Struktur-Wirkungs-Beziehungen bei Histaminanaloga, 20. Mitt. Absolute Konfiguration und histaminartige Wirkung der enantiomeren α-Methylhistamine

Structure-Activity Relationships of Histamine Analogues, XX: Absolute Configuration and Histamine-like Activity of the Enantiomeric α-Methylhistamines The synthesis of the enantiomeric α-methylhistamines (+)- 5 and (-)- 5 , the determination of the absolute configuration and the histamine-like activity of the enantiomers on the guinea-pig ileum (H₁) and atrium (H₂) are reported.     

Struktur-Wirkungs-Beziehungen bei Histaminanaloga, 22. Mitt. Absolute Konfiguration und histaminartige Wirkung der enantiomeren α, Nα-Dimethylhistamine

Structure-Activity Relationship of Histamine Analogues. XXII: Absolute Configuration and Histamine-like Activity of the Enantiomeric α, N^α-Dimethylhistamines The synthesis of the enantiomeric α, N^α-Dimethylhistamines (+)— 3 and (?)— 3 , the determination of the absolute configuration and the histamine-like activity of the enantiomers on the guinea-pig ileum (H₁) and atrium (H₂) are reported.     

Struktur-Wirkungs-Beziehungen bei Histaminanaloga, 21. Mitt. Synthese und Wirkung Nα-substituierter Histamine

Structure-Activity Relationships of Histamine Analogues, XXI: Synthesis and Pharmacology of N^α-Substituted Histamines N^α-Substituted histamines were synthesized and investigated with regard to their agonistic activity at histamine H₁ and H₂ receptors.     

Struktur-Wirkungs-Beziehungen bei Histaminanaloga, 24. Mitt. Absolute Konfiguration und histaminartige Wirkung der Enantiomere von 4-(2-Aminopropyl)-5-methyl-imidazol

Structure-Activity Relationships of Histamine Analogues, XXIV: Absolute Configuration and Histamine-Type Activity of the Enantiomers of 4-(2-Aminopropyl)-5-methylimidazole The resolution of 4-(2-aminopropyl)-5-methylimidazole (1) , the determination of the absolute configuration and the histamine-type activity of the enantiomers on the guinea pig ileum (H₁) and atrium (H₂) are reported.     

Zur Keto-Enol-Tautomerie bei heterocyclischen β-Ketocarbonsäureestern 3. Mitt.: Konfiguration und Konformation 2,6-dialkylsubstituierter β-Ketodicarbonsäureester

Keto-Enol-Tautomerism of heterocyclic β-Ketocarboxylic Acid Esters The configuration and conformation of 1-aza-, 1-oxa-, 1-thia- and 1-selena-cyclohexanone dicarboxylic acid esters has been studied by proton resonance spectroscopy. In the keto forms of these compounds, the substituents at C-2, -3, -5 and -6 have the following relative configuration: 2,6-/3,5-cis, 2,3-/5,6-trans. The preferred conformation of these ketones is the chair conformation in which all substituents have equatorial positions.     

Adduktbildung und Dimerisierung von α-Piperidinoacetonitril bei Umsetzung mit n-Butylmagnesiumchlorid. V. Mitt. über Umsetzungen von α-Aminonitrilen

Dimerisation of α-Piperidinoacetonitrile in the Reaction with n-Butylmagnesium chloride The reaction mechanisms which determine the course of the reaction between t- and n-butyl-magnesium chloride and α-piperidinoacetonitrile, have been studied. The formation of different quantities of the reaction products 3-amino-2,4-dipiperidinocrotononitrile and butyl-α-piperidinomethylketone can be explained on the basis of steric hindrace and also through the difference of nucleophilic activity of t- and n-butyl groups.     

α-Thiotetronsäuren, 1. Mitt.: Synthese und Eigenschaften von γ-Alkyliden-α-thiotetronsäuren

α-Thiotetronic Acids, I: Synthesis and Properties of γ-Alkylidene α-Thiotetronic Acids We report on the synthesis of the alkylidene α-thiotetronic acids 11 and 12a and a variety of their derivatives, starting with 2,3-dimethoxysuccinic thioanhydride ( 4 ) or diethyl 3-thioxoglutarate. The rhodium(II)-catalysed decomposition of the diazoketone 26 furnishes the reductone 12p and the aminoreductone 12r with the thietanone 27 as one of the by-products.     

Zyklische Harnstoffe, 1. Mitt.: Racemate und Enantiomere von Hexahydropyrimidin-2-onen: Synthese,Konfiguration und sedativ-hypnotische Wirkung

Cyclic Ureas, I: Racemates and Enantiomers of Hexahydropyrimidin-2-ones: Syntheses, Configurations and Sedative-hypnotic Activity The racemates and the enantiomers of the hexahydropyrimidin-2-ones 2a-2e which can be regarded as cyclic ureas are obtained from the racemates and the enantiomers of the barbiturates 1a-1e by reduction with LiAlH₄/AlCl₃. The enantiomers of 2a-2d , dextrorotatory in ethanol, possess S-configuration. - In a study with rats all cyclic ureas synthesized showed sedative-hypnotic activity. Some of the enantiomers exhibited marked enantioselective differences in their potency.     

Thion- und Dithioester, 48. Mitt. α,β-Ungesättigte Thioester in Diels-Alder-Reaktionen und Michael-Additionen

Thiono and Dithio Esters, XLVIII: α,β-Unsaturated Thio Esters in Diels-Alder Reactions and Michael Additions The reaction of cinnamic acid thio esters with different dienophiles leads to the formation of the Diels-Alder products 3 – 8 ; with lithium enolates the Michael adducts 11 and 13 were isolated.     

NMR-Spektroskopie an Heterocyclen, 6. Mitt. Favorskii-Umlagerung von α-Brom-β-methoxy-ketonen bei der Imidazol-Cyclisierung in flüssigem Ammoniak

NMR Spectroscopy of Heterocycles. VI: Favorskii Rearrangement of α-Bromo-β-methoxy Ketones During Imidazole Cyclisation in Liquid Ammonia. During imidazole synthesis with α-bromo ketones and formiminic ethyl ester in liquid ammonia α-alkylbutyric amides were obtained as by-products. Their formation is attributed to a Favorskii rearrangement. The compounds were investigated by NMR spectroscopy.     

Imidazolsynthesen, 7. Mitt.: Imidazole aus Iminoestern, α-Amino- oder α-Acylaminoketonen und flüssigem Ammoniak

Imidazoles from Iminoesters and α-Amino-or α-Acylaminoketones and Liquid Ammonia Substituted imidazoles 4 are obtained from iminoesters 1 and α-amino- 2 or α-acylaminoketones 3 in liquid ammonia under pressure.     

Addition von β-Dicarbonylverbindungen an 2-Acetyl-p-benzochinon, 3. Mitt.1): Untersuchung der Umsetzung mit α-Hydroxymethylencycloalkanonen

Addition of β-Dicarbonyl Compounds to 2-Acetyl-p-benzoquinone, III¹⁾: The reaction of α-hydroxymethylenecyclopentanone 2 with acetylquinone 1 yields the spiro-compound 3 . α-Hydroxymethylenecyclohexanone 7 gives the dibenzopyran 8 and the spiro-compound 9 as by-product. Compounds 3, 8 , and 9 are labile, rearrangement to 6 and 11 is examined by NMR spectroscopy. Acetylation of 6 and 11 yields 5 and 12 . With hydrochloric acid the spiro-compounds 6, 11 are rearranged to 16 and 17 , respectively.     

H2-Antihistaminika, 2. Mitt. Synthese und Pharmakologie α-substituierter Metiamid-Analoga

H₂-Antihistaminics, II: Synthesis and Pharmacology of α-Substituted Metiamide Analogues The synthesis of α-substituted 5-methyl-4- {2-[3-(methyl)thioureido]ethylthiomethyl}-1H-imidazoles 4 from α-substituted 4-methoxymethyl-5-methyl-1H-imidazoles 2 is described. The H₂-antihistaminic activity of the products is reported.     

Dithio- und Thionester, 57. Mitt.: Synthese N-geschützter β- und γ-Aminosäuredithioester und -thionester

Dithio and Thiono Esters, LVII: Synthesis of Dithio and Thiono Esters of N-Protected β- and γ-Amino Acids The N-Protected β-aminonitriles 1 were transformed into the imidoester or thiolimidoester hydrochlorides 2 or 3 according to Pinner and sulfhydrolyzed with H₂S to give the N-protected β-amino thiono esters 4 or dithio esters 5 . Alkylation of the amides 6 and thioamides 7 yields the iminium salts 8/9 and their sulfhydrolysis again 4/5 . By the first approach N-protected γ-amino nitriles 11 were converted into the γ-amino thiono esters 14 and dithio esters 15 .