Unexpected Grob-type fragmentation of vinylogous β-silyloxy-cyclobutanone into γ-lactone

An unusual formal oxy transposition of vinylogous β-silyloxy-cyclobutanone 1 under mild acidic conditions to the decalinic γ-lactone 2 was described. A plausible mechanistic pathway involving the Grob-type fragmentation and intramolecular γ-lactonization was proposed.