Phosphomolybdic acid as a bifunctional catalyst for Friedel–Crafts type dehydrative coupling reaction

Phosphomolybdic acid (H 3 PMo 12 O 40 ) was found to be a bifunctional catalyst for C─C bond formation via the dehydrative reaction of diarylmethanols with various nucleophiles, including 2‐naphthols, indoles, benzofuran and benzothiophene. The protons in the catalyst might play a critical role in the activation of alcohol, while the polyanion was advantageous for stabilizing the carbocation species. The cooperative catalytic system showed its own merits, such as high reaction rate, low catalyst loading, mild conditions, excellent yields (up to 99%) and good functional group compatibility.