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 Chalkogenolate. 82 [1]. N-Hydroxycarbamate und Ester der N-Hydroxycarbamidsäure und -carbimidsäure

On Chalcogenolates. 82. N-Hydroxy Carbamates and Esters of N-Hydroxy Carbamic Acid and Carbamic Acid The reaction between hydroxylammonium chloride, CO₂, and the corresponding hydroxide leads to N-hydroxy carbamates Esters of N-hydroxy carbamic acid have been prepared by reaction of N-hydroxy carbamates with alkyl bromide. – At room temperature the ethyl ester decomposes and forms the ester of N-hydroxy carbimic acid HO? N?C(OC₂H₅)₂. The prepared compounds have been characterized by different methods.     

Ein einfacher Zugang zu 3-Amino-nocardicinsäure. Modifikationen von Antibiotika. 17. Mitteilung [1]

A Simple Route to 3-Amino-nocardicinic Acid Starting from nocardicin A ( 1 ), a novel and efficient procedure for the preparation of 3-amino-nocardicinic acid ( 4 ) and its protected derivatives 6 and 8–11 is described.     

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 Chalkogenolate. 136 [1]. Alkylester der Cyanoameisensäure und der Cyanomonothioameisensäure

On Chalcogenolates. 136. Alkyl Esters of Cyanoformic Acid and of Cyanomonothioformic Acid By use of the phase transfer catalyst 18-crown-6 the esters CH₃O—CO—CN, C₂H₅O—CO—CN, C₂H₅S—CO—CN, and ⁿC₃H₇S—CO—CN have been prepared by reaction of the corresponding chloro compound with potassium cyanide. The prepared compounds have been characterized by means of electron absorption, infrared, nuclear magnetic resonance (¹H and ¹³C), and mass spectra.     

Über Chalkogenolate. 206 [1]. N-Thioacetyldithiocarbamate und Ester der N-Thioacetyldithiocarbamidsäure

On Chalcogenolates. 206. N-Thioacetyl Dithiocarbamates and Esters of N-Thioacetyl Dithiocarbamic Acid Thioacetamide reacts with carbon disulfide in the presence of KH to form via the tetrabutyl ammonium salt dark yellow N-thioacetyl dithiocarbamates M[S₂C? NH? CS? CH₃], where M = K, Rb, Cs. The salts as well as the methyl and ethyl ester have been characterized by means of electron absorption, infrared, nuclear magnetic resonance (¹H and ¹³C), and mass spectra. Attempts to synthesize N-thioacetyl dithiocarbamic acid were not successful.     

Azidiniumsalze. 8. Mitteilung [1]. Darstellung und Eigenschaften substituierter Chinolintriaza-trimethincyanine

The synthesis of triaza-trimethin-cyanine-tetrafluoroborates from 1-ethyl-2-azido-6-X-quinolinium-tetrafluoroborates and sodium azide is described. The visible spectra and the properties of the dyes are discussed.     

Steroide und Sexualhormone 233. Mitteilung [1]. Synthese von 4 stereoisomeren 1, 4-Oxido-3-oxa-A-homo-androstan-Derivaten

A synthesis of the four stereoisomeric 1,4-oxido-3-oxa-A-homo-androstane-derivatives 3 , 9 , 13 , and 19 is described, starting from the lactones 1 , 11 , and 15 .     

Calicen Hochpolare Dicyan-diphenyl-derivate [1] [2]. Vorläufige Mitteilung

Three dicyano-diphenyl-calicenes have been synthesized. Judged by the dipole moments, the uv. and nmr. data, there is appreciable charge separation in the ground states.     

Steroide und Sexualhormone. 239. Mitteilung [1]. Die Partialsynthese von Anhydroholantogenin

A synthesis of the title compound 4 , which had been isolated [2] in form of an amino glycoside from the leaves of Holarrhena antidysenterica is described, using 2 [1] as starting material.     

Über Chalkogenolate. 117 [1]. Untersuchungen über Guanidinodithioformiate 4. Kristall- und Molekülstruktur der Guanidinodithioameisensäure

On Chalcogenolates. 117. Studies on Guanidinodithioformates. 4. Crystal and Molecular Structure of Guanidinodithioformic Acid Guanidinodithioformic acid crystallizes with Z = 4 in the monoclinic space group P2₁ with cell dimensions a = 4.204(3) Å, b = 10.422(5) Å, c = 12.491(5) Å, β = 93.9(3)°. The crystal and molecular structure has been determined from single crystal X-ray data at 20°C and refined to a conventional R of 0.0242. The asymmetric part of the unit cell contains two molecules in the dipolar form with different conformation. The molecules have delocated double-bonds and are linked together by N? H···S hydrogen bridges.