Hf(OTf)4-Catalyzed 1,6-Conjugate Addition of 2-Alkyl-azaarenes to para-Quinone Methides

Herein we reported a Hf(OTf)4-catalyzed carbon–carbon bond formation reaction between 2-alkyl-azaarenes and para-quinone methides (p-QMs). This 1,6-conjugate addition protocol offered rapid access to a large array of triarylethane products in good yields. The catalyst loading could be reduced to 1 mol %. Studies pertinent to scale-up reaction and product derivatization were also presented.