Search results for "cyclic"

An Insight into Substrate-Dependent Fluorination of some Highly Substituted Alicyclic Scaffolds

2017

The substrate-dependent fluorination of some highly-functionalized cyclopentane derivatives with multiple chiral centers has been investigated. The key steps of the stereocontrolled syntheses are the oxidative cleavage of the ring carbon–carbon double bond of readily available diexo or diendo norbornene β-amino acid derivatives followed by transformation of the resulted dialdehyde stereoisomers by reduction. Finally, substrate-directable chemodifferentiation of different types of hydroxy groups under fluorination procedures gave various densely functionalized alicyclic derivatives or heterocycles.

Expression of Nitric Oxide Synthase I Determines the Strength of Adrenergic Cyclic GMP Response in the Rat Pineal Gland

1997

In the rat pineal gland the adrenergic cGMP response is not static but changes during postnatal development and depends on environmental lighting conditions. Since the adrenergic cGMP transduction is mediated by stimulation of the enzyme nitric oxide synthase I (NOS I), we investigated whether changes in the strength of adrenergic cGMP response coincide with the expression of NOS I. Using immunoblot analysis, we found that the increase in adrenergic cGMP transduction in the second postnatal week coincides with enhanced NOS I expression. Similarly, we observed that changes in the intensity of adrenergic cGMP transduction under different environmental lighting conditions correspond to NOS I e…

Zunehmende Bedeutung von Antidepressiva bei suizidalen und parasuizidalen Intoxikationen

2002

BACKGROUND AND OBJECTIVE: Antidepressant drugs are frequently used in deliberate self-poisoning resulting in a major risk for the patients due to their cardiac and central-nervous toxicity. In the present study the cases of intoxications consulting our Poison Center should be analysed illustrating recent results and trends about self-poisoning with antidepressants. PATIENTS AND METHODS: During the study period from 1995 to 2001 35 394 inquiries concerning deliberate self-poisoning were registered in our Poison Center. The substance used, age and gender of the patient as well as the degree of the observed symptoms were documented. Thereby, antidepressant drugs were grouped in tricyclic antid…

Effect of addition of Lewis/Brönsted acids in the asymmetric aldol condensation catalyzed by trifluoroacetate salts of proline-based dipeptides

2012

Abstract Proline-based dipeptides catalyze aldol condensations with good yield and stereoselectivity after addition of zinc or sodium acetate to the trifluoroacetate peptide. The chirality of the N-terminal proline in the catalyst determines the absolute configuration of the aldol product, but stereoselectivity depends on the configuration of both amino acids, and is higher for the enantiomeric pair R–S, S–R. Regarding the nature of the second component, optimal results in both yield and stereoselectivity are obtained when neutral unbranched primary amino acids are used.

An insight into the synthesis of novel aryl-substituted alicyclic β-amino acid derivatives through substrate-directed palladium-catalysed regio- and …

2015

Novel aryl-substituted alicyclic β-amino acid derivatives were synthesized through substrate-determined palladium-catalysed cross-coupling of aryl iodides with five- or six-membered cycloalkene β-amino esters. The arylations were investigated with different catalysts, solvents, bases and aryl halides, and with some cyclohexene 2-aminocarboxylate isomers. The stereochemistry and the position of the ring olefinic bond of the starting 2-aminocycloalkanecarboxylate influenced the coupling reaction, and predetermined the structure of the arylated product.

Studien zum Vorgang der Wasserstoffübertragung, 47.Elektroreduktion von 1,4-Benzoldicarbonitril, 1,4-Diacetylbenzol und Terephthalaldehyd

1978

Die Elektroreduktion von 1,4-Benzoldicarbonitril in Gegenwart von Essigsaure fuhrt bei einem Stromdurchgang von 4.5 Faraday-aquivalenten/mol in 80proz. Ausbeute zu 4-Amino-methylbenzonitril (1). Bei Anwendung von 6 Faraday-aquivalenten/mol konnen geringe Mengen an 4-Methylbenzonitril (2) nachgewiesen werden. Bei der praparativen Elektroreduktion von 1,4-Diacetylbenzol in Gegenwart unterschiedlicher Mengen an Essigsaure entstehen 4-(1-Hydroxyethyl)acetophenon (3), 1,1′-(1,4-Phenylen)diethanol (4) sowie polymere Pinakole 5 in den in Tabelle 1 angegebenen Mengen. Terephthalaldehyd wird in Gegenwart von Essigsaure zu 4-Hydroxymethylbenzaldehyd (6), Terephthalalkohol (7) und einem polymeren Pina…

Synthesis of 1H-imidazo[3′,4′:4,5]thieno[2,3-b]pyridines. A new ring system

1984

A facile and convenient synthesis of the title compounds is described, using as starting materials the 2-nitro-3-aminothieno[2,3-b]pyridines. Mass spectral data of the above mentioned compounds are briefly discussed.

An Unexpected Three-Component Condensation Leading to Amino- (3-oxo-2,3-dihydro-1H-isoindol-1-ylidene)- acetonitriles

2004

The reaction of 2-carboxybenzaldehyde with primary amines in the presence of cyanide leads to the formation of 2-substituted amino(3-oxo-2,3-dihydro-1H-isoindol-1-ylidene)acetonitriles. These compounds originate from the condensation of 2-carboxybenzaldehyde with the amine and two molecules of hydrogen cyanide and represent a novel class of isoindolinones.

1983

Synthese a partir de l'hexahydro-1,5,5a,6,9,9a benzodioxepinne-2,4. Polymerisation en masse en un produit incolore, cireux (Tg=−11°C)

STUDIES ON BICYCLO[3.3.1]NONANES FOR SYNTHESIS OF CYCLOOCTENES

2002

This paper describes a full conformational and stereochemical study of bicylo[3.3.1]nonanes, obtained from the reaction between cinnamaldehyde and 1-morpholine 1-cyclohexene. NMR data and stereochemistry were unequivocally established and assigned by two-dimensional experiments and single-crystal X-ray analysis. The crystal structure of a minor compound, 4, is reported. Cyclooctenes, which are present in natural products with biological activities, were synthesized from the bicyclononanes via the Wharton fragmentation.