Fluoro-Aryl Substituted α,β2,3-Peptides in the Development of Foldameric Antiparallel β-Sheets: A Conformational Study

\u3b1,\u3b22,3 -Disteroisomeric foldamers of general formula Boc(S-Ala-\u3b2-2R,3R-Fpg)n OMe or Boc(S-Ala-\u3b2-2S,3S-Fpg)n OMe were prepared from both enantiomers of syn H-2-(2-F-Phe)-h-PheGly-OH (named \u3b2-Fpg) and S-alanine. Our peptides show two appealing features for biomedical applications: the presence of fluorine, attractive for non-covalent interactions, and aryl groups, crucial for \u3c0-stacking. A conformational study was performed, using IR, NMR and computational studies of diastereoisomeric tetra- and hexapeptides containing the \u3b22,3-amino acid in the R,R- and S,S-stereochemistry, respectively. We found that the stability of peptide conformation is dependent on the stereochemistry of the \u3b2-amino acid. Combining S-Ala with \u3b2-2R,3R-Fpg, a stable extended \u3b2-strand conformation was obtained. Furthermore, \u3b2-2R,3R-Fpg containing hexapeptide self-assembles to form antiparallel \u3b2-sheet structure stabilized by intermolecular H-bonds and \u3c0,\u3c0-interactions. These features make peptides containing the \u3b22,3-fluoro amino acid very appealing for the development of bioactive proteolytically stable foldameric \u3b2-sheets as modulators of protein-protein interaction (PPI)

Iodoamination of Alkenyl Sulfonamides by Potassium Iodide and Hydrogen Peroxide in Aqueous Medium

A procedure for the iodoamination of unfunctionalized olefins tethered to a tosyl-protected NH-group has been developed. The combined use of KI and H2O2 in aqueous medium was effective for the preparation of iodomethyl-substituted nitrogen-containing heterocycles. The selective exo-trig iodocyclization provided 1,2-bifunctional 5-, 6-, and 7-membered cyclic skeletons

Copper-Catalyzed/Hypervalent Iodine-Mediated Functionalization of Unactivated Compounds

The functionalization of unactivated substrates through the combination of copper catalysts and hypervalent iodine reagents represents a versatile tool in organic synthesis to access various classes of compounds. The hypervalent iodine derivatives can be used simply as oxidizing agents to regenerate the catalytic species or they can associate the functionalization of the starting material. In this review, special attention will be paid to methodologies which provide the introduction of nucleophiles into the reagent by use of suitable benziodoxol(on)es or iodonium salts. Many reactions concern C- and N-arylations, but may also involve formation of different carbon–carbon and carbon–nitrogen bonds, carbon–oxygen as well as carbon–halogen and carbon–phosphorus bonds

A new scaffold of topoisomerase I inhibitors: Design, synthesis and biological evaluation

The synthesis of a new hexacyclic system was realized starting from tryptamines and exploiting as a key step a sequential Pd-catalyzed N-arylation/acylation reaction. Having topoisomerases as biological target and the campthotecins class as benchmark, the new scaffold was decorated with substituents having different polarity and tested as Topoisomerase I inhibitors