Reductive Cycloisomerization of Diynes by Supported Palladium Catalysts and Subsequent [4+2] Cycloaddition for One‐Pot Synthesis of Cyclohexenes

: Supported Pd nanoparticles catalyzed the reductive cycloisomerization of diynes to give 1,3‐dienes, and subsequent intermolecular [4+2] cycloaddition with dienophiles led to cyclohexene derivatives. Various diynes and dienophiles participated in the one‐pot reaction to give the corresponding products in good to high yields. Al2O3‐supported Pd catalysts were highly tolerant toward air and reusable. One‐pot synthesis of cyclohexene derivatives was achieved via supported Pd nanoparticles catalyzed the reductive cycloisomerization of diynes to give 1,3‐dienes, and subsequent intermolecular [4+2] cycloaddition with dienophiles. Various diynes and dienophiles participated in the present catalytic reaction. Al2O3‐supported Pd catalysts were highly tolerant toward air and reusable.