Platinum-Catalyzed Cycloisomerization of 1,4-Enynes via 1,2-Alkenyl Rearrangement

The cycloisomerization of 1,4-enyne 1 in the presence of platinum(II) catalyst afforded 1,2,3-trisubstituted 1H-indene 2 and 2' in good to excellent yields. The reaction proceeded through an unprecedented 1,2-alkenyl rearrangement that afforded a novel reaction topology of 1,4-enynes.