Beyond Tertiary Amines: Introducing Secondary Amines by Palladium/Norbornene‐Catalyzed Ortho Amination

Abstract

Since the discovery of the palladium/norbornene (Pd/NBE)‐catalyzed ortho amination in 2013, escaping the limitation of only yielding tertiary anilines has been a long‐standing challenge in the past decade. Here, we describe that, by carefully choosing the phosphine ligand and NBE mediator, installation of a N‐mono‐alkylamino group becomes feasible. The reaction tolerates a wide range of aryl iodide substrates and various N‐mono‐tertiary alkylamine‐derived electrophiles. Both ipso alkenylation and alkynylation can be realized. The synthetic utility of this method is exemplified in the formation of primary amino group via selective deprotection and streamlined access to N‐heterocycles. Preliminary success of installing a bulky N‐secondary alkylamino group and mechanistic understanding of the decomposition pathways of mono N‐alkylamine electrophiles have been obtained.