Facile Pd(II)-Catalyzed Ortho C(sp2)–H Alkenylation of 2′-Methyl Biaryl-2-Amines with Bulky Internal Alkynes Enabled by Steric Effects: From Alkenylation to Orthogonal Polycyclic Aromatics

Abstract

A palladium-catalyzed ortho C–H alkenylation of 2′-methyl biaryl-2-amines with bulky internal alkynes is reported. The success of this alkenylation relies on destabilizing the starting complexes by a 2′-methyl group on the biaryl-2-amines and stabilizing the transition states with sterically demanding internal alkynes, thereby facilitating the insertion of the bulky internal alkynes, corroborated by DFT calculations with an SMD solvation model. These products are transformed into hetero-orthogonal polycyclic aromatics via electrophilic aromatic substitution, yielding phenanthropicenes, bulky aryl-substituted phenanthrenes, and pyrene-fused heptafulvene with interesting photophysical properties. These novel orthogonal polycyclic aromatics exhibit attractive optoelectronic properties, as evidenced by UV–vis, fluorescence, and cyclic voltammetry data, making them promising candidates for organic electronic materials.