Binap and Phosphoramidites as Privileged Chiral Ligands for the Metal-Catalyzed Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Ylides

2,2'Bis(diphenylphosphino)-1,1'-binaphthyl (binap) and phosphoramidites are privileged chiral ligands that have been tested in the coinage-metal-catalyzed 1,3-dipolar cycloadditions of metalloazomethine ylides and electrophilic alkenes. Silver(I), copper(II), and gold(I) salts have been evaluated in all of these reactions. Maleimides, acrylates, fumarates, 1,2bis(phenylsulfonyl) ethylene, and enones reacted with imino esters to give the corresponding endoprolinates, such as hepatitis C (HCV) inhibitors, in high diastereo-and enantioselectivity using either binap-silver and -gold(I) or phosphoramidite-silver complexes. In the case of nitroalkenes, exo-4-nitroprolinates were obtained using silver or copper(II) phosphoramidite complexes. Azlactones reacted with maleimides and acrylates to give pyrrolines only in the presence of binapgold(I) complexes. The observed enantioselectivity and mechanism of these 1,3-dipolar cycloadditions were studied for the most relevant examples by means of DFT calculations.