Regio- and Stereoselective Allylation of Anilines with Aryl Allenes in Hexafluoroisopropanol Solvent

A regio- and stereoselective allylation of N-unsubstituted anilines has been developed that explores aryl allenes as masked allyl synthons and a combination of Mg(OTf)2/HFIP as an effective proton source. The protocol is operationally simple and scalable and offers high yields of diverse p-allyl anilines bearing an olefin motif with exclusive E-geometry. The methodology was also suitable for the regioselective allylation of indole and can be advanced in a three-component reaction mode using NIS activator. The alteration of the catalytic system with TfOH resulted in the regioselective difunctionalization of allenes, which follows an allylation/hydroarylation cascade.