Substrate NOBINAc ligand affinity for Pd^II-catalyzed enantioselective C-H activation over reactive β-C-H bonds in...

Ferrocenyl amines as directing groups for C-H activation have limitations as they are prone to undergo oxidation, allylic deamination, and β-hydride elimination. The fundamental challenge observed here is the competition between the desired C-H activation versus the vulnerable β-C-H bond activation of amines and fine-tuning of a suitable oxidant which avoids the oxidation of the β-C-H bond and ferrocene. Herein, the potential of an axially chiral NOBINAc ligand is revealed to implement the enantioselective Pd^II-catalyzed C-H activation process of ferrocenyl amines. Mechanistically, the affinity between the NOBINAc ligand and sulfonate group of amine facilitated by the Cs⁺ cation plays an impressive role in the desired reaction outcome via an enhanced substrate ligand affinity. This approach resulted in a Pd-catalyzed enantioselective C-H activation, the first intermolecular annulation, and alkenylation of ferrocenyl amines with allenes and olefins, leading to ferrocene fused tetrahydropyridines and alkenylated ferrocenyl amines with up to 70% yields and 99 : 1 er.