, carboxylic chlorides and chlorides of acids of phosphorus (III and V) is known.     

Thin-Layer Chromatography of Bile Alcohols,Bile Acids and Conjugated Bile Acids

Abstract

Thin-layer chromatography of bile alcohols, bile acids and bile acid conjugates has been reviewed. Particular emphasis has been placed on the separation of the glycine and taurine conjugated bile acids as a class and as individual compounds, and on the isolation of bile alcohols and C₂₇ bile acids diastereo-isomeric at C-25.     

Analysis of Hydroxybenzoic Acids by High Pressure Liquid Chromatography

Abstract

Good separation of a range of hydroxybenzoic acids was achieved by HPLC on a μBondapak phenyl column using 5% v/v acetic acid in water as the eluting solvent.     

NMR-Spektren einiger Benzylidenbarbitursäurederivate

The NMR-Spectra of substituted benzylidene barbituric acids, benzylidene dimethylbarbituric acids and some 1,4-and 1,3-cycloaddition products are reported. The signals of the olefinic protons and the N–CH₃-signals depend on the conformation of the compounds. The NMR-Spectra of the anions are also given.

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Mit 1 Abbildung

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R. Bednar, O. E. Polansky undP. Wolschann, Z. Naturforsch.30 b, 582 (1975).     

Methods of Synthesis of Organophosphorus Nitro-Compounds and Aminoalkylphosphonic Acids

Abstract

Reduction of nitroorganophosphorus compounds is a way to synthesize functionally substituted aminoalkylphosphonic acids.

Experimental methods of synthesis of nitroorganophosphorus compounds were proposed: by nitration vinylphos-phonates by nitrogen oxides; interaction between phosphorus-containing compounds with active hydrogen atom and conjugated nitroalkenes; condensation of nitroalkanes with vinylpnosphonates and acylphosphonates. The dependence of the reaction direction on the structure of reacting compounds and experimental conditions was shown.     

Zur Reaktion von 1,4-Pentadien-3-onen mit Malonestern

Zusammenfassung Diarylpentadienone (1) ergeben mit Malonester (2) entweder 2,6-Diaryl-4-oxo-5-hexen-1,1-dicarbonsäurediester (3) oder 2,6-Diaryl-4-oxo-cyclohexan-1,10dicarbonsäurediester (5). Das sterische Verhalten von3 und5 wird durch IR- und NMR-Untersuchungen ermittelt sowie die sterischen Gesichtspunkte der Gesamtreaktion diskutiert. Weiter werden die Bedingungen zur Darstellung — besonders die Verwendbarkeit verschiedener basischer Katalysatoren — untersucht.

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On the reactions of 1.4-pentadien-3-ones with malonates

Diarylpentadienones (1) react easily with malonates (2) to give diesters of 2.6-diaryl-4-oxo-5-hexen-1.1-dicarboxylic acids (3) and of 2.6-diaryl-4-oxo-cyclohexane-1.1-dicarboxylic acids (5), resp. The steric behaviour of3 and5 is established by IR- and NMR-spectroscopy and the influence of some basic catalysts on the reaction products is discussed.

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Auszugsweise vorgetragen anläßlich der 75-Jahr-Feier des VöCh, Wien, 17. bis 20. Mai 1972.     

Convenient Synthesis of Pyrrole‐ and Indolecarboxylic Acid tert‐Butylesters

Abstract

The tert‐butylesters of pyrrole‐ and indolecarboxylic acids are readily accessed by reacting the appropriate carboxylic acids with N,N‐dimethylformamide di‐tert‐butyl acetal.     

Synthesis of Arylglyoxylic Acids and Their Collision-Induced Dissociation

Abstract

A variety of substituted arylglyoxylic acids (2a?g) were synthesized via oxidation of the corresponding aryl-methylketones (1a–e) using selenium dioxide or Friedel–Crafts acylation of phenol (3) with ethyl chlorooxoacetate and further transformations. It was found that the arylglyoxylic acids (2) undergo facile unimolecular dissociation with loss of carbon monoxide to give the corresponding arylcarboxylic acids (7) under collisionally induced mass spectrometric conditions.     

STEREOCHEMISTRY AND KINETICS OF THE ALKOXY-ALKOXY EXCHANGE IN SULPHINATES

Abstract

The present communication will describe theresuls of our studies on the stereochemistry and kinetics of the transesterification reaction of aromatic sulphinic acid esterscatalysed by strong acids.     

Improved Yields in the Synthesis of Spin‐Labeled Fatty Acids

Abstract

Paramagnetic amide side products (6a–g) have been isolated from the reaction mixture in the synthesis of spin‐labeled fatty acids of the doxyl type. After their hydrolysis to the corresponding acid, 7, the overall yield of spin‐labeled fatty acids is significantly increased compared with published procedures.     

Polarographic Reduction of Aromatic Arsonic and Arsinic Acids

Abstract

The polarographic reduction of the aromatic arsonic acids; phenyl-, benzyl-, and 2-phenylethylarsonic acid; and the aromatic arsinic acids; diphenyl-, dibenzyl-, and di-2-phenylethylarsinic acid by differential pulse polarography is described.     

Synthesis of Benzylphosphonous Acids VIA Direct Amidoalkylation of Hypophosphorous Acid

Abstract

In the communication presented here we wish to report on a convenient synthetic route to the yet unknown aminobenzylphosphonous acids 3a-3i.     

Synthesis of Monocyclic β‐Lactams via Cyclodehydration of β‐Amino Acids Using POCl3

Abstract

β‐Lactams 2 have been synthesized through a convenient use of POCl₃ via cyclodehydration of β‐amino acids 1.     

1-Chlormethylisatin—ein neues reagens zur Identifizierung von Carbonsäuren

Zusammenfassung 1-Chlormethylisatin (2) reagiert mit den Salzen von Monobzw. Dicarbonsäuren in Wasser—Dimethylformamid leicht zu 1-Isatinylmethyl- bzw. Di-(1-isatinylmethyl)estern3 bzw.4. 68 derartige Ester wurden dargestellt und tabelliert; sie sind zur Identifizierung von Carbonsäuren bestens geeignet.

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1-Chloromethylisatin—a new reagent for identifying carboxylic acids

1-Chlormethylisatin (2) reacts with salts of mono- resp. dicarboxylic acids in water—dimethylformamide easily to yield 1-isatinylmethyl- resp. di(1-isatinylmethyl)esters3 resp.4. 68 of these esters were synthesized and tabulated; they are a useful means for characterizing carboxylic acids.

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Herrn Prof. Dr.E. Ziegler zum 60. Geburtstag gewidmet.     

Pyrolysis of Amino Acid Derived Stabilised Ylides as a Route to Chiral Acetylenic Amines and Amino Acids and Gaba Analogues

Abstract

We recently reported the pyrolysis of stabilised ylides as a method for overall conversion of carboxylic acids to homologous acetylenic esters and terminal alkynes.^1,2 This has now been applied successfully to amino acids. A wide range of alkoxycarbonyl protected amino acids have been converted to the stable crystalline ylides 1. These have been fully characterised, and upon FVP, eliminate Ph₃PO to afford the protected acetylenic amino acids 2 in good yield and without significant racemisation. Subsequent reactions of these extremely versatile intermediates have been used to gain access to a wide variety of chiral amine and amino acids of great interest as potential selective enzyme inhibitors and components for modified peptide structures.     

The Study of UV and VIS Absorption Spectra of the Complexes of Amino Acids with Ninhydrin

Abstract

The analysis of amino acids with post column derivatization using ninhydrin is usually carried out with automatic analyzers at wavelengths of 570 nm (for the quantitation of α-amino acids) and 440 nm (for the imino acids), or at only one wavelength, 520 nm, for the total acid content. The α-amino acids are reported to give an absorption maximum at 570 nm, after complex formation with ninhydrin; and α-imino acids have a γ at 440 nm, 520 nm is a compromise wavelength.

This paper presents a study of the absorption of the complexes of amino acids with ninhydrin between 275 and 700 nm. Two new wavelengths are suggested for use, 290 and 404 nm.

In the near UV (290 nm) all the tested acids show a common absorption maximum and good sensitivities. In the visible region at 404 nm, the sensitivities of the α-amino acids are very similar to those observed at 570 nm. At 520 nm the αamino acids have the lowest sensitivities.

The α-imino acids (proline and oxyproline) show absorption maxima only at 290 nm; after that their sensitivities decrease with increasing wavelength.

The paper offers some practical hints on changing the detector wavelength, and to adapt the HPLC's detector to work at one of these two, newly suggested, bands (290 or 404 nm).     

Gas Chromatography of Alpha-Keto Acids with A Sensitive and Selective Detector

Abstract

Gas chromatography of α-keto acids has been performed with high sensitivity by converting the acids to the trimethylsilyl derivatives of the quinoxalones derived from them and using a rubidium sulfate flame detector. Quantitative determinations have been made with the use of alkyl cyanides as internal standards.