Search results for "Activity"
showing 10 items of 7178 documents
Struktur-Wirkungs-Beziehungen bei Histaminanaloga, 21. Mitt. Synthese und Wirkung Nα-substituierter Histamine
1980
Es wurden Nα-substituierte Histamine dargestellt und auf ihre agonistische Wirkung an Histamin H1- und H2-Rezeptoren untersucht. Structure-Activity Relationships of Histamine Analogues, XXI: Synthesis and Pharmacology of Nα-Substituted Histamines Nα-Substituted histamines were synthesized and investigated with regard to their agonistic activity at histamine H1 and H2 receptors.
ChemInform Abstract: Heterocycles from α-Aminonitriles
2014
Owing to their various modes of reactivity, α-aminonitriles represent versatile building blocks for the construction of a wide range of nitrogen heterocycles. The present Concept article focuses on synthetic methodologies using their bifunctional nature which is the basis of their reactivity as α-amino carbanions and as iminium ions. Reactions exclusively taking place on either the amine or on the nitrile moiety will not be considered.
Azomethin-imine durch Umsetzung von Diphenylketen mit Azodicarbonsäureestern
1981
Die Umsetzung von Diphenylketen mit Azodicarbonsaureester fuhrt zu den Azomethin-iminen 4, die 1,3-dipolare Reaktivitat zeigen: Addition von Diphenylketen liefert das Addukt 8, von Phenylisocyanat ergibt 7 und Dimerisierung fuhrt zu 5. Azomethine Imines by Reaction of Diphenylketene with Azodicarboxylates1) The reaction of diphenylketene with azodicarboxylates yields azomethine imines 4 which show 1,3-dipolaric reactivity: addition of diphenylketene yields the 2:1-adduct 8, addition of phenyl-isocyanate produces 7, and dimerization leads to 5.
Synthesis, Characterisation, and Reactivity of 1-(1-Methylimidazol-2-yl)ethenes
1990
Abstract Thermally labile 1-(1-methylimidazol-2-yl)-ethenes, synthesised using the Wittig reaction, have been characterised as stable picrate or N-phenacyl salts. The free bases can be regenerated from the picrates on treatment with triethylamine and their reactivity with dienophiles is described.
Highly Enantio- and Diastereoselective Inverse Electron Demand Hetero-Diels-Alder Reaction using 2-Alkenoylpyridine N-Oxides as Oxo-Heterodienes
2008
A general catalytic inverse electron demand hetero-Diels Alder reaction for 2-alkenoylpyridine N-oxides is presented. 2-Alkenoylpyridine N-oxides react very efficiently with alkenes in the presence of bisoxazolidine-copper(II) [BOX-Cu(II)] complexes to give chiral dihydropyrans bearing a pyridine ring at the 6-position with very high yields and excellent diastereo- and enantioselectivity. These heterodienes exhibited higher reactivity and enantioselectivity than the corresponding non-oxidized 2-alkenoylpyridines.
ChemInform Abstract: Fluorous TBAF: A Convenient and Selective Reagent for Fluoride-Mediated Deprotections.
2010
A fluorous analogue of TBAF has been developed for its use in the clean removal of silicon-derived protecting groups. Purification of the crude mixtures by fluorous solid-phase extractions allowed alcohols, amines, and carboxylic acids to be obtained in high purity, with no need of chromatographic separations. The moderate reactivity of fluorous TBAF was exploited in selective deprotections of several bifunctional molecules.
Synthesis and Reactivity of New β-Enamino Acid Derivatives: A Simple and General Approach to β-Enamino Esters and Thioesters
1998
A new strategy has been developed for the synthesis of several β-enamino acid derivatives. N,N‘-Carbonyldiimidazole has been used as C-acylating agent of methyl ketimines, providing a direct and simple route to new β-enamino carbonyl imidazole derivatives 2. These derivatives 2 were cleanly and efficiently transformed into β-enamino esters 4 (X = O) and thioesters 4 (X = S) by reaction with a great variety of alcohols and thiols, including tertiary ones. Alternative and complementary routes to compounds 4 were also investigated. In addition, β-keto esters 6 have been obtained by mild acid hydrolysis of β-enamino esters 4.
H2-Antihistaminika, 35. Mitt. Synthese und H2-antagonistische Wirkung imidazolylmethylthioalkyl-substituierter 1,2,4-Triazole
1987
Es wurden mono-, di- und trisubstituierte 1,2,4-Triazolderivate dargestellt und auf Histamin-H2-antagonistische Aktivitat untersucht. H2-Antihistaminics, XXXV: Synthesis and H2-Antagonistic Activity of Imidazolylmethylthioalkyl-Substituted 1,2,4-Triazoles Mono-, di- and trisubstituted 1,2,4-triazoles were prepared and tested for histamine H2-antagonistic activity.
ChemInform Abstract: Two-Carbon Bridge Substituted Cocaines: Enantioselective Synthesis, Attribution of the Absolute Configuration, and Biological Ac…
2010
In an effort to learn more about the general structure-activity relationships of cocaine with the aim to elucidate those structural features that might confer antagonistic properties to such analogues, we describe herein our synthetic efforts to prepare two-carbon bridge functionalized (methoxylated and hydroxylated) analogues. Our approach makes use of a modification of the classical Willstatter synthesis of cocaine: Mannich type cyclization of acetonedicarboxylic acid monomethyl ester with methylamine hydrochloride and 2-methoxysuccindialdehyde in a citrate buffer solution afforded the 6- and 7-substituted 2-carbomethoxy-3-tropinones 3a,b and 4a,b in approximate yields of 64%. Reduction o…
Photochemical reactivity of 6α-hydroxy, 7-keto neoclerodane diterpenoids
2006
Abstract The photochemical reactivity, in methanol at λ = 254 nm, of two 6α-hydroxy-7-keto neoclerodane, isoeriocephalin ( 1 ) and teucrolivin B ( 2 ) was evaluated. From the first compound, two new products were obtained: the 6β-hydroxy epimer ( 3 ) and the ɛ-lactone ( 4 ). The second one yielded exclusively the new spiro γ-lactone ( 5 ). The formation of these new products can be explained by the well-known radical mechanism Norrish type I.