Search results for "Selectivity"
showing 10 items of 1148 documents
Palladium-Catalyzed Alkoxy- and Aminocarbonylation of α-Halomethyl Oxime Ethers: Synthesis of 1,3-Alkoxyimino Esters and 1,3-Alkoxyimino Amides
2014
The three component reactions of α-bromomethyl oxime ethers, carbon monoxide, and alcohols or aromatic amines give imino esters and amides, respectively.
Catalytic performance of CoAlZn and NiAlZn mixed oxides in hydrogen production by bio-ethanol partial oxidation
2013
CoAlZn and NiAlZn mixed oxides were prepared by sol-gel method and tested in partial oxidation of bio-ethanol (POE). At lower temperatures, CoAlZn showed higher ethanol conversion and higher selectivity to H2 and CO than NiAlZn. At higher temperatures, ethanol conversion on both catalysts reached 100%, while selectivity (S) to H2 and CO became higher on NiAlZn. At 750 C, NiAlZn showed S(H2) of 95%, S(CO) of 90%, while for CoAlZn these values were 90% and 83% respectively. Both catalysts were resistant to coking, but the amount of carbon deposits was still lower on NiAlZn. During 50 h on-stream, ethanol conversion and selectivity to H2 and CO on NiAlZn remained unchanged demonstrating stable…
Human Development from Middle Childhood to Middle Adulthood
2017
This seminal work focuses on human development from middle childhood to middle adulthood, through analysis of the research findings of the groundbreaking Jyvaskyla Longitudinal Study of Personality and Social Development (JYLS). The JYLS project, which began in 1968, has generated extensive publications over many years but this is the first comprehensive summary that presents the conceptual framework, the research design and methodology, and the findings. The study looks at the development over time of issues related to personality, identity, health, anti-social behavior, and well-being and is unparalleled in its duration, intensity, comprehensiveness and psychological richness. The thoroug…
High pressure liquid chromatography resolution of racemic mixtures of chiral tricarbonyl arene chromium(0) and cyclopentadienyl-titanium(IV) complexes
1998
Abstract Enantiomers of chiral tricarbonyl arene chromium(0) and cyclopentadienyl-titanium(IV) complexes have been separated by high pressure liquid chromatography employing a Chiralcel OD (Daicel) column, eluting with hexane/2-propanol mixtures. The capacity factors ( k ) and selectivity factors ( α ) concerning the separation of these compounds have been determined. The resolution of tricarbonyl( η 6 -methyl o -acetylbenzoate)chromium ( IV ), was carried out on semipreparative scale: a comparison of the CD spectra of the enantiomers IVa and IVb with that reported in the literature for a similar complex allowed to establish the absolute configuration [( 1R )] for the most retained enantiom…
A PLE-based resolution of cocaine, pseudococaine, and 6- and 7-methoxylated cocaine analogues
1996
Abstract The enzymatic hydrolysis of racemic cocaine and cocaine analogues using pig liver esterase (PLE) is shown to afford a practical means for achieving their chemical resolution. This reaction was found to proceed not only with good enantioselectivity, but with an interesting chemoselectivity as well.
Selective Inhibition of STAT3 with Respect to STAT1: Insights from Molecular Dynamics and Ensemble Docking Simulations
2016
STAT3 protein, which is known to be involved in cancer development, is a promising target for anticancer therapy. Successful inhibitors of STAT3 should not affect an activity of closely related protein STAT1, which makes their development challenging. The mechanisms of selectivity of several existing STAT3 inhibitors are not clear. In this work, we studied molecular mechanisms of selectivity of 13 experimentally tested STAT3 inhibitors by means of extensive molecular dynamics and ensemble docking simulations. It is shown that all studied inhibitors bind to the large part of the protein surface in an unspecific statistical manner. The binding to the dimerization interface of the SH2 domain, …
Synthesis, Absolute Configuration, and Bacterial Mutagenicity of the 8 Stereoisomeric Vicinal Diol Epoxides at the Terminal Benzo Ring of Carcinogeni…
2011
The synthesis of the 8 possible stereoisomeric diol epoxides (DEs) at the terminal benzo ring of carcinogenic dibenz[a,h]anthracene (DBA) is reported. trans-3,4-Dihydroxy-3,4-dihydro-DBA (1) afforded the 4 bay region DEs: the enantiomeric pairs of the anti diastereomers (+)-3/(-)-3 and of the syn diastereomers (-)-4/(+)-4, respectively. trans-1,2-Dihydroxy-1,2-dihydro-DBA (2) served as precursor of the 4 reverse DEs: the enantiomeric pairs of the anti diastereomers (+)-5/(-)-5 and of the syn diastereomers (-)-6/(+)-6, respectively. The transformation of the olefinic double bond in the enantiomeric trans-dihydrodiols to epoxides was achieved by either (i) oxidation with m-chloroperoxybenzoic…
Regio- and stereoselective synthesis of spiro-heterocycles bearing the pyrazole scaffold via [3+2] cycloaddition reaction
2022
Abstract Herein we reported the utility of one-pot multicomponent based [3+2] cycloaddition reaction transformation to prepare a new two hybrids of spirooxindoles engrafted with pyrazole skeleton. Upon treatment of the electron-deficient olefins based pyrazole motif with in situ the generated azomethine ylides (AY) of sarcosine with the 6-chloro-isatin afforded spiroadducts. To enlighten the regio- and diastereo-selectivity of these spiroheterocycles, single crystal X-ray diffraction analysis was presented. Using Hirshfeld calculations, many short distance contacts such as O…H, Cl…H, N…H, H…C, C…C and Cl…S have a great impact on the molecular packing and the crystal stability of 8a and 8b. …
Heteroaromatic Inhibitors of the Astacin Proteinases Meprin α, Meprin β and Ovastacin Discovered by a Scaffold-Hopping Approach.
2020
Abstract Astacin metalloproteinases, in particular meprins α and β, as well as ovastacin, are emerging drug targets. Drug‐discovery efforts have led to the development of the first potent and selective inhibitors in the last few years. However, the most recent compounds are based on a highly flexible tertiary amine scaffold that could cause metabolic liabilities or decreased potency due to the entropic penalty upon binding to the target. Thus, the aim of this study was to discover novel conformationally constrained scaffolds as starting points for further inhibitor optimization. Shifting from flexible tertiary amines to rigid heteroaromatic cores resulted in a boost in inhibitory activity. …
Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols
2021
A library of pinane-based 2-amino-1,3-diols was synthesised in a stereoselective manner. Isopinocarveol prepared from (−)-α-pinene was converted into condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray spectroscopic techniques. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from the commercially available (1R)-(−)-myrtenol (10). The reduction or alkaline hydrolysis of the oxazolidines, followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent a reg…