Total synthesis of leopolic acid A, a natural 2,3-pyrrolidinedione with antimicrobial activity

The first total synthesis of leopolic acid A, a fungal metabolite with a rare 2,3-pyrrolidinedione nucleus linked to an ureido dipeptide, was designed and carried out. Crucial steps for the strategy include a Dieckmann cyclization to obtain the 2,3-pyrrolidinedione ring and a Wittig olefination to install the polymethylene chain. An oxazolidinone-containing leopolic acid A analogue was also synthesized. The antibacterial activity showed by both compounds suggests that they could be considered as promising candidates for future developments.

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

The effects on the redox properties of modifying the molecular skeleton of neutral bis-2-(4-dimethylamino)pyridinylidene electron donors, derived from 4-dimethylaminopyridine (4-DMAP), have been explored, by varying two parameters: (i) the length of a polymethylene chain linking the two pyridine-derived rings and (ii) the nature of the nitrogen substituents on the 4 and 4′ positions of the precursor pyridines. Restricting the bridge length to two methylene units significantly altered the redox profile, while changes in the nitrogen-substituents at the 4 and 4′ positions led to only slight changes in the redox potentials.