A one-pot synthesis of benzofurans which utilizes a palladium-catalyzed enolate arylation is described. The process demonstrates broad substrate scope and provides differentially substituted benzofurans in moderate to excellent yields. The utility of the method is further demonstrated by the synthesis of the natural product eupomatenoid 6 in three steps.
The asymmetric Pd-catalyzed decarboxylative allylic alkylation of differentially N-protected piperazin-2-ones allows for the synthesis of a variety of highly enantioenriched tertiary piperazine-2-ones. Deprotection and reduction affords the corresponding tertiary piperazines, which can be employed for the synthesis of medicinally important analogs. The introduction of these chiral tertiary piperazines resulted in imatinib analogs that exhibited comparable antiproliferative activity to that of their corresponding imatinib counterparts.
No Strain, No Gain! The first transition metal-catalyzed enantioselective α-alkylation of cyclobutanones is reported. This method employs palladium catalysis and an electron deficient PHOX type ligand to afford all–carbon α-quaternary cyclobutanones in good to excellent yields and enantioselectivities.
Biomolecular systems are commonly exposed to a manifold of forces, often acting between multivalent ligands. To understand these forces, we studied mono-and bivalent model systems of pyridine coordination complexes with Cu 2+ and Zn 2+ in aqueous environment by means of scanning force microscopy based single-molecule force spectroscopy in combination with ab initio DFT calculations. The monovalent interactions show remarkably long rupture lengths of approximately 3 Å that we attribute to a dissociation mechanism involving a hydrogen-bound intermediate state.The bivalent interaction with copper dissociates also via hydrogen-bound intermediates, leading to an even longer rupture length between 5 and 6 Å. Although the bivalent system is thermally more stable, the most probable rupture forces of both systems are similar over the range of measured loading rates. Our results prove that already in small model systems the dissociation mechanism strongly affects the mechanical stability. The presented approach offers the opportunity to study the force-reducing effects also as a function of different backbone properties.
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