Search results for "HILIC"

Highly diastereoselective additions of organometallic reagents to 1-O-silylated 3,4-Di-O-benzyl-L-erythrulose derivatives

1993

Abstract The diastereoselectivity of the addition of several organometallic reagents to the carbonyl group of the title compounds has been investigated. Some organomagnesium reagents display high diastereoselectivities (90–99%) and the major products are those predicted by the α-chelation model.

Influence of cyclization and acyl substitution on the inotropic effects of adenine nucleotides.

1973

This study was designed to further elucidate relevance and mechanism of the positive inotropic action of cyclic N6-2′-O-dibutyryl-AMP (DB-c-AMP). For this purpose the effects of cyclic N6-monobutyryl-AMP (N6-MB-c-AMP), noncyclic N6-2′-O-3′-O-tributyryl-5′-AMP (TB-AMP), c-AMP, adenosine and various adenine nucleotides (ATP, ADP, AMP) on myocardial contractile force (CF) were investigated and compared to that of DB-c-AMP. The experiments were performed on isolated, electrically driven (frequency 2 Hz) rat left auricles, i.e. on a preparation in which DB-c-AMP consistently produced positive inotropic effects. The following results were obtained: From the failure of non-cyclic TB-AMP to increas…

Effect of ionization and the nature of the mobile phase in quantitative structure-retention relationship studies.

2005

Abstract The octanol–water distribution constant, commonly called partition coefficient, Po/w, is a parameter often retained as a measure of the hydrophobicity of a molecule. log Po/w, for a given molecule, can be conveniently evaluated constructing correlation lines between standard retention factor logarithms (log k) in reversed-phase liquid chromatography (RPLC) and standard log Po/w values. Many compounds of pharmaceutical interest can be quite hydrophobic and have, simultaneously, basic nitrogen atoms or acidic sulfur containing groups in their structure. This renders them ionizable. The hydrophobicity of the molecular drug form (Po/w value) is completely different from its ionic form …

Modeling of Retention in Reversed Phase Liquid Chromatography

2015

Bioadhesive Matrix Tablets Loaded with Lipophilic Nanoparticles as Vehicles for Drugs for Periodontitis Treatment: Development and Characterization

2019

Periodontitis treatment is usually focused on the reduction or eradication of periodontal pathogens using antibiotics against anaerobic bacteria, such as metronidazole (MTR). Moreover, recently the correlation between periodontal diseases and overexpression of reactive oxygen species (ROS) led to the introduction of antioxidant biomolecules in therapy. In this work, bioadhesive buccal tablets, consisting of a hydrophilic matrix loaded with metronidazole and lipophilic nanoparticles as a vehicle of curcumin, were developed. Curcumin (CUR)-loaded nanostructured lipid carriers (NLC) were prepared using glycyrrhetic acid, hexadecanol, isopropyl palmitate and Tween&reg

Ecthyma- und Keratoakanthom-�hnliche eosinophile Granulome der Haut

1967

Mitteilung einer Beobachtung rezidivierender Ecthyma-und Keratoakanthom-ahnlicher Hautveranderungen bei einem ansonsten gesunden 69 jahrigen Mann, denen histologisch — am Hohepunkt der feingeweblichen Entwicklung — reticulo-histiocytar differenzierte Granulome mit massenhaft Eosinophilen und chronisch-entzundlicher Begleitinfiltration zugrunde lagen. Nach einem Uberblick uber die Entstehung des vieldeutigen Begriffes “eosinophiles Granulom der Haut” wird — gestutzt auf die einschlagige Literatur — unter Berucksichtigung klinischer, histologischer und nosologischer Faktoren eine Einteilung der “eosinophilen Granulome der Haut” in drei Gruppen vorgeschlagen und der beobachtete Fall der zweife…

Synthesis and biological evaluation of dehydroabietic acid derivatives.

2010

A series of C18-oxygenated derivatives of dehydroabietic acid were synthesized from commercial abietic acid and evaluated for their cytotoxic, antimycotic, and antiviral activities.

Fluorinated Heterocyclic Compounds. An Effective Strategy for the Synthesis of Fluorinated Z-Oximes of 3-Perfluoroalkyl-6-phenyl-2H-1,2,4-triazin- 5-…

2005

The reaction of 3-benzoyl-5-perfluoroalkyl-1,2,4-oxadiazoles with hydrazine has been investigated, evidencing the possibility of competitive reaction paths. Nucleophilic addition of the hydrazine to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring opening and ring closure with enlargement, leads with high yield and in very mild experimental conditions to the formation of Z-oximes of 3-perfluoroalkyl-6-phenyl-2H-1,2,4-triazin-5-ones (11a-c) as major products of the reaction. In turn, the hydrazine can attack the electrophilic carbonyl carbon giving 4-perfluoroacylamino-5-phenyl-2H-1,2,3-triazoles (13a-c) through the well-known Boulton-Katritzky rearrangement of the inter…

On the Nucleophilic Reactivity of 4,6-Dichloro-5-nitrobenzofuroxan with Some Aliphatic and Aromatic Amines: Selective nucleophilic substitution

2020

The reaction rates for the nucleophilic aromatic substitution of 4,6-dichloro-5-nitrobenzofuroxan 1 with eight aliphatic amines (characterized by very different basicities/ nucleophilicities) and three anilines have been measured in both methanol and toluene. The obtained rates have been related to the basicity (pKaH in water and Kb in benzene) or nucleophilicity (N Mayr constants) of the tested amines. The whole of the obtained kinetic data has furnished useful information on the high nucleophilic reactivity of benzofuroxan derivatives, which has been related essentially to two factors: the high electron-drawing ability/power of the condensed furoxan ring and the low aromatic character of …

A DFT mechanistic study of the synthesis of trans-Z,Z-[PtIICl(NH3){HN = C(NH2)Me}2]Cl from addition of NH3 to trans-[PtIICl2(N CMe)2]

2020

Abstract The reaction mechanism between trans-[PtIICl2(N CMe)2] and ammonia to give trans-Z,Z-[PtIICl(NH3){HN = C(NH2)Me}2]Cl has been studied at DFT level. Results showed that, in dichloromethane solution at 263.15 K, the chloride substitution by the ammonia on platinum is a process kinetically more favoured than the ammonia nucleophilic addition to the nitrile of about three orders of magnitude, and hence the nucleophilic addition reaction occurs after. Finally, both nucleophilic addition steps are geometrically driven to give products in the E configuration even if the final products were experimentally observed in the Z configuration. For trans-Z,Z-[PtIICl(NH3)(N CMe)2, the isomerizatio…