Palladium‐Catalyzed [2+2+1] Spiroannulation via Alkyne‐Directed Remote C−H Arylation and Subsequent Arene Dearomatization

Palladium‐catalyzed alkene‐directed cross‐coupling of aryl iodide with another aryl halide through C?H arylation opens a unique avenue for unsymmetrical biaryl‐derived molecules. However, homo‐coupling of aryl iodides often erodes the overall synthetic efficiency. Reported herein is a highly chemoselective Pd⁰‐catalyzed alkyne‐directed cross‐coupling of aryl iodides with bromophenols, which was subsequently followed by phenol dearomatization to furnish a very attractive 2+2+1] spiroannulation. Notably, possible homo‐coupling of aryl iodides was not observed at all. Mechanistic studies indicated that a five‐membered aryl/vinyl palladacycle most likely accounts for promoting the key step of biaryl cross‐coupling.