This Mini-Review highlights the most effective protocols for metal-free direct synthesis of imidazo1,2-apyridines, crucial target products and key intermediates, developed in the past decade. The ...emphases is given on the ecological impact of the methods and on the mechanistic aspects as well. The procedures efficiently applied in the preparation of important drugs and promising drug candidates are also underlined.
Synthesis of Chiral Cyclopentenones Simeonov, Svilen P; Nunes, João P M; Guerra, Krassimira ...
Chemical reviews,
05/2016, Volume:
116, Issue:
10
Journal Article
Peer reviewed
The cyclopentenone unit is a very powerful synthon for the synthesis of a variety of bioactive target molecules. This is due to the broad diversity of chemical modifications available for the enone ...structural motif. In particular, chiral cyclopentenones are important precursors in the asymmetric synthesis of target chiral molecules. This Review provides an overview of reported methods for enantioselective and asymmetric syntheses of cyclopentenones, including chemical and enzymatic resolution, asymmetric synthesis via Pauson-Khand reaction, Nazarov cyclization and organocatalyzed reactions, asymmetric functionalization of the existing cyclopentenone unit, and functionalization of chiral building blocks.
The main objective of the present review is to provide an overview on the synergistic solvent extraction of lanthanoids, in particularly on the use of β-diketone/calixarene
i.e.
acidic/neutral ...mixture, as well as the analysis of data hitherto reported in this scientific topic. Based on the previously presented results, the extraction efficiency has been careful examined and discussed mainly in terms of the corresponding equilibrium constants among other outlined extraction parameters. Furthermore, the evaluation of the chelating ligand structures and p
K
a
values are emphasized. Major conclusions on the role of calixarene's ligating groups towards the mechanism, the improved extraction enhancement and selectivity are additionally provided. Consequently, it is very important that the obtained remarkable architecture of the formed complexes with very high coordination numbers (10/12) including a few cyclic molecules is in accordance with the well-established principles of coordination 4f-ion chemistry. Finally, a critical analysis of the lanthanoid intra-group selectivity (light/middle, heavy/middle and light/heavy 4f-ion pairs)
versus
the extraction performance of the acidic/neutral combinations and, on the other hand, the nature of the water-immiscible molecular or ionic diluent used have also been carried out and are here presented and critically addressed.
The objective of the review is to provide an overview on the synergistic solvent extraction of lanthanoids: β-diketone/calixarene mixtures.
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