Search results for "Medicinal Chemistry"

Spektrale eigenschaften und tautomerie aromatischer thiacyclole. Reaktionen mit aktivierten säureamiden. XV

1970

ISomerization of xylene: MINDO/3 study of the cyclization of benzenium cation into bicyclo[3.1.0]hexenyl cation

1989

Abstract A MINDO/3 study of thermal electrocyclic closing of the benzenium cation to form a bicyclo[3.1.0]hexenyl cation is presented. The calculated mechanism discusses the possibility of cyclization of xylenium cations on a silica catalyst or in superacid media. The structure and energy of the transition state, the enthalpies of isomerization and barriers of activation were calculated for the following processes: isomerization of 2,6-dimethylbenzenium cation into 2,6-dimethylbicyclo[3.1.0]hexenyl cation, isomerization of 2,4-dimethylbenzenium cation into 2,4-dimethylbicyclo[3.1.0]-hexenyl cation, and isomerization of benzenium cation into bicyclo[3.1.0]-hexenyl cation. Equilibrium and kin…

THE KINETICS AND MECHANISM OF THE REACTION OF ONIUM CYCLOPENTADIENYLIDES WITH TETRAHALO-p-BENZOQUINONES

1989

Abstract The reaction of triphenylphosphonium cyclopentadienylide (1) with halogen-substituted p-benzoquinones (4) is shown to give a new class of dipolar (zwitterionic) dyes (5) containing phosphorus. The general structure of these molecules has been investigated by a combination of mass spectrometry and multinuclear (7H, 13C and 31P) nmr using the specialist techniques of DEFT spectroscopy, homonuclear (COSY) and heteronuclear 2-D nmr. In addition, stopped-flow (uv/visible) techniques have been used to study the kinetics of the reactions and hence demonstrate that the rate-limiting step is nucleophilic addition of the ylid nucleophile to the quinone, followed by a rapid loss of halide ion…

Über die Synthese von o-Acylamino-β-dimethylamino-propiophenonen 2. Mitt.: Aminomethylierung von o-Carbäthoxyamino- und o-Nitro-acetophenon1)

1970

Die bei der Mannich-Reaktion mit o-Carbathoxyamino- und o-Nitro-acetophenon zu Acrylophenonderivaten fuhrende Sekundarreaktion zwischen den Aminomethylierungsprodukten und Formaldehyd konnte auf folgende Weise nahezu vollstandig vermieden werden: durch Verhindern des Zerfalls von intermediar entstehendem Dimethylaminomethylol in seine Komponenten wird die Bildung des Carbonium-Imonium-Kations derart beschleunigt, das fur die Nebenreaktion erforderlicher freier Formaldehyd rasch aus dem Reaktionsmedium verschwindet. — Die Synthese von o-Carbathoxyamino-, o-Nitro- und o-Amino-β-dimethylamino-propiophenon sowie seines Formyl- und Acetylderivates wird beschrieben. Synthesis of o-Acylamino-β-dim…

Inhibitoren der Korrosion (8) Über die Abhängigkeit der Korrosionsinhibierung des Eisens in Salzsäure von der Struktur quartärer Phosphoniumsalze

1971

Bei quartaren Phosphoniumsalzen be-steht zwischen der Inhibitorwirkung im sauren Medium unter Auschlus von Luft und den polarographisch ermittelten Re-duktionspotentialen keine direkte Bezie-hung. Die sterischen Faktoren der nach Aufnahme von zwei Elektronen entste-henden und an der Eisenoberflache fixierten Fragmente sind offenbar fur die Inhibitorwirkung hauptsachlich ver-antwortlich. Bisphoniumsalze mit gesattigten oder ungesattigten Brucken sind unter den oben genannten Bedingungen hervor-ragende Inhibitoren. Am wirksamsten sind Bisphosphoniumsalze mit Ketten von 4 bis 10 Methylengruppen zwischen den Phosphoniumzentren. Der starre p-Phenylenrest ist als Verknupfungs-prinzip weniger geei…

Investigations on organoantimony compounds

1977

Abstract Trichlorodiorganoantimony(V) compounds, R2SbCl3, in which the antimony atom is part of a heterocyclic ring have been synthesized. They have been converted into the corresponding tetramethylammonium tetrachlorodiorganoantimonates, [R2SbCl4]− [Me4N]+, which are hexacoordinate diorganoantimony(V) species in which the antimony-carbon bonds are forced into a cis-position. 5,5,5-Trichlorodibenzostibole, 10,10,10-trichlorophenoxantimonin, 5,5,5-trichloro-5,10-dihydrodibenz[b, e]antimonin and 5,5,5-trichloro-10,11-dihydro-5H-dibenzo[b, f]stibepin have been prepared by chlorination of the corresponding heterocyclic chlorodiarylstibines. Heterocyclic trichlorodialkylantimony(V) compounds hav…

New bronchodilators selected by molecular topology.

1998

Molecular topology has been applied to find new lead compounds with bronchodilator activity. Among the selected compounds stands out 3-(1H-tetrazol-5yl)-9H-thioxanthene-9 -one-10,10-dioxide, anthrarobin, 9-oxo-9H-thioxantene-3-carboxylic-10,10-dioxide acid, acenocoumarol and griseofulvin, with a percentage of relaxation, at 0.1 mM, of 91, 92, 85, 69, and 74%, respectively. Theophylline shows a correspondent value of 77% (Emax = 100% at 1 mM).

Crystal structure of bis(cyclohexylammonium) diphenyldioxalatostannate(IV)

2015

In the title salt, (CyNH3)2[Sn(Ph2)(C2O4)2] (Cy is cyclo­hexyl and Ph is phen­yl), the SnPh2 moiety is chelated by two oxalate anions, leading to a cis arrangement within the distorted octa­hedral coordination sphere of the SnIV atom.

N-Methyl-4-(4-nitrophenyl)-N-nitroso-1,3-thiazol-2-amine

2017

The title compound, C10H8N4O3S, is almost planar [dihedral angle between the rings = 2.2 (2)°; r.m.s. deviation for the non-H atoms = 0.050 Å]. In the crystal, C—H...O and C—H...N hydrogen bonds link the molecules into (10-2) layers.

Rearrangement products of 3-methanesulfonyl-N-methyl-N-nitroaniline.

2003

Two isomeric products (C 8 H 10 N 2 O 4 S) of the rearrangement of 3-methanesulfonyl-N-methyl-N-nitroaniline have been investigated, viz. 3-methanesulfonyl-N-methyl-2-nitroaniline, which was the main product of the rearrangement, and 5-methanesulfonyl-N-methyl-2-nitroaniline. In both molecules, the aromatic rings are appreciably deformed towards ortho-quinonoidal geometry by electronic and steric interactions. The crystal structure is stabilized, in both cases, by weak C-H...O hydrogen bonds.