Fast Heck-Cassar-Sonogashira (HCS) Reactions in Green Solvents.

The replacement of toxic solvents with greener alternatives in Heck-Cassar-Sonogashira (HCS) cross-couplings was investigated. The fine-tuning of the HCS protocol allowed to achieve complete conversions and high speed under mild conditions. N-Hydroxyethylpyrrolidone (HEP) gave the best results. Moreover, the methodology was successfully applied to the synthesis of an intermediate of the anticancer drug Erlotinib, demonstrating the versatility of the new green protocol.

Fluorene benzothiadiazole co-oligomer based aqueous self-assembled nanoparticles.

Self-assembled π-conjugated nanoparticles with tunable optical characteristics are appealing for sensing and imaging applications due to their intrinsic fluorescence, supramolecular organization and dynamics. Here we report on the facile synthesis of fluorene benzothiadiazole co-oligomers in which structural backbone alterations induce bathochromically shifted optical characteristics. Moreover, the nature of the oligomer side-chains revealed the role of bulkiness and polarity on the optical and self-assembly behavior. Co-assemblies were prepared that showed energy transfer between the different oligomers which allows for tuning of the emission color. These compounds thus extend the π-conjugated-oligomer toolbox from which nanoparticles can be prepared with tailored physicochemical properties that may result in supramolecular materials for biosensing.

Molecular docking of opiates and opioid peptides, a tool for the design of selective agonists and antagonists, and for the investigation of atypical ligand-receptor interactions.

In the last years, molecular docking emerged as a powerful tool to investigate the interactions between opioid ligands and their receptors, thus driving the design and development of new selective agonists or antagonists of therapeutic interest. This review especially covers the most representative and recent comparative molecular docking analyses of structurally related compounds, as well as of agonists and antagonists within the active and inactive states of the receptors. The comparative analyses gave important information on the structural determinants responsible for the affinity and selectivity of the ligands, and defined the features responsible for the activation of the receptors. A special section is dedicated to the analyses of recently discovered, unusual agonists lacking of the tyramine pharmacophore, such as Salvinorin A, and the cyclopeptides which comprise the D-Trp-Phe pharmacophoric motif. For the atypical structure of these compounds, the docking proved to be essential to disclose how they interact with and activate the receptors.

Unusual amino acids: synthesis and introduction into naturally occurring peptides and biologically active analogues.

This review covers our recent advances in the synthesis of unusual amino acids in optically pure form, and their introduction into naturally occurring peptides with specific biological properties, or into modified bioactive peptides, aiming to obtain analogues displaying enhanced performances in term of activity, bioavailability and resistance to enzymatic hydrolysis.

NMR investigations on boron complexes in the conjugate addition on alpha,beta-unsaturated imides.

[reaction: see text]. The 1,4-addition of O-benzylhydroxylamine to alpha,beta-unsaturated imide 1 in the presence of BF3.Et2O proceeds with the preferential attack of the nucleophile on the Cbeta-re face. To explain this unexpected reactivity 1H, 13C, and 11B NMR investigations have been carried out on the boron-imide complex, which show the presence of an S-cis imide chain conformation.

A new selective synthesis of the Ile-allo-Thr-Gly tripeptide fragment of lysobactin.

[formula: see text] trans-Aziridine-2-carboxylic acid derivatives are useful intermediates for the synthesis of threonine or allo-threonine through ring expansion and SN2 displacement, respectively. We describe here the preparation of the Ile-allo-Thr-Gly 11 fragment of Lysobactin via the aziridine 9 intermediate.