The [2 + 2] cycloaddition reaction constitutes a powerful tool for the construction of cyclobutane-fused scaffolds. A protocol for the intermolecular cycloaddition of 1-acetylindoles was developed where [Au(SIPr)Cbz] has proven indispensable for this purpose, while conventional photocatalysts, such as iridium and organic photosensitizers, have shown limited efficiency. Our findings unlocked the synthesis of cyclobutane-fused indolines, without any required substituent at the C2 or C3 position.