A convenient method for the synthesis of 4,4-diarylbut-1-enes via the successive allylation of aromatic aldehydes and the Friedel–Crafts alkylation reaction of aromatic nucleophiles with the intermediary benzyl silyl ethers using HfCl4 or Cl2Si(OTf)2

The three-component coupling reaction among aromatic aldehydes, allyltrimethylsilane and aromatic nucleophiles is efficiently performed by the promotion of HfCl4. A similar reaction occurs using allyltributyltin as the first nucleophile to aromatic aldehydes with a catalytic amount of Cl2Si(OTf)2 generated in situ from SiCl4 and AgOTf.