Stereoselective synthesis of functionalized pyrrolidines with all-carbon quaternary stereocenters is described. DYI3 catalyzed the ring opening of cyclopropanecarboxylate equivalents and promoted Mannich-type addition of the resulting alpha,alpha-disubstituted enolate intermediates to aryl and isomerizable alkyl imines, giving products in 86-58% yield and >96:4-84:16 diastereoselectivity.