Molecular Diversity by Olefin Cross-Metathesis on Solid Support. Generation of Libraries of Biologically Promising β-Lactam Derivatives.

The application of the reagent-based diversification strategy for generation of libraries of biologically promising β-lactam derivatives is described. Key features are the versatility of the linker used and the cross-metathesis functionalization at the cleavage step. From an immobilized primary library, diversity was expanded by applying different cleavage conditions, leading to a series of cholesterol absorption inhibitor analogues together with interesting hybrid compounds through incorporation of a chalcone moiety.

An introductory classroom exercise on protein molecular model visualization and detailed analysis of protein-ligand binding.

A learning module for molecular level analysis of protein structure and ligand/drug interaction through the visualization of X-ray diffraction is presented. Using DeepView as molecular model visualization software, students learn about the general concepts of protein structure. This Biochemistry classroom exercise is designed to be carried out by following the detailed instructions that make software handling straightforward.

The non-metathetic role of Grubbs' carbene complexes: from hydrogen-free reduction of α,β-unsaturated alkenes to solid-supported sequential cross-metathesis/reduction.

An efficient and high-yielding "hydrogen-free" reduction of α,β-unsaturated alkenes was carried out employing Grubbs' catalyst in a non-metathetic role and Et(3)SiH. Conditions were optimized under microwave irradiation. Application to the solid-phase organic synthesis allows a facile construction of sp(3)-sp(3) carbon bonds through a sequential cross metathesis/olefin reduction.

Unravelling the olefin cross metathesis on solid support. Factors affecting the reaction outcome.

Olefin cross metathesis on solid support under a variety of conditions is described. A comprehensive analysis considering diverse factors governing the reaction outcome gives a series of patterns for the application of this useful methodology in organic synthesis. If the intrasite reaction is not possible, homodimerization of the soluble olefin is crucial.

Trapping and characterization of a reaction intermediate in carbapenem hydrolysis by B. cereus metallo-beta-lactamase.

Metallo-beta-lactamases hydrolyze most beta-lactam antibiotics. The lack of a successful inhibitor for them is related to the previous failure to characterize a reaction intermediate with a clinically useful substrate. Stopped-flow experiments together with rapid freeze-quench EPR and Raman spectroscopies were used to characterize the reaction of Co(II)-BcII with imipenem.

Solid-supported cross metathesis and the role of the homodimerization of the non-immobilized olefin.

We have prepared immobilized olefins as models for the cross metathesis using different olefin partners in the presence of second generation Grubbs and Hoveyda-Grubbs precatalysts. We have demonstrated that solid-phase cross metathesis is strongly dependent on the degree of homodimerization of the non-immobilized olefin and the reactivity of such a homodimer. As in the homogeneous phase, the Hoveyda-Grubbs precatalyst was better for immobilized alpha,beta-unsaturated carbonyl compounds.

A minimalistic approach to identify substrate binding features in B1 Metallo-beta-lactamases.

The 2-oxoazetidinylacetate sodium salt was synthesized as a model of a minimal beta-lactam drug. This compound and the monobactam aztreonam were assayed as substrates of the Metallo-beta-lactamase BcII. None of them was hydrolyzed by the enzyme.