Tungsten(0)‐ and rhenium(I)‐catalyzed reactions of acetylenic dienolsilylethers based on the concept of geminal carbo‐functionalization of alkynes are reported. Treatment of 3‐siloxy‐1,3‐diene‐7‐ynes with catalytic amounts of [W(CO)6] or [ReCl(CO)5] under photoirradiation conditions gives synthetically useful bicyclo[3.3.0]octane derivatives in good yields. Extremely high catalytic activity is noted
Tandem bicycle: A gold‐catalyzed geminal carbo‐functionalization reaction of 3‐siloxy‐1,3‐dien‐8‐ynes proceeded smoothly to give bicyclo[4.3.0]nonanes stereoselectively through ring expansion of the bicyclic carbene complex intermediates. The product configuration was different from that of the thermal Diels–Alder adduct.