Palladium(II)-Catalyzed Remotemeta-C–H Functionalization of Aromatic Tertiary Amines

Abstract

Pd(II)-catalyzed remote C−H olefination of aromatic tertiary amines was achieved with high meta selectivity. With the assistance of an elaborated template, C−H functionalization of unreactive aryl tertiary amines, hindered by the p−π conjugation between the lone-pair electrons of the nitrogen atom and the phenyl ring, was realized with high meta regioselectivity via a quaternary ammonium salt assembly. The results demonstrate that apart from the distance and geometry of the template, the conformation of the arene substrate also plays a crucial role in the templated-assisted remote C−H functionalization.

Intramolecular Remote C–H Activation via Sequential 1,4-Palladium Migration To Access Fused Polycycles

“…In 2012, Yu and coworkers innovatively developed a U-shaped template that could well overcome the constraint of spatial geometry and accomplished the meta -C–H functionalization of arenes (Figure b) . Subsequently, Yu, − Tan, Maiti, Li, Jin, and Kong further established the versatility of this U-shaped template in the meta -C–H functionalization of arenes. In addition, Maiti and coworkers described a palladium-catalyzed remote para -C–H functionalization of arenes with a D-shaped biphenyl template-based assembly (Figure b) .…”

Palladium-Catalyzed Distal m-C–H Functionalization of Arylacetic Acid Derivatives

“…It was shown that selective m -C–H activation was attained by forming a macrocyclic cyclophane-like pretransition state . Subsequently, various research groups, including his group − and those of Maiti, − Tan, Li, , Jin, − and others, − have been active in m -C–H functionalization. Recently, our research group also disclosed the new and simple aliphatic nitrile group directing template 2-cyano-2-isobutyl-4-methylpentanoic acid synthesized from simple benchtop starting materials .…”

Synthesis of meta-Substituted Anilines via Copper-Catalyzed [1,3]-Methoxy Rearrangement

“…Accordingly, the development of a reaction system, namely, other than protocols involving electrophilic substitution reactions is highly desirable. Transition-metal-catalyzed direct meta -C–H functionalization reactions of anilines have been recently gathering much attention for this purpose (Scheme c), , realizing various functionalization reactions, such as arylation, borylation, alkylation, chlorination, and olefination, using well-designed ligands and directing groups. However, this state-of-the-art methodology still has some drawbacks, such as overfunctionalization due to equal reactivity between the two meta positions and low efficiency in the reactions of the para -substituted anilines presumably due to the steric repulsion between the neighboring para -substituent and the metal catalyst bound at the meta position in the arylmetal intermediate.…”