Search results for "Two step"

Synthesis of 2-Aminothiazole Derivatives in Easy Two-Step, One-Pot Reaction

2018

Efficient two-step synthesis of face-to-face meso-substituted bis(corrole) dyads

2008

The synthesis of face-to-face meso-substituted bis(corrole) systems was revisited. By using a new synthetic pathway, the reaction was generalized to any type of linker and the yield was considerably increased. The dyads were obtained in yields up to 20 % from a dialdehyde linker and dipyrromethane in a one-step reaction. The best reaction conditions required a decreased amount of TFA catalyst (1.4 equiv.) and a large excess of dipyrromethane (up to 8 equiv). Under these conditions, four bis(corrole)s linked by 2,2′-diphenyl ether, 9,9-dimethylxanthene, anthracene, and dibenzofuran spacers were synthesized.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Two-step radiosynthesis of [18F]FE-β-CIT and [18F]PR04.MZ

2013

The cocaine-derived dopamine reuptake inhibitors FE-β-CIT (8-(2-fluoroethyl)-3-(4-iodophenyl)-8-azabicyclo[3.2.1]octane-2-carboxylic acid methyl ester) (1) and PR04.MZ(8-(4-fluorobut-2-ynyl)-3-p-tolyl-8-azabicyclo[3.2.1]octane-2-carboxylic acid methyl ester) (2) were labelled with (18)F-fluorine using a two-step route. 2-[(18)F]Fluoroethyltosylate and 4-[(18)F]fluorobut-2-yne-1-yl tosylate were used as labelling reagents, respectively. Radiochemically pure (>98%) [(18)F]FE-β-CIT and [(18)F]PRD04.MZ (32-86 GBq/µmol) were obtained after a synthesis time of 100 min in about 25% non-decay-corrected overall yield.

Modelling of two step high spin⇌low spin transitions using the cluster variation method

1998

Abstract A thermodynamic description of high spin (HS)⇌low spin (LS) transition curves beyond the Bragg–Williams approximation is given using the Kikuchi cluster variation method (CVM). Transition curves of unusual behaviour (i.e. two step transition) are reproduced by short range interaction energies which are present in addition to long range elastic interaction between the spin changing molecules. The correlations in the distribution of the spin changing centers can be expressed analytically. They give rise to a reduced mixing entropy which was found experimentally in compounds with two step transitions.

Acetaldehyde and salsolinol in ethanol’s two-step mechanism of action: An overview

2018

In the last years, numerous studies have supported the idea that, at least in part, motivational and neuropharmacological effects of ethanol are mediated by its first brain-derived metabolite, acetaldehyde, and its bioderivate salsolinol. This review aims at gathering and shaping as a whole the evidence on their role in the mechanism of action of ethanol. Acetaldehyde and salsolinol interact with the reward brain system and are involved as primum movens of motivational and addictive behaviour that can be especially relevant to ethanol use disorders. Understanding the neurobiology of acetaldehyde and salsolinol holds promising potential for the development of novel pharmacological approaches…

Synthesis of No-Carrier-Added 4-[18F]Fluorophenol from 4-Benzyloxyphenyl-(2-thienyl)iodonium Bromide

2011

4-[(18)F]Fluorophenol is a versatile synthon for the synthesis of more complex radiopharmaceuticals bearing a 4-[(18)F]fluorophenoxy moiety. In order to prepare 4-[(18)F]fluorophenol in no-carrier-added (n.c.a.) form only a nucleophilic labelling method starting from [(18)F]fluoride is suitable. In this paper a new, two step radiosynthesis starting from 4-benzyloxyphenyl-(2-thienyl)iodonium bromide and [(18)F]fluoride with subsequent deprotection is described, yielding n.c.a. [(18)F]fluorophenol in 34 to 36% radiochemical yield.

Health care spending structures in Poland, Latvia, Lithuania and Estonia over the years as compared to other EU countries

2018

Abstract After joining the European Union in 2004, the post-communist countries have dramatically changed their structure of expenditure for medical services. The cause of this is legislative and ownership changes in the new economy. The study analyzed the expenditure on medical services in the European Union with a special focus on Poland, Latvia, Lithuania and Estonia. The European Union countries were divided into clusters using different methods, that is, Ward’s, Two Step and Centroid Clustering. In the paper, the structure and changes in health expenses were presented according to the types of expenditures over the years 2004-2015. Countries were assigned to clusters based on three var…

Two-Step Route to Indoles and Analogues from Haloarenes: A Variation on the Fischer Indole Synthesis

2012

In a new variation on the Fischer indole synthesis, readily available haloarenes are converted into a wide range of indoles in just two steps by halogen-magnesium exchange and quenching with di-tert-butyl azodicarboxylate, followed by reaction with aldehydes or ketones under acidic conditions. The protocol, which is readily extended to the preparation of indole isosteres, 4- and 6-azaindoles and thienopyrroles, obviates the need to prepare potentially toxic aryl hydrazines, simultaneously avoiding undesirable anilines such as naphthylamines.

Cautionary Note on the Two-Step Transformation to Normality

2019

ABSTRACT Templeton and Burney (2017) proposed a two-step normality transformation as a remedy for non-normally distributed data, which are commonly found in AIS research. We argue that, rather than transforming the data toward normality, researchers should first seek to analyze and understand the sources of non-normality. Using simulated datasets, we demonstrate three sources of non-normality and their consequences for regression estimation. We then demonstrate that the two-step transformation cannot solve any of these problems and that each source of non-normality can be handled with alternative, existing techniques. We further present two empirical examples to demonstrate these issues wit…

Der 2‐(Methylthio)äthoxycarbonyl‐Rest als Zweistufen‐Schutzgruppe für die Aminofunktion in Aminosäuren und Peptiden

1976

Die 2-(Methylthio)athoxycarbonyl(Mtc)-Gruppe wird als neue Amino-Schutzgruppe fur Aminosauren und Peptide beschrieben. Zu ihrer Einfuhrung eignen sich sowohl das Mtc-p-Nitrophenolat als auch das Mtc-Phenolat. Die Mtc-Schutzgruppe ist in Masig alkalischem oder saurem Medium bestandig. Durch zwei unterschiedliche und einfache Reaktionen kann die unempfindliche Mtc-Gruppe in gegenuber Basen sehr empfindliche Schutzgruppen umgewandelt werden und wird deshalb als Zweistufen-Schutzgruppe bezeichnet. Die Methylierung zur 2-(Dimethylsulfonio)-athoxycarbonyl-Schutzgruppe verlauft nicht immer befriedigend, erbringt jedoch oft N-geschutzte Verbindungen, die sehr gut in Wasser loslich sind. Nahezu quan…