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.