Radical Annulation for the Synthesis of Cyclopenta[c]chromene Derivatives

Abstract A Cu‐catalyzed oxidative radical [2+2+1] annulation reaction of phenol‐linked 1,7‐enynes with α ‐active methylene nitrile is described, affording cyclopenta[ c ]chromene derivatives bearing several functional groups in excellent yields. The wide substrate range, good group tolerance, and easy amplification experiments indicate the practicability of this synthesis strategy. This process provides an alternative convenient route for the synthesis of cyclopenta[ c ]chromene derivatives.