Enantioselective Synthesis of α‑Heteroarylpyrrolidines by Copper-Catalyzed 1,3-Dipolar Cycloaddition of α‑Silylimines

α-Heteroarylpyrrolidines have
been efficiently prepared via
1,3-dipolar cycloaddition between silylimines and activated olefins.
In the presence of Cu­(CH3CN)4PF6/Walphos
as catalytic system, high levels of enantioselectivity (up to ≥99%
ee) and diastereoselectivity were achieved (major formation of C-2/C-4 trans-substituted pyrrolidines). The reaction is compatible
with a broad variety of dipolarophiles including maleimides, maleates,
fumarates, nitroalkenes, and vinylsulfones. The resulting cycloadducts
can be transformed into bioactive pyrrolidine derivatives.