Gold and TfOH‐Cocatalyzed Tandem Reaction of ortho‐Akynylarylaldehydes with Cyclopropenes: an Efficient Route to Functionalized Benzo[7]annulene Derivatives

A novel gold(III) and TfOH‐cocatalyzed reaction of ortho‐alkynylbenzaldehydes with cyclopropenes was described for the synthesis of a variety of functionalized benzo[7]annulene derivatives in a highly stereoselective manner. This reaction could undergo tandem [4+2] cycloaddition/ring expansion to achieve the construction of seven‐membered‐carbocycles, along with the cleavage of double bond of cyclopropenes. The reaction features simple operations, commercially available catalysts and broad substrate scope with good efficiencies.