B(C6F5)3-Catalyzed 1,4-Allylation of Azadienes with Allyltrimethylsilanes

A metal-free 1,4-allylation of azadienes with allyltrimethylsilanes catalyzed by B(C₆F₅)₃ has been developed. The high Lewis acidity, good thermal stability, and good hydrolytic stability of the catalyst make this reaction efficient and operationally simple. In contrast to the previously reported 1,2-allylation of α,β-unsaturated imines, the 1,4-allylation of azadienes is described here for the first time. Benzofuran-, indene-, dihydronaphthalene-, chromene-, and benzothiophene-based allyl arylmethanes have been obtained in up to 95 % yield.