Ni‐Catalyzed Cyclization of Enynes and Alkynylboronates: Atom‐Economical Synthesis of Boryl‐1,4‐dienes

We report a novel atom‐economical Ni‐catalyzed cyclization reaction of enynes with alkynylboronates. The reaction employs a non‐expensive Ni salt, a phosphine‐based ligand and easy‐handling alkynylboronates as boron–carbon source. The reaction provides complex fused‐bicyclic compounds containing borylated 1,4‐cyclohexadienes in high yields in short reaction times, involving the formation of two C−C bonds in one step. A reasonable reaction mechanism is proposed based on mechanistic experimental results.