scholarly journals An improved synthesis of adefovir and related analogues

2019 ◽  
Vol 15 ◽  
pp. 801-810 ◽  
Author(s):  
David J Jones ◽  
Eileen M O’Leary ◽  
Timothy P O’Sullivan
Keyword(s):  
Systematic Study ◽  
Antiviral Drug ◽  
Substitution Pattern ◽  
Tetrabutylammonium Salt

An improved synthesis of the antiviral drug adefovir is presented. Problems associated with current routes to adefovir include capricious yields and a reliance on problematic reagents and solvents, such as magnesium tert-butoxide and DMF, to achieve high conversions to the target. A systematic study within our laboratory led to the identification of an iodide reagent which affords higher yields than previous approaches and allows for reactions to be conducted up to 10 g in scale under milder conditions. The use of a novel tetrabutylammonium salt of adenine facilitates alkylations in solvents other than DMF. Additionally, we have investigated how regioselectivity is affected by the substitution pattern of the nucleobase. Finally, this chemistry was successfully applied to the synthesis of several new adefovir analogues, highlighting the versatility of our approach.

Octasolketal-substituted phthalocyanines: synthesis and systematic study of metal effect and substitution pattern on 13C NMR

2009 ◽  
Vol 13 (06) ◽  
pp. 760-768 ◽  
Author(s):  
Yunus Zorlu ◽  
Ilker Un ◽  
Fabienne Dumoulin
Keyword(s):  
Systematic Study ◽  
13C Nmr ◽  
Central Metal ◽  
Substitution Pattern ◽  
Complete Series ◽  
Metal Effect ◽  
C Nmr

A complete series of solketal octasubstituted phthalocyanines have been synthesized, with peripheral (β) or non-peripheral (α) substitution pattern. Their 13 C NMR and UV-vis properties are compared relatively to this substitution pattern or the nature of the central metal ( Ni , Zn or H 2).

scholarly journals Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

2010 ◽  
Vol 6 ◽  
pp. 1229-1245 ◽  
Author(s):  
Jakub Saadi ◽  
Irene Brüdgam ◽  
Hans-Ulrich Reissig
Keyword(s):  
Systematic Study ◽  
Steric Hindrance ◽  
Structural Features ◽  
Samarium Diiodide ◽  
Cyclization Reactions ◽  
Substitution Pattern ◽  
High Importance

A series of γ-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8-endo-trig cyclizations. Efficacy, regioselectivity and stereoselectivity of these reactions via samarium ketyls strongly depend on the substitution pattern of the attacked alkene moiety. The stereoselectivity of the protonation of the intermediate samariumorganyl is also influenced by the structural features of the substrates. This systematic study reveals that steric and electronic factors exhibited by the alkene and ketone subunits are of high importance for the outcome of these cyclization reactions leading to highly substituted benzannulated cyclooctanol derivatives. In exceptional cases, 7-exo-trig cyclizations to cycloheptanol derivatives have been observed. In examples with high steric hindrance the ketyl–aryl coupling can be a competing process.

Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1202-1203
Author(s):  
Gianluigi Botton ◽  
Gilles L'espérance
Keyword(s):  
Statistical Analysis ◽  
Spatial Resolution ◽  
Personal Computer ◽  
Systematic Study ◽  
Present Author ◽  
Chemical Elements ◽  
Detection Limits ◽  
Research Groups ◽  
Quantitative Performance ◽  
Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

A SYSTEMATIC STUDY OF 2s2 2pk - 2s2pk+l - 2pk+2 TRANSITIONS IN MULTIPLY-CHARGED Cl IONS.

1979 ◽  
Vol 40 (C1) ◽  
pp. C1-208-C1-210 ◽  
Author(s):  
J. P. Forester ◽  
D. J. Pegg ◽  
P. M. Griffin ◽  
G. D. Alton ◽  
S. B. Elston ◽  
...  
Keyword(s):  
Systematic Study ◽  
Multiply Charged

The solubility of calcium carbonate  in green liquor handling systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (10) ◽  
pp. 595-602
Author(s):  
ALISHA GIGLIO ◽  
VLADIMIROS G. PAPANGELAKIS ◽  
HONGHI TRAN
Keyword(s):  
Calcium Carbonate ◽  
Systematic Study ◽  
Kraft Pulp ◽  
Thermodynamic Simulation ◽  
Solubility Data ◽  
Pulp Mills ◽  
Persistent Problem ◽  
Green Liquor ◽  
Kraft Pulp Mills ◽  
Salt Systems

The formation of hard calcite (CaCO3) scale in green liquor handling systems is a persistent problem in many kraft pulp mills. CaCO3 precipitates when its concentration in the green liquor exceeds its solubility. While the solubility of CaCO3 in water is well known, it is not so in the highly alkaline green liquor environment. A systematic study was conducted to determine the solubility of CaCO3 in green liquor as a function of temperature, total titratable alkali (TTA), causticity, and sulfidity. The results show that the solubility increases with increased temperature, increased TTA, decreased causticity, and decreased sulfidity. The new solubility data was incorporated into OLI (a thermodynamic simulation program for aqueous salt systems) to generate a series of CaCO3 solubility curves for various green liquor conditions. The results help explain how calcite scale forms in green liquor handling systems.

Hopscotch Modernism: On Everyday Life and the Blurring of Art and Social Science

2006 ◽  
Vol 2 (1) ◽  
pp. 70-79 ◽  
Author(s):  
Ben Highmore
Keyword(s):  
Twentieth Century ◽  
Social Science ◽  
Everyday Life ◽  
Systematic Study ◽  
Cultural Practices ◽  
Health Centre ◽  
Small Scale ◽  
Modernist Literature ◽  
The Everyday ◽  
Point Of Departure

From a remarkably innovative point of departure, Ben Highmore (University of Sussex) suggests that modernist literature and art were not the only cultural practices concerned with reclaiming the everyday and imbuing it with significance. At the same time, Roger Caillois was studying the spontaneous interactions involved in games such as hopscotch, while other small scale institutions such as the Pioneer Health Centre in Peckham, London attempted to reconcile systematic study and knowledge with the non-systematic exchanges in games and play. Highmore suggests that such experiments comprise a less-often recognised ‘modernist heritage’, and argues powerfully for their importance within early-twentieth century anthropology and the newly-emerged field of cultural studies.

Sign in / Sign up

Export Citation Format

Share Document