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

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 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-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 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.