Synthesis of Dihydroisoquinolone-Fused Cyclobutanes via Tandem Palladium-Mediated Olefin Migration and Photosensitized [2 + 2] Cycloaddition

A tandem palladium-mediated olefin migration and visible light-promoted [2 + 2] cycloaddition reaction was disclosed. It provides a facile method to synthesize the cyclobutane-fused dihydroisoquinolone-based polycycles bearing a methyl group. Further product derivatization enables the efficient construction of diverse cyclobutane derivatives. Mechanistic studies revealed that the palladium catalysts promoted the olefin migration and inhibited the direct [2 + 2] cyclization of substrates.