Visible Light‐Driven Copper‐Catalyzed Asymmetric Synthesis via Sequential C(sp ³ )─C(sp ³ ) Bond Scission

Abstract

ABSTRACT The selective and consecutive cleavage of C(sp 3 )─C(sp 3 ) bonds while simultaneously governing chemo‐, regio‐, and stereoselectivity constitutes a long‐standing unresolved challenge in synthetic chemistry. Here, we present a visible light‐driven copper catalysis platform that surmounts this obstacle. A chiral bisoxazoline copper complex acts as a multifunctional catalyst, and a tailored sodium sulfoxylate additive modulates the metal coordination sphere, altogether eliminating the requirement for an external photosensitizer. This streamlined system promotes twofold C(sp 3 )─C(sp 3 ) fragmentation of cyclobutanols and subsequent coupling with imines to construct quaternary carbon stereocenters, releasing ethylene as the sole byproduct. Integrated experimental and computational investigations delineate an unprecedented cascade mechanism: photoinduced ligand‐to‐metal charge transfer (LMCT) initiates strain‐release ring opening, a copper‐mediated β ‐cleavage executes the second fragmentation, and a highly enantioselective radical addition to the imine completes the stereodefined assembly. The sodium sulfoxylate additive proves indispensable for rerouting the pathway toward the second cleavage over premature radical trapping and elevating enantioselectivity to as high as 99% ee. By demonstrating rigorous kinetic command over multiple C(sp 3 )─C(sp 3 ) cleavages within a single cascade, this work establishes a new paradigm for photochemical asymmetric synthesis.