Search results for "Medicinal chemistry"

Zur protonenkatalysierten Xanthenylierung von Tryptamin, Nω-Acetyltryptamin und Gramin: Ein Beitrag zur Konstitutionsaufklärung in der Indol-Analytik

1988

Aminosäureester als chirale Hilfsgruppen in Lewis-Säure-katalysierten Diels-Alder-Reaktionen

1990

Amino Acid Esters as Chiral Auxiliaries in Lewis Acid Catalyzed Diels-Alder Reactions Cyclopentadiene, cyclohexadiene and alkyl-substituted butadienes react with N-acryloyl-, N-crotonoyl- and N-(4-nitro-cinnamoyl)-(S)-proline benzyl and allyl ester in the presence of Lewis acids to give the cycloadducts in high yields and with stereoselectivities of up to 97:3 for the endo isomers. The sense of the asymmetric induction in these reactions can be directed by the use of differently coordinating catalysts (e.g. TiCl4: (2R):(2S) = 96:4; EtAlCl2: (2R):(2S) = 10:90 at 0°C). In the TiCl4-catalyzed reactions with the fumaric acid derivatives the ratio of the diastereomers reaches values of up to 112…

Phase equilibria in the systems isobutyl alcohol+N,N-dimethylformamide, isobutyl acetate+N,N-dimethylformamide and isobutyl alcohol+isobutyl acetate+…

2005

Abstract Consistent vapor–liquid equilibria (VLE) were determined for the ternary system isobutyl alcohol (IBA) + isobutyl acetate (IBAc) + N,N-dimethylformamide (DMF) and two constituent binary systems at 101.3 kPa. The IBA + DMF system exhibits negative deviation from ideal behaviour and IBAc + DMF system deviates positively from ideal behaviour. The activity coefficients of the solutions were correlated with its composition by the Wilson, NRTL and UNIQUAC models. The ternary system is well predicted from binary interaction parameters.

Isobaric Vapor−Liquid Equilibria for Binary and Ternary Mixtures of Dipropyl Ether, 1-Propyl Alcohol, and Butyl Propionate

2006

Consistent vapor−liquid equilibrium (VLE) data at 101.3 kPa have been determined for the ternary system dipropyl ether + 1-propyl alcohol + butyl propionate and two constituent binary systems:  dipropyl ether + butyl propionate and 1-propyl alcohol + butyl propionate. The dipropyl ether + butyl propionate system exhibits ideal behavior, and the 1-propyl alcohol + butyl propionate system shows positive deviations from Raoult's law. No additional azeotropes are present. The activity coefficients of the solutions were correlated with its composition by the Wilson, NRTL, and UNIQUAC models. The ternary system is well-predicted from binary interaction parameters. Butyl propionate breaks the dipr…

Isobaric vapor–liquid equilibria for the binary systems isobutyl alcohol+isobutyl acetate and tert-butyl alcohol+tert-butyl acetate at 20 and 101.3kPa

2005

Abstract New consistent vapor–liquid equilibrium data for the binary systems isobutyl alcohol (IBA) + isobutyl acetate (IBAc) and tert-butyl alcohol (TBA) + tert-butyl acetate (TBAc) are reported at 20 and 101.3 kPa. The IBA + IBAc system, which deviates positively from ideal behavior, can be described as symmetric solution and presents azeotrope at both pressures. The TBA + TBAc system shows positive deviations from ideal behavior and presents azeotrope only at 20 kPa. The activity coefficients and boiling points of the solutions were correlated with their composition by the Wilson, UNIQUAC, NRTL and Wisniak–Tamir equations.

Analgetische Wirkstoffe, 11. Mitt. Diacylderivate des Butyroguanamins

1986

Derivatisation of Pyrogallarenes

2005

Derivatisation of upper-rim hydroxy groups of pyrogallarenes produced completely acylated and tosylated pyrogallarene derivatives. Mesitylation of pyrogallarene, however, resulted in a regioselective derivatisation of hydroxy groups, i.e. eight OH groups out of 12 were mesitylated. Crystal structures of the synthesised pyrogallarene derivatives indicate that completely substituted pyrogallarenes exist in a distorted crown conformation despite of the lack of stabilising intramolecular hydrogen bonds. In contrast, the partially substituted pyrogallarene adopts a boat conformation and has an open cavity for the inclusion of small guest molecules. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinh…

Die Synthese vono-Acylamino-β-dimethylamino-propiophenonen. 4. Mitt.: Synthese der primären Mannich-Basen

1972

Das durch Umsetzung von 2-Acetamino-β-dimethylamino-propiophenon (IVb) mit Dibenzylamin darstellbare 2-Acetamino-β-dibenzylamino-propiophenon (XXVII) kann hydrogenolytisch mit tels Palladium-Aktivkohle in die entsprechende, nur am aromatischen Stickstoff acetylierte primare Mannich-Base ubergefuhrt werden. In analoger Weise sind auch in 5-Stellung substituierte Derivate des 2-Acetamino-β-amino-propiophenons (XXVIII) zuganglich. Synthesis of 2-Acylamino-β-amino-propiophenones 2-Acetamino-β-dibenzylamino-propiophenone (XXVII) and its derivatives, substituted in 5-position, can be synthetized by reaction of 2-acetamino-β-dimethylamino-propiophenone (IVb) with dibenzylamine. By hydrogenolysis i…

Preparation of 5-methyl-2-sulfanyl-7h-1,3,4-thiadiazolo[3,2-a]-pyrimidin-7-ones

2007

7H-1,3,4-Thiadiazolo[3,2-a]pyrimidin-7-ones can be prepared by the acylation of 5-amino-1,3,4-thiadiazoles with diketene and subsequent ring closure (dehydration). Whereas arylthio substituents (SC6H5) can be introduced in 2-position by the replacement of Br, alkylthio groups (SC2H5) have to be already presentin the starting 5-amino-1,3,4-thiadiazole. The ambident nucleophile 2-thiazolidinethione reacts in the Br substitution reaction on the N atom.

First Protection of a Wide-Rim Tetraamino Calix[4]arene in Opposite Positions

2007

The importance of tetraamino calix[4]arenes as starting materials is distinctly increased by the first versatile protective group for opposite amino functions. Reaction with trityl chloride leads to the 1,3-dialkylated derivative easily isolated in 34% yield; after a first acylation of the remaining amino groups, the trityl residues can be removed by TFA to introduce a second acyl group. [reaction: see text]