Aromatic-Amide-Derived Nonbiaryl Atropisomer as Highly Efficient Ligand for Asymmetric Silver-Catalyzed [3 + 2] Cycloaddition

In
this work, we have successfully determined that the aromatic
amide-derived nonbiaryl atropisomer/silver complex (silver-Xing-Phos)
is an effective catalyst system for the solvent-dependent exo-selective cycloaddition of glycine aldimino esters with
chalcones or less-reactive methyl cinnamates to give the corresponding
chalcone- or cinnamate-derived pyrrolidines with multiple stereogenic
centers in good yields and high diastereoselectivities as well as
excellent enantioselectivities. Remarkably, it is the first example
of highly enantioselective silver-catalyzed [3 + 2] cycloaddition
of methyl cinnamates with glycine aldimino esters.