Enantioselective synthesis of proline derivatives by 1,3-dipolar cycloadditions

Research devoted to the synthesis of highly substituted prolines, which are hepatitis C virus inhibitors, using 1,3-dipolar cycloadditions (1,3-DC) of azomethine ylides is described. In the first part, a diastereoselective approach using an inexpensive lactate-derived acrylate as dipolarophile is described. In the second part, our efforts using simple and easily accessible chiral silver(I) and gold(I) complexes as catalysts for enantioselective synthesis of proline derivatives are reviewed. In this case, chiral phosphoramidites and binap have been used as privileged ligands. Parallel to these experimental results, considerable effort was dedicated to run semiempirical density functional theory (DFT) calculations to explain and justify the stereoselectivity of each process.This work has been supported by the DGES of the Spanish Ministerio de Ciencia e Innovación (MICINN) (Consolider INGENIO 2010 CSD2007-00006, FEDER-CTQ2007-62771/BQU, and by the Hispano-Brazilian project PHB2008-0037-PC), Generalitat Valenciana (PROMETEO/2009/039), and by the University of Alicante (GITE-09020-UA)