Palladium-Catalyzed Ring-Closing Aminoalkylative Amination of Unactivated Aminoenynes

An efficient strategy for preventing the beta-hydride elimination of alkylpalladium species by ligation of the palladium with adjacent amino-group was developed, which enabled a novel palladium-catalyzed ring-closing aminoalkylative amination of unactivated aminoenynes. The reaction is amenable to aminals, as well as aliphatic aldehydes with secondary amines, which provides straightforward access to structurally diverse exocyclic allenic amines bearing 5 to 12-membered N-heterocycles. With chiral phosphoramidite-ligated palladium complex as the catalyst, an enantioselective variant was achieved with up to 93 % ee. Simultaneously, synthetic transformations of the chiral products were also conducted to afford structurally unique spirodiamines including one pharmaceutically active molecule via axial-to-central chirality transfer.

Automated summary

An efficient strategy for preventing beta-hydride elimination of alkylpalladium species by ligating palladium with adjacent amino group was developed, enabling a novel palladium-catalyzed ring-closing aminoalkylative amination of unactivated aminoenynes. The reaction is applicable to aminals and aliphatic aldehydes with secondary amines, providing straightforward access to structurally diverse exocyclic allenic amines with 5 to 12-membered N-heterocycles. A chiral phosphoramidite-ligated palladium complex was used as the catalyst to achieve an enantioselective variant with up to 93% ee. Synthetic transformations of the chiral products also resulted in structurally unique spirodiamines, including one pharmaceutically active molecule, through axial-to-central chirality transfer.