Design of antimicrobially active small amphiphilic peptide dendrimers.

Novel polyfunctional small amphiphilic peptide dendrimers characterized by incorporation of a new core compounds - tris-amino acids or tetrakis-amino alcohols that originated from a series of basic amino acids - were efficiently synthesized. These new core elements yielded molecules with multiple branching and (+5)/(+6) charge at the 1-st dendrimer generation. Dendrimers exhibited significant antimicrobial potency against Gram(+) and Gram(-) strains involving also multiresistant reference strains (S.

Synthesis of pyrrolizidine alkaloids via 1,3-dipolar cycloaddition involving cyclic nitrones and unsaturated lactones.

The 1,3-dipolar cycloaddition of cyclic nitrone derived from tartaric acid and (S)-5-hydroxymethyl-2(5H)-furanone leads to a single adduct which was transformed into 2,6-dihydroxyhastanecine via reaction sequence involving reduction of the lactone moiety, glycolic cleavage of the terminal diol, and the N-O hydrogenolysis followed by the intramolecular alkylation of the nitrogen atom.

Synthesis of 1-homoaustraline.

The 1,3-dipolar cycloaddition of a five-membered cyclic nitrone derived from malic acid and unsaturated D-threo-hexonolactone leads to a single adduct, which was transformed into 1-homoaustraline via a reaction sequence involving rearrangement of the six-membered lactone ring into the five-membered one, removal of the terminal carbon atom from the sugar chain, reduction of the lactone fragment into triol, protection of primary hydroxy groups, mesylation of the secondary one, cleavage of the N-O bond, and the intramolecular alkylation of the nitrogen atom.