Boron-Catalyzed Hydroarylation of 1,3-Dienes with Arylamines

Catalytic
hydroarylation reactions of conjugated dienes are achieved
using tris­(pentafluorophenyl)­borane as a Lewis acid catalyst under
mild reaction conditions. This new protocol shows a broad substrate
scope for the highly regioselective functionalization of sterically
hindered aniline derivatives. Experimental and extensive density functional
theory mechanistic studies show that the complex of residual water
and B­(C6F5)3 plays a crucial role
in the aryl-assisted protonation of conjugated dienes, forming allyl
cation intermediates that induce the facile electrophilic aromatic
substitution of aniline substrates.