Remote Editing of Stacked Aromatic Assemblies for Heteroannular C−H Functionalization by a Palladium Switch between Aromatic Rings.

An approach allowing remote editing of stacked aromatic assemblies for heteroannular C−H functionalization would represent a transformative chemical toolbox that may make the diversification of complex molecules in a straightforward manner. However, such a C−H activation is usually less kinetically and thermodynamically favorable than homoannular ortho C−H activation and remains a fundamental challenge. Herein we disclose an engineer's approach, using a transient ligand as an interim bridge between two aryl rings (analogues to mountaintops) to anchor the metal center on the remote heteroannular C−H bond. As a proof‐of‐concept, we present the palladium‐catalyzed heteroannular C−H olefination of stacked aromatic assemblies with olefins and allylation with vinyl acetates using L‐tert‐leucine acid as a transient ligand. Mechanistic investigations suggest an unusual olefin coordination‐promoted interannular palladium migration process determinative for reversal of the site‐selectivity. [ABSTRACT FROM AUTHOR]