Über Pterinchemie 23. Mitteilung [1]. Radikalbildung während der Oxydation von Tetrahydrofolsäure und 5,6,7,8-Tetrahydropterin

EPR. investigations show the existence of one-electron oxidation of 5,6,7,8-tetrahydropterine and tetrahydrofolic acid resulting in unstable cationic radicals of red color which are trapped at liquid nitrogen temperature.     

Über Pterinchemie. 69 Mitteilung [1]. Konformationsanalyse von 5,6,7,8-Tetrahydropteroinsäure und 5,6,7,8-Tetrahydro-L-folsäure

Conformational analysis of 5,6,7,8-tetrahydropteroic acid and 5,6,7,8-tetrahydro-L -folic acid In the 360-MHz-¹H-NMR.-spectrum of (6R, S)-9,9-dideuterio-5, 6, 7, 8-tetrahydropteroic acid (racemic) (XIII) (AMX-System, Fig. 4) and (6R, S)-9,9-dideuterio-5, 6, 7, 8-tetrahydro-L -folic acid (diastereomeric) (XVI) the H_a–C(6) and H_a–C(7) show a vicinal coupling constant of 6,7 Hz and the H_a–C(6) and H_e–C(7) one of 3,2 Hz. The first coupling constant provides evidence for an approximate trans-diaxal arrangement of H_a–C(6) and H_a–C(7), and the second for a gauche conformation of H_a–C(6) and H_e–C(7). The tetrahydropyrazine ring in the racemic 5, 6, 7, 8-tetrahydropteroic acid (III) and in the diastereomeric 5, 6, 7, 8-tetrahydro-L -folic acid (XVII) exists therefore in a half-chair conformation with a pseudoequatorial position of the side chain at C(6) (Fig.5).     

Über Pterinchemie. 68 Mitteilung [1]. Regiospezifische Deuterierungen von Folsäure

Regiospecific deuteriation of folic acid Introduction of a nitroso function at the N (10)-position of folic acid activates the C(9)-hydrogen atoms in such a way, that the exchange of H with D at this position, in NaOD-solution, is extremely facilitated. This fact is utilized in the synthesis of 9,9-dideuterio-folic acid (IV), 7,9,9-trideuterio-folic acid (VII) and 7-deuterio-folic acid (IX). These three products are necessary for the ¹H-NMR.-spectroscopical determination of the conformation of 5,6,7,8-tetrahydrofolic acid and its derivatives.     

Über ein neues Verfahren zur Herstellung von. Acetylenverbindungen. Vorläufige Mitteilung

A new method for the preparation of acetylenes by reating α-halogeno- or α-sulfonyloxyketones with p-toluenesulfonylhydrazine is reported.     

Über Pterinchemie 75. Mitteilung Synthese von 7-Aminoxanthopterin

Synthesis of 7-Aminoxanthopterin 7-Aminoxanthopterin (II) is obtained in good yield and purity by the transformation of isomer-free xanthopterin-7-carboxylic acid (I) with NH₃ followed by oxidation with MnO₂. The Frontier Orbital Theory contributes to a better understanding of the reaction pathway.     

Über Pterinchemie. 56. Mitteilung. Die Kristallstruktur von Xanthopterin-hydrochlorid

The crystal structure of xanthopterine-hydrochloride. The crystal structure of the title compound, a pterine, has been determined by X-ray analysis (direct methods) and refined with 1332 structure amplitudes to R = 0.027. The crystal system is monoclinic, space group P2_1/c, with unit cell dimensions a = 7.942, b = 8.417, c = 12.076 Å, β = 93.77°. The molecule is protonated at the N(1)-position. The angle between the planes of the pyrimidine and pyrazine rings is 2.02°.     

Über Chalkogenolate. 79. Untersuchungen über N-Hydroxydithiocarbamidsäure 1. Darstellung und Eigenschaften von N-Hydroxydithiocarbamaten und von Hydroxylammoniumdithiocarbamat

On Chalcogenolates. 79. Studies on N-Hydroxy Dithiocarbamic Acid. 1. Preparation and Properties of N-Hydroxy Dithiocarbamates and of Hydroxylammonium Dithiocarbamate In the presence of the corresponding hydroxide the reactions between hydroxylamine and carbon disulfide lead to N-hydroxy dithiocarbamates and [H₃NOH][S₂C? NH₂], respectively. The unstable compounds have been characterized by different methods.     

Neue Verfahren zur Herstellung von 21-Fluorsteroiden. Über Steroide. 232. Mitteilung

New methods for the preparation of 21-fluoro-steroids. 21-Fluoro-20-oxosteroids are obtained either by reacting a 21-diazo-20-oxo-steroid with hydrofluoric acid or by subjecting a 21-mesyloxy-20-oxo-steroid to reduction with the radical anion derived from lithium and biphenyl, followed by treatment of the resulting enolate with perchloryl fluoride.     

Über Chalkogenolate. 132. Untersuchungen über Rhodanine 3. Darstellung und Charakterisierung von Thiorhodanin und 5-Methylthiorhodanin. Versuche zur Herstellung von Trithiopyruvinsäure

On Chalcogenolates. 132. Studies on Rhodanines. 3. Synthesis and Characterization of Thiorhodanine and 5-Methyl Thiorhodanine. Attempts to Prepare Trithiopyruvic Acid The reactions of rhodanine and 5-methyl rhodanine with P₄S₁₀ and with Lawesson reagent yield the title compounds, which have been characterized with electron absorption, ¹H and ¹³C NMR, infrared, and mass spectra. Attempts to synthesize trithiopyruvic acid by use of different procedures were not successful.     

Über Pterinchemie. Mitteilung. Die Kristallstruktur von 5,6,7-Trimethyl-5,6,7,8-tetrahydropterindihydrochlorid-monohydrat

The crystal structure of 5,6,7-trimethyl-5,6,7,8-tetrahydropterine-dihydrochloride-monohydrate The crystal structure of the title compound has been determined by X-ray analysis (direct methods) and refined with 947 structure amplitudes to R = 0.026. The crystal system is orthorhombic, space group Pna2₁, with unit cell dimensions a = 14.081, b = 14.623, c = 6.773 Å. The molecule is protonated at the N(1)- and N(5)-position. The tetrahydropyrazine ring exists in a conformation in which C(6) deviates markedly from the mean plane of the other five atoms. The CH₃-groups at N(5) and C(6) possess a trans configuration with a pseudoaxial and an axial conformation respectively. The CH₃-groups at C(6) and C(7) in return possess the cis configuration, whereby the CH₃-group at C(7) occupies an equatorial conformation.     

Über Chalkogenolate. 121. Untersuchungen über N-Cyanomonothiocarbimidsäure 1. Darstellung und Eigenschaften von Alkalimetall-N-cyanomonothiocarbimaten

On Chalcogenolates. 121. Studies on N-Cyanomonothiocarbimic Acid. 1. Synthesis and Properties of Alkali Metal N-Cyanomonothiocarbimates The hitherto unknown N-cyanomonothiocarbimates M₂[SOC?N? CN] · H₂O, where M = Na, K, Rb, Cs, have been prepared by reaction of the corresponding alkali metal salt of cyanamide with COS. N-Cyanomonothiocarbimates react with sulfur to form the ion, which gives with an acid and with CH₃I the methyl compound . The reaction of the latter compound with H₂O₂ yields . All compounds have been characterized by means of diverse methods.     

Über Chalkogenolate. 108. Untersuchungen über Perthiocyansäure 1. Darstellung und Eigenschaften von Perthiocyanaten

On Chalcogenolates. 108. Studies on Perthiocyanic Acid. 1. Synthesis and Properties of Perthiocyanates The perthiocyanates have been prepared by different techniques. The compounds were characterized by means of diverse methods.     

Über Chalkogenolate. 99. Untersuchungen über Monothiocarbamidsäure 1. Darstellung und Eigenschaften von Monothiocarbamaten

On Chalcogenolates. 99. Studies on Monothiocarbamic Acid. 1. Synthesis and Properties of Monothiocarbamates The monothiocarbamates , and Ba[SOC? NH₂]₂ have been prepared and characterized by means of infrared, electron absorption, and mass spectra. The existence of the free monothiocarbamic acid was ascertained.     

Über Pterinchemie 18. Mitteilung [1] Monohydro- und Trihydropterin-Radikale

By oxydation of N(5)-methyl-6,7-diphenyl-5,6-dihydro- and N(5)-methyl-6,7-diphenyl-5,6,7,8-tetrahydro-pterine derivatives with perhydrol 8-monohydro- and 6,7,8-trihydro-pteridine radical cations are produced which are sufficiently stable for detection and structural elucidation by ESR. hyperfine analysis. The biological implications of these radicals for pteridine dependent hydroxylation and methyl transfer from 5-methylfolinic acid are discussed.