Cooperative Pd/Cu Catalysis to Spiro[indoline-2,3′-pyrrolidin]-2′-ones: Tandem Benzylation of α-Isocyano Lactams, Amine Addition, and N-Arylation

A tandem three-component reaction has been developed for the synthesis of spirocyclic 2-indolinylformamidines through a cooperative action of palladium and copper catalysts. The Pd-catalyzed benzylation of alpha-isocyano lactams with 2-bromobenzyl bromides allows efficient formation of alpha-substituted alpha-isocyano lactams. A subsequent in situ Cu-catalyzed amine addition to the isocyanide moiety provides amidine intermediates that readily undergo intramolecular N-arylation via the cooperative action of Pd/Cu catalysis, allowing a facile chiral resolution of the spirocyclic 2-indolines.