Search results for "Medicinal"

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]

The identification of vicinally substituted cyclohexane isomers in their mixtures by 1H and 13C NMR spectroscopy.

2000

The radical addition reactions of organobromine compounds, XBr (X = CH2COOMe, PhCH2, CHBr2 and CCl3) with cyclohexene afforded mixtures of cis/trans isomer pairs of 1-X-2-Br-cyclohexanes. In addition to benzyl benzoyloxy derivatives are formed also, when benzoyl peroxide is used as an initiator. Owing to the great difficulties in separating these cis/trans isomer pairs, they are identified directly in their mixtures by NMR spectroscopy. In addition to one-dimensional (ID) 1H, proton decoupled 13C and DEPT-135, also two-dimensional (2D) 13C-13C INADEQUATE as well as 1H-13C HMQC experiments have been used in assigning the signals of each compound in their mixtures. The identification of each …

Asymmetric Addition and Cycloaddition Reactions with Ylidene‐Five‐Membered Heterocycles

2021

Five-membered heterocycles bearing an exocyclic double bond have been successfully used as substrates in asymmetric addition and cycloaddition reactions. Ylidene-heterocycles are attractive substrates due to their high functionalization and the presence of an electrophilic conjugated exocyclic double bound that can participate in nucleophilic addition reactions as well as cycloaddition reactions, which may be triggered by the formation of aromatic intermediates or products in many cases. During the last decades, catalytic methodologies have been developed using ylidene-heterocycles as substrates in order to synthesize useful optically active heterocyclic derivatives. 4-Ylidene-pyrazol-5-one…

Enantioselective Addition of Dimethylzinc to Aldehydes Catalyzed by N-Substituted Mandelamide-Ti(IV) Complexes.

2005

Abstract Amides derived from ( S )-(+)-mandelic acid in the presence of titanium isopropoxide catalyze the enantioselective addition of dimethylzinc to aromatic aldehydes with good yields and ee up to 90%.

2014

Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta react…